- a. Notification of tests. When specified (see Annex B, paragraph 2b), notification of Type I or Type II testing shall be made in accordance with DI-MISC-81624 (see Annex B, paragraph 3).
- b. Identification of component compliance. When specified (see Annex B, paragraph 2c), the information verifying that the component complies with Type I and Type II testing shall be identified on the component drawing, the Test Report (DI-ENVR-81647) (see Annex B, paragraph 3), or an identification plate attached to the component.
- c. Disposition of tested equipment. The requirements for tested equipment, fixturing, associated test records, and other documentation shall be as specified (see Annex B, paragraph 2d).
528.1-4 TAILORING GUIDANCE FOR CONTRACTUAL APPLICATION
Note: Equipment installed aboard Naval ships is subjected to varying frequencies and amplitudes of environmental vibration for extended periods of time, during which they are required to perform their normal function. Principal causes of steady state shipboard vibration are propeller blade excitation and unbalanced forces of the propeller and shafting. Vibrations are also experienced by shipboard mounted equipment caused by mounting system resonances, changes in ship speed and heading, and changes in sea state. Vibration magnitudes measured on a ship during vibration trials should not be compared with the magnitudes shown in Table 528.1-I because ship vibration trials are conducted in quiet water to achieve repeatable results during which changes in speed and heading are not made. See ANSI S2.25 for additional tailoring guidance.
- a. The frequency range for Type I vibrations is determined based on blade rate frequencies associated with a specific ship design. If equipment is to be tested for use on multiple ship classes, the equipment may be tested over the frequency range encompassing various ship classes as required.
- b. For Type I testing, if equipment is to be tested for use on multiple ship classes, the choice of equipment mounting may affect the number of tests required to qualify the equipment for use on the intended ships.
528.1-4 ENVIRONMENT ELEMENTS – Climatic Design Types – Natural and Induced.PART THREE-10
| 4.1 | Hot climatic design types | PART THREE-10 |
| 4.1.1 | High temperature | PART THREE-11 |
| 4.1.1.1 | Hot-dry cycle (A1) | PART THREE-11 |
| 4.1.1.2 | High temperature with low relative humidity | PART THREE-12 |
| 4.1.2 | High temperature with high humidity | PART THREE-14 |
| 4.1.3 | High absolute humidity | PART THREE-15 |
| 4.1.3.1 | Hot-humid cycle (B3) | PART THREE-15 |
| 4.2 | Basic climatic design type | PART THREE-16 |
| 4.2.1 | High relative humidity with high temperature | PART THREE-16 |
| 4.2.2 | High humidity daily cycles | PART THREE-17 |
| 4.2.3 | Temperature, humidity, solar radiation (constant high humidity cycle (B1)) | PART THREE-18 |
| 4.2.4 | Temperature, humidity, solar radiation (variable high humidity cycle (B2)) | PART THREE-18 |
| 4.2.5 | Basic hot daily cycle (A2) | PART THREE-19 |
| 4.2.6 | Basic cold daily cycle (C1) | PART THREE-20 |
| 4.3 | Cold and severe cold design types | PART THREE-21 |
| 4.3.1 | Low temperature | PART THREE-21 |
| 4.3.2 | Cold climate design type (C2) | PART THREE-23 |
| 4.3.3 | Severe cold climatic design type (C3) | PART THREE-24 |
| 4.3.4 | High relative humidity with low temperature | PART THREE-24 |
| 4.3.5 | Low relative humidity with low temperature | PART THREE-24 |
| 4.3.6 | Low absolute humidity | PART THREE-24 |
MIL-STD-810H
PART THREE
CONTENTS - Continued
| Paragraph | Page | |
|---|---|---|
| 5. | ADDITIONAL ENVIRONMENTAL ELEMENTS | PART THREE-25 |
| 5.1 | Wind | PART THREE-25 |
| 5.1.1 | Wind element | PART THREE-25 |
| 5.1.2 | Wind speed. | PART THREE-25 |
| 5.2 | Rain | PART THREE-27 |
| 5.2.1 | Intensities | PART THREE-27 |
| 5.2.2 | Rainfall rate. | PART THREE-28 |
| 5.3 | Snow | PART THREE-29 |
| 5.4 | Ice | PART THREE-32 |
| 5.4.1 | Ice phenomena | PART THREE-32 |
| 5.4.2 | Ice accretion. | PART THREE-33 |
| 5.5 | Atmospheric pressure. | PART THREE-33 |
| 5.6 | Ozone concentration. | PART THREE-33 |
| 5.7 | Sand and dust | PART THREE-33 |
| 5.8 | Dust as a natural obscurant. | PART THREE-34 |
| 5.9 | Freeze-thaw cycles. | PART THREE-36 |
| 5.9.1 | Basic cold-wet cycle | PART THREE-36 |
| 5.10 | Microbial growth (fungus/mould). | PART THREE-37 |
| 5.11 | Hail | PART THREE-38 |
| 5.12 | Combined environmental effects | PART THREE-38 |
| 5.13 | High elevations and upper air conditions. | PART THREE-39 |
| 6. | REFERENCED/RELATED DOCUMENTS | PART THREE-39 |
| 6.1 | Reference documents | PART THREE-39 |
| 6.2 | Related documents | PART THREE-39 |
FIGURES
| Figure 1. | Areas of occurrence of climatic design types | PART THREE-5 |
| Figure 2. | Distribution of absolute minimum temperatures | PART THREE-6 |
| Figure 3. | Distribution of absolute maximum temperatures | PART THREE-7 |
TABLES
| Table I. | Summary of climatic conditions and daily cycles of temperature, solar radiation, and RH | PART THREE-10 |
| Table II. | Hot climatic design type A1: Hot-dry daily cycle (Natural and Induced) | PART THREE-13 |
| Table III. | Daily cycle of temperature & other elements associated with worldwide long-term extremes of high temperature | PART THREE-14 |
| Table IV. | Abadan frequencies of occurrence of high temperatures with high humidity | PART THREE-15 |
| Table V. | Hot climate design type B3: Hot-humid daily cycle | PART THREE-16 |
| Table VI. | Basic climatic design type B1: Constant high humidity daily cycle | PART THREE-18 |
| Table VII. | Basic climatic design type B2: Variable high humidity daily cycle. | PART THREE-19 |
| Table VIII. | Basic climatic design type A2: Basic hot daily cycle. | PART THREE-20 |
| Table IX. | Basic climatic design type C1: Cold daily cycle | PART THREE-21 |
MIL-STD-810H
PART THREE
CONTENTS - Continued
| Paragraph | Page | |
|---|---|---|
| Table X. | Monthly cycle of temperature associated with the worldwide long term low temperature extremes | PART THREE-22 |
| Table XI. | Cold climate design type C2: Daily cycle | PART THREE-23 |
| Table XII. | Wind speed multiplication factors at selected heights | PART THREE-25 |
| Table XIII. | Associated gusts (m/s) | PART THREE-26 |
| Table XIV. | Associated gusts, m/s (mph) | PART THREE-27 |
| Table XV. | Rainfall intensities - Drop diameter range | PART THREE-27 |
| Table XVI. | Raindrop concentrations per cubic meter | PART THREE-29 |
| Table XVII. | Long term extreme rainfall rates (cm/h) | PART THREE-29 |
| Table XVIII. | Horizontal mass fluxes for blowing snow | PART THREE-30 |
| Table XIX. | Typical distribution of blowing snow particle sizes | PART THREE-30 |
| Table XX. | Highest recorded snow mass fluxes | PART THREE-32 |
| Table XXI. | Number of days per year with dust storms (visibility <1 km)................ | PART THREE-35 |
| Table XXII. | Cold-wet daily cycle of temperature, humidity, and solar radiation | PART THREE-37 |
| Table XXIII. | European test fungus species | PART THREE-38 |
| Table XXIV. | Low air pressure and temperature at elevation | PART THREE-39 |
PART THREE ANNEX A. WEATHER AND CLIMATIC EXTREMES – A BRIEF SUMMARY
| 1. | INTRODUCTION | PART THREE-A-1 | |
| 2. | MIL-HDBK-310 | PART THREE-A-1 |
ANNEX A FIGURES
| Figure A-1. Temperature extremes | PART THREE-A-3 |
| Figure A-2. Precipitation extremes | PART THREE-A-6 |
| Figure A-3. Miscellaneous extremes | PART THREE-A-8 |
A TABLES
| Table A-I. Weather Conditions & Climatic Extremes - Brief Summary. | PART THREE-A-1 |
| Table A-II. Precipitation extremes. | PART THREE-A-4 |
| Table A-III. Miscellaneous extremes | PART THREE-A-7 |
PART THREE ANNEX B. TERMINOLOGY
| 1. | TERMS | PART THREE-B-1 |
|---|---|---|
| 1.1 | Climatic design types. | PART THREE-B-1 |
| 1.2 | Daily weather cycles. | PART THREE-B-1 |
| 1.3 | Operational, and storage and transit conditions | PART THREE-B-1 |
PART THREE ANNEX C. COMPARISON OF AR 70-38 WITH MIL-HDBK-310
| 1. | RELATIONSHIP BETWEEN AR 70-38 AND MIL-HDBK-310 | PART THREE-C-1 |
|---|---|---|
| 1.1 | Background | PART THREE-C-1 |
| 1.2 | Risk policy | PART THREE-C-2 |
| 1.3 | Additional guidance | PART THREE-C-2 |
Downloaded from https://www.everyspec.com
MIL-STD-810H PART THREE
(This page is intentionally blank.)
This Part has been extracted in whole or in part from Army Regulation (AR) 70-38, “Research, Development, Test and Evaluation of Materiel for Extreme Climatic Conditions,” from the Environmental Standards for Materiel Design Group of the AirLand Battlefield Environment Executive (ALBE) Committee (1987), “Environmental Factors and Standards for Atmospheric Obscurants, Climate, and Terrain,” Washington, D.C., and MIL-HDBK-310, “Global Climatic Data for Developing Military Products,” and modified to fit the format of this document. Although originally prepared for Army and DoD applications, the included data (unless otherwise noted), coincide with NATO STANAG 4370, AECTP 230.
PART THREE – WORLD CLIMATIC REGIONS – GUIDANCE SECTION I - INTRODUCTION
528.1-4 ENVIRONMENT ELEMENTS - Climatic Design Types - Natural and Induced
Table I provides a comprehensive summary of the commonly accepted natural environment climatic design types, as well as published induced (storage and transit) conditions. Note that when considering the "Storage and Transit" values, the values shown are cyclic, and use of the "Daily High" values may be an overtest based on the LCEP.
TABLE I. Summary of climatic conditions and daily cycles of temperature, solar radiation, and RH
| Climatic Design Type | Daily Cycle¹ | Operational Conditions | Storage and Transit Conditions | |||||
|---|---|---|---|---|---|---|---|---|
| Ambient Air Temperature² °C (°F) | Solar Radiation W/m² (Bph³) | Ambient Relative Humidity (Percent RH&sup4;) | Induced Air Temperature °C (°F) | Induced Relative Humidity (Percent RH) | ||||
| Daily Low | Daily High | Daily Low | Daily High | |||||
| Hot | Hot Dry (A1) | 32 (90) | 49 (120) | 0 to 1120 (0 to 355) | 8 to 3 | 33 (91) | 71 (160) | 7 to 1 |
| Hot Humid (B3) | 31 (88) | 41 (105) | 0 to 1080 (0 to 343) | 88 to 59 | 33 (91) | 71 (160) | 80 to 14 | |
| Basic | Constant High Humidity (B1) | Nearly Constant 24 (75) | Negligible | 95 to 100 | Nearly Constant 27 (80) | 95 to 100 | ||
| Variable High Humidity (B2) | 26 (78) | 35 (95) | 0 to 970 (0 to 307) | 100 to 74 | 30 (86) | 63 (145) | 75 to 19 | |
| Basic Hot (A2) | 30 (86) | 43 (110) | 0 to 1120 (0 to 355) | 44 to 14 | 30 (86) | 63 (145) | 44 to 5 | |
| Intermediate&sup6; (A3) | 28 (82) | 39 (102) | 0 to 1020 (0 to 323) | 78 to 43 | 28 (82) | 58 (136) | See note 5 | |
| Basic Cold (C1) | -32 (-25) | -21 (-5) | Negligible | Tending toward saturation | -33 (-28) | -25 (-13) | Tending toward saturation | |
| Cold | Cold (C2) | -46 (-50) | -37 (-35) | Negligible | Tending toward saturation | -46 (-50) | -37 (-35) | Tending toward saturation |
| Severe Cold | Severe Cold (C3) | -51 (-60) | Negligible | Tending toward saturation | -51 (-60) | Tending toward saturation | ||
- Designations in parentheses refer to corresponding climatic categories in MIL-HDBK-310 and AR-70-38 (except the A-3 category) and NATO STANAG 4370, AECTP 200, AECTP 230, (see Part One, paragraphs 2.2.1, 2.2.2, and 2.3).
- ² °C values (rounded to the nearest whole degree) derived from data obtained/established on °F scale.
- ³ Bph represents British Thermal Units per square foot per hour.
- 4 Sequence of RH presentation corresponds to sequence of air temperatures shown (e.g., for HOT-DRY daily cycle, 8 percent RH occurs at 32°C (90°F); 3 percent RH occurs at 49°C (120°F).
- 5 Relative humidity for the A3 storage condition vary to widely between different situations to be represented by a single set of conditions.
- 6 Values are only found in NATO STANAG 4370, AECTP 230.
NOTE: The numbers shown for the values of the climatic elements represent only the upper and lower limits of the cycles that typify days during which the extremes occur, e.g., for the Hot-Dry cycle, 49°C (120°F) is the maximum daytime temperature, and 32°C (90°F) is the minimum nighttime (or early morning) temperature.
4.1 Test Facility
Use a test facility, including all auxiliary equipment, capable of providing the specified vibration environments and the control strategies and tolerances discussed in paragraph 4.2. In addition, use measurement transducers, data recording and data reduction equipment capable of measuring, recording, analyzing, and displaying data sufficient to document the test and to acquire any additional data required. Unless otherwise specified, perform the specified vibration tests, and take measurements at standard ambient conditions as specified in Part One, paragraph 5.1.
528.1-4.1 Hot climatic design type
Two daily cycles represent conditions that occur within the hot climatic design type areas. Of these the hot-dry is much more extensive than the hot-humid.
MIL-STD-810H
PART THREE
4.1.1 High temperature. (Paragraph 6.1, reference a, paragraph 5.1.1.)
Temperatures presented were observed in standard meteorological instrument shelters. They represent temperatures of free air in the shade about 1.5m above the ground. These temperatures will normally be encountered only during strong sunshine and fairly light winds. Ground surface temperatures will attain temperatures 15 to 30°C (59 to 86°F) higher than that of free air, depending on radiation, conduction, wind, and turbulence. Air layers very close to the surface will be only slightly cooler than the ground, but the decrease with height above the surface is exponential, so temperatures at 1m will be only slightly warmer than those observed in the instrument shelter.
The temperature of materiel exposed to high temperatures will vary greatly with the physical properties of the materiel affecting heat transfer and capacity, and with the type of exposure. The heat load from a realistic diurnal air temperature and solar radiation cycle make up only a part of the heat transferred to the materiel. The materiel temperature will also be dependent on solar radiation reflected to it from the ground, long wave radiation from the heated ground, long wave radiation to the cold sky, scattered solar radiation from the sky and nearby clouds, the vertical temperature distribution in the free air surrounding the materiel, and total ventilation from wind and turbulence.
- a. Highest Recorded. The world’s highest recorded surface temperature, 56.7 °C (134 °F), was measured on 10 July 1913 at Greenland Ranch (Death Valley), California, USA.
- b. Frequency of Occurrence. Because of insufficient hourly data to determine the distribution of high temperature versus frequency of occurrence on a global basis, a statistical technique was used to estimate percentile temperatures for thousands of locations worldwide. The high temperature analyses were used to determine the areas of the world with the highest 1-, 5-, and 10-percent temperatures during the worst month.
The hottest area of the world lies in the interior of northern Africa eastward to India. The hottest part of this area is the Sahara desert that qualifies as the worst part of the world for high temperature. The 1-, 5-, and 10-percent temperatures are 49°C (120°), 46°C (115°F), and 45°C (113°F), respectively.
Hot extremes are part of a well pronounced diurnal cycle. The daily maximum lasts only a couple of hours. However, it is accompanied by intense solar radiation that causes materiel to attain temperatures considerably higher than free air values. Therefore, a realistic diurnal cycle should be considered with the hot extreme. The cycle should also include wind speed that serves as a limiting factor to heat intensification. The moisture content should also be considered because the extremely low relative humidities that can be present during the hottest situations, may present special design problems.
If designing for the 1-percent temperature any place in the world during the warmest month of the year, use the diurnal cycle in which the air temperature attains a maximum of at least 49°C (120°F) at a height of about 1.5m above the ground. Table II describes the A1 climatic category to include the associated solar radiation, relative humidity, and wind speed. Diurnal cycles associated with the 5- and 10-percent temperatures can be approximated by subtracting 3°C and 4C (5°Fand 9°F) and, respectively, from each of the hourly temperatures in Table II. Values for the other elements in the cycle would not vary significantly from those associated with the 1-percent value because lower temperatures could be caused by other meteorological conditions.
- c. Long-term extremes. Long term high temperature extremes that would be expected to occur at least once during 10, 30, and 60 years in the hottest part of the world are 53°C (128°F), 54°C (130°F), and 55°C (131°F), respectively (see Table III). These values were derived from statistical analysis of 57 years of temperature data from Death Valley, California, and are considered representative of conditions in the Sahara desert. Table III includes diurnal cycles, associated solar radiation, relative humidity, and wind speeds.
Temperatures presented were observed in standard meteorological instrument shelters. They represent temperatures of free air at about 1.5m (4.9 ft) above the ground surface. Temperatures within a few cm of the surface could be 4 to 5°C (8°Fand 9°F) colder. Typically this is not referred to as a climatic design type. However, the LCEP may delineate the need for these values.
4.1.1.1 Hot-dry cycle (A1)
-
a. Location. Hot-dry conditions are found seasonally in the deserts of northern Africa, the Middle East, Pakistan, and India, southwestern United States, north central Australia, and northern Mexico (Figure 1).
-
b. Temperature, humidity, solar radiation.
-
(1) Operational conditions. On the extreme hot-dry days, temperature, humidity, and solar radiation may follow a pattern similar to that shown in Table II. Nominal accompanying wind speeds at the time of high temperatures are 4 mps (13 fps). The maximum ground surface temperature is 63°C (145°F). At ground elevations above 915m (3,000 feet), maximum air temperatures will be lower by approximately 9.1°C per 1,000m (5°F per 1,000 ft.), and solar radiation may be higher by approximately 43 W/m² per 1,000m (4 BTU/ft²/hr (British thermal units per square foot per hour)) per 1,000 feet, to 4572m (15,000 feet).
-
(2) Storage and transit conditions. The daily cycle for storage and transit in Table II shows 5 continuous hours with air temperatures above 66°C (150°F), and an extreme air temperature of 71°C (160°F) for not more than 1 hour. Testing for these conditions should be done, if practical, according to the daily cycle because prolonged exposure to the high temperature extremes may impose an unrealistic heat load on materiel. If not practical, testing will be done at a temperature representative of the peak temperature that the materiel would attain during a daily cycle.
4.1.1.2 High Temperature with low relative humidity
The lowest relative humidities approach zero percent in hot deserts distant from bodies of water.
- a. Lowest Recorded. The lowest recorded relative humidity of 2 percent at 43.3°C (110°F) was recorded in Death Valley, California.
- b. Frequency of Occurrence. Since the percentile values of low relative humidity vary very little, the RH cycle (A1) shown in Table II is recommended.
- c. Long-term Extremes. The recommended low relative-humidity cycle associated with the long-term high temperature extremes can be found in Table III.
Table II. Hot climatic design type A1: Hot-dry daily cycle (Natural and Induced).
| Local Time | OPERATIONAL CONDITIONS (Natural Environment) | STORAGE AND TRANSIT CONDITIONS | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Ambient Air Temp. | Solar Radiation | Relative Humidity | Dewpoint Temp. | Wind (at 3m) | Induced Air Temp. | Relative Humidity | |||
| (LST) | °C (°F) | Bph | W/m² | Percent | °C (°F) | m/s | ft/sec | °C (°F) | Percent |
| 0100 | 35 (95) | 0 | 0 | 6 | -7 (19) | 3 | 9 | 35 (95) | 6 |
| 0200 | 34 (94) | 0 | 0 | 7 | -6 (21) | 3 | 9 | 34 (94) | 7 |
| 0300 | 34 (93) | 0 | 0 | 7 | -7 (20) | 3 | 9 | 34 (93) | 7 |
| 0400 | 33 (92) | 0 | 0 | 8 | -6 (22) | 3 | 9 | 33 (92) | 7 |
| 0500 | 33 (91) | 0 | 0 | 8 | -6 (22) | 3 | 9 | 33 (92) | 7 |
| 0600 | 32 (90) | 18 | 55 | 8 | -6 (22) | 3 | 9 | 33 (91) | 7 |
| 0700 | 33 (91) | 85 | 270 | 8 | -6 (22) | 3 | 9 | 36 (97) | 5 |
| 0800 | 35 (95) | 160 | 505 | 6 | -7 (19) | 3 | 9 | 40 (104) | 4 |
| 0900 | 38 (101) | 231 | 730 | 6 | -5 (23) | 3 | 9 | 44 (11) | 4 |
| 1000 | 41 (106) | 291 | 915 | 5 | -4 (24) | 4 | 14 | 51 (124) | 3 |
| 1100 | 43 (110) | 330 | 1040 | 4 | -6 (21) | 4 | 14 | 56 (133) | 2 |
| 1200 | 44 (112) | 355 | 1120 | 4 | -5 (23) | 4 | 14 | 63 (145) | 2 |
| 1300 | 47 (116) | 355 | 1120 | 3 | -8 (18) | 4 | 14 | 69 (156) | 1 |
| 1400 | 48 (118) | 330 | 1040 | 3 | -9 (16) | 4 | 14 | 70 (158) | 1 |
| 1500 | 48 (119) | 291 | 915 | 3 | -8 (18) | 4 | 14 | 71 (160) | 1 |
| 1600 | 49 (120) | 231 | 730 | 3 | -7 (19) | 4 | 14 | 70 (158) | 1 |
| 1700 | 48 (119) | 160 | 505 | 3 | -8 (18) | 4 | 14 | 67 (153) | 1 |
| 1800 | 48 (118) | 85 | 270 | 3 | -9 (16) | 4 | 14 | 63 (145) | 2 |
| 1900 | 46 (114) | 18 | 55 | 3 | -7 (19) | 4 | 14 | 55 (131) | 2 |
| 2000 | 42 (108) | 0 | 0 | 4 | -7 (20) | 4 | 14 | 48 (118) | 3 |
| 2100 | 41 (105) | 0 | 0 | 5 | -6 (22) | 4 | 14 | 41 (105) | 5 |
| 2200 | 39 (102) | 0 | 0 | 6 | -4 (24) | 4 | 14 | 39 (103) | 6 |
| 2300 | 38 (100) | 0 | 0 | 6 | -6 (22) | 4 | 14 | 37 (99) | 6 |
| 2400 | 37 (98) | 0 | 0 | 6 | -7 (20) | 3 | 9 | 35 (95) | 6 |
Table III. Daily cycle of temperature & other elements associated with worldwide long-term extremes of high temperature. (See paragraph 4.1.1c.)
| Local Time | Temperature °C (°F) | RH | Wind (at 3m (10 ft)) | Solar Radiation | ||||
|---|---|---|---|---|---|---|---|---|
| Period (yrs) | (Percent) | m/s | (ft/s) | (W/m²) | (Bph) | |||
| (LST) | 10 | 30 | 60 | |||||
| 0100 | 36(97) | 36(97) | 36(97) | 6 | 3 | 9 | 0 | 0 |
| 0200 | 36(96) | 36(96) | 36(96) | 7 | 3 | 9 | 0 | 0 |
| 0300 | 36(96) | 36(96) | 36(96) | 7 | 3 | 9 | 0 | 0 |
| 0400 | 34(94) | 34(94) | 34(94) | 8 | 3 | 9 | 0 | 0 |
| 0500 | 33(92) | 33(92) | 33(92) | 8 | 3 | 9 | 0 | 0 |
| 0600 | 33(91) | 33(91) | 33(91) | 8 | 3 | 9 | 55 | 18 |
| 0700 | 33(92) | 33(92) | 33(92) | 8 | 3 | 9 | 270 | 85 |
| 0800 | 36(97) | 36(97) | 36(97) | 6 | 3 | 9 | 505 | 160 |
| 0900 | 41(105) | 41(106) | 41(106) | 6 | 3 | 9 | 730 | 231 |
| 1000 | 43(110) | 44(112) | 44(112) | 5 | 4 | 14 | 915 | 291 |
| 1100 | 46(115) | 47(117) | 47(117) | 4 | 4 | 14 | 1040 | 330 |
| 1200 | 48(119) | 49(120) | 49(121) | 4 | 4 | 14 | 1120 | 355 |
| 1300 | 51(123) | 52(125) | 52(126) | 3 | 4 | 14 | 1120 | 355 |
| 1400 | 52(126) | 53(128) | 54(129) | 3 | 4 | 14 | 1040 | 330 |
| 1500 | 53(127) | 54(129) | 54(130) | 3 | 4 | 14 | 915 | 291 |
| 1600 | 53(128) | 54(130) | 55(131) | 3 | 4 | 14 | 730 | 231 |
| 1700 | 53(127) | 54(129) | 54(130) | 3 | 4 | 14 | 505 | 160 |
| 1800 | 52(125) | 53(127) | 53(128) | 3 | 4 | 14 | 270 | 85 |
| 1900 | 49(121) | 50(122) | 51(123) | 3 | 4 | 14 | 55 | 18 |
| 2000 | 45(113) | 46(114) | 46(115) | 4 | 4 | 14 | 0 | 0 |
| 2100 | 43(110) | 44(114) | 44(111) | 5 | 4 | 14 | 0 | 0 |
| 2200 | 41(106) | 42(107) | 42(108) | 6 | 4 | 14 | 0 | 0 |
| 2300 | 39(103) | 40(104) | 40(104) | 6 | 4 | 14 | 0 | 0 |
| 2400 | 38(101) | 39(102) | 39(102) | 6 | 3 | 9 | 0 | 0 |
4.1.2 High temperature with high humidity
Since very high absolute humidities can occur with even higher temperatures than those in paragraph 4.1.3, this paragraph provides guidance on the joint occurrence of high humidities with temperatures above 41°C (106°F). These extremes occur in the coastal deserts surrounding the Persian Gulf, Gulf of Aden, and the Red Sea. Abadan, Iran was determined as representative of the world's most extreme high temperature, high-humidity environment.
- a. Highest Recorded. The highest recorded temperature of 48.3°C (119°F) with a concurrent dew point of 29.4°C (85°F) was recorded at Abadan, Iran on 24 July 1953.
- b. Frequency of Occurrence. Seven years of data for Abadan, Iran were analyzed to determine the following joint frequencies of occurrence shown in Table IV:
Table IV. Abadan frequencies of occurrence of high temperatures with high humidity
| Temperature °C (°F) | Dew Point °C (°F) | ||
|---|---|---|---|
| 1 percent | 5 percent | 10 percent | |
| 46.1 (115) | 27.2 (81) | 21.7 (71) | * |
| 43.3 (110) | 27.8 (82) | 24.4 (76) | 20 (68) |
*The indicated temperature does not occur often.
- c. Long-term Extremes. The 7 years of data available for Abadan were insufficient for extreme value analysis to determine the long-term extremes in the same format presented for most other elements. Therefore, the 0.1-percent joint values of temperature and dew point were calculated to satisfy more stringent design requirements. Temperatures and respective dew points having a joint frequency of occurrence of 0.1 percent are: 48.9°C (120°F) with a dew point of 25.6°C (78°F), 46.1°C (115°F) with a dew point of 31.1°C (88°F), and 43.3°C (110°F) with a dew point of 31.1°C (88°F).
4.1.3 High absolute humidity
Absolute humidity is the mass of water vapor in a specified volume of air. The dew point, the temperature at which condensation would occur if the air was cooled at constant pressure, is the observed meteorological element used to calculate the absolute humidity. Since the amount of water vapor the air can hold increases with temperature, areas with the highest absolute humidities are hot locations (usually at the edge of a desert) adjacent to very warm bodies of water. (See paragraph 6.1, reference a, paragraph 5.1.3 for further explanation.)
- a. Highest Recorded. The highest accepted dew point observation is 35°C (95°F) and occurred at Dhahran, Saudi Arabia on 8 July 2003. The previous high was 34°C (93°F), (100 percent RH and 93.2 °F) recorded in July (exact date unknown) at Sharjah, Arabia, on the shore of the Persian Gulf.
- b. Frequency of Occurrence. The highest dew points in the world were recorded along the narrow deserts of the Red Sea, Gulf of Aden, and the Persian Gulf eastward to the northern Arabian Sea. In this area, Abadan, Iran, was found to have the highest dew point occurring 1 percent of the time in the worst month, 31°C (88°F).
Although Abadan has the highest 1-percent extreme, extremes for higher percents are found in regions where the dew points are somewhat lower but more nearly constant. The 5-, 10-, and 20-percent dew point extremes are 30°C (86°F), 29°C (84°F), and 28°C (83°F) respectively. These values were determined using data from Belize City, Belize (see MIL-HDBK-310, Table V).
Using the Abadan data, a synthetic cycle associated with the 1-percent dew point extreme was constructed and is given in Table IV. It shows the 1-percent dew point of 31°C (88°F) persisting for 7 hrs, a maximum temperature of 41°C (105°F) and a dew point of 29°C (84°F) or higher for the full cycle.
- c. Long-term Extremes. The long term extreme occurrence of dew point is about 2°C (3.6 °F) more than the 1-percent value. This may not be as detrimental to materiel as a somewhat lower dew point occurring for an extended period of time. The long term extreme will be a repetition of a daily cycle typical of a location experiencing high absolute humidities for extended periods of time.
4.1.3.1 Hot-humid cycle (B3)
- a. Location. These severe dewpoint conditions occur only along a very narrow coastal strip (probably less than 8 km (5 miles)) bordering bodies of water with high surface temperatures, specifically the Persian Gulf and the Red Sea. The hot-humid cycle will be used as a design condition only for systems intended for use or likely to be used in these limited areas. Areas reporting these highest worldwide dewpoints may also experience hot-dry conditions at other times.
b. Temperature, humidity, solar radiation
- (1) Operational conditions. On days with extremely high dewpoints (high absolute humidity), a cycle such as that in Table V may occur, along with wind speeds between 2.4 and 5.2 mps (8 and 17 fps), and a maximum ground surface temperature of 54°C (130°F).
- (2) Storage and transit conditions. Induced storage temperatures are presumed to be the same as those for the hot-dry cycle, although relative humidities in the enclosed space are considerably higher.
Table V. Hot climatic design type B3: Hot-humid daily cycle.
| Local Time | OPERATIONAL CONDITIONS (Natural Environment) | STORAGE AND TRANSIT CONDITIONS | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Ambient Air Temperature | Solar Radiation | Relative Humidity | Dewpoint Temperature | Induced Air Temperature | Relative Humidity | |||||
| °C | °F | W/m² | Bph | Percent | °C | °F | °C | °F | Percent | |
| 0100 | 31 | 88 | 0 | 0 | 88 | 29 | 84 | 35 | 95 | 67 |
| 0200 | 31 | 88 | 0 | 0 | 88 | 29 | 84 | 34 | 94 | 72 |
| 0300 | 31 | 88 | 0 | 0 | 88 | 29 | 84 | 34 | 94 | 75 |
| 0400 | 31 | 88 | 0 | 0 | 88 | 29 | 84 | 34 | 93 | 77 |
| 0500 | 31 | 88 | 0 | 0 | 88 | 29 | 84 | 33 | 92 | 79 |
| 0600 | 32 | 90 | 45 | 15 | 85 | 29 | 85 | 33 | 91 | 80 |
| 0700 | 34 | 93 | 315 | 100 | 80 | 30 | 86 | 36 | 97 | 70 |
| 0800 | 36 | 96 | 560 | 177 | 76 | 31 | 87 | 40 | 104 | 54 |
| 0900 | 37 | 98 | 790 | 251 | 73 | 31 | 88 | 44 | 111 | 42 |
| 1000 | 38 | 100 | 950 | 302 | 69 | 31 | 88 | 51 | 124 | 31 |
| 1100 | 39 | 102 | 1035 | 328 | 65 | 31 | 88 | 57 | 135 | 24 |
| 1200 | 40 | 104 | 1080 | 343 | 62 | 31 | 88 | 62 | 144 | 17 |
| 1300 | 41 | 105 | 1000 | 317 | 59 | 31 | 88 | 66 | 151 | 16 |
| 1400 | 41 | 105 | 885 | 280 | 59 | 31 | 88 | 69 | 156 | 15 |
| 1500 | 41 | 105 | 710 | 225 | 59 | 31 | 88 | 71 | 160 | 14 |
| 1600 | 41 | 105 | 465 | 147 | 59 | 31 | 88 | 69 | 156 | 16 |
| 1700 | 39 | 102 | 210 | 66 | 65 | 31 | 88 | 66 | 151 | 18 |
| 1800 | 37 | 99 | 15 | 4 | 69 | 31 | 87 | 63 | 145 | 21 |
| 1900 | 36 | 97 | 0 | 0 | 73 | 31 | 87 | 58 | 136 | 29 |
| 2000 | 34 | 94 | 0 | 0 | 79 | 30 | 86 | 50 | 122 | 41 |
| 2100 | 33 | 91 | 0 | 0 | 85 | 30 | 86 | 41 | 105 | 53 |
| 2200 | 32 | 90 | 0 | 0 | 85 | 29 | 85 | 39 | 103 | 58 |
| 2300 | 32 | 89 | 0 | 0 | 88 | 29 | 85 | 37 | 99 | 62 |
| 2400 | 31 | 88 | 0 | 0 | 88 | 29 | 84 | 35 | 95 | 63 |
4.2 Controls
The accuracy in providing and measuring vibration environments is highly dependent on fixtures and mountings for the test item, the measurement system, and the exciter control strategy. Ensure all instrumentation considerations are in accordance with the best practices available (see paragraph 6.1, reference j). Careful design of the test set up, fixtures, transducer mountings, and wiring, along with good quality control will be necessary to meet the tolerances of paragraph 4.2.2 below.
528.1-4.2 Basic climatic design type
Four daily cycles represent conditions that may be found in areas where the basic climatic design type prevails. Two of these cycles represent high humidity conditions and two represent the extreme temperatures of the basic set of design values.
4.2.1 Control Strategy
Select a control strategy that will provide the required vibration at the required location(s) in or on the test item. Base this selection on the characteristics of the vibration to be generated and platform/ equipment interaction (see paragraph 1.3b above and Method 514.8, Annex A, paragraph 2.4). Generally, a single strategy is appropriate. There are cases where multiple strategies are used simultaneously.
528.1-4.2.1 High relative humidity with high temperature
Relative humidity (RH) indicates the degree of saturation of the air. It is the ratio of the actual vapor pressure of the air to the saturation vapor pressure.
The maximum RH of 100 percent is encountered in nature at temperatures up to about 30 to 32°C (86 to 90°F) directly over water surfaces adjacent to coastal deserts. Over much of the world’s tropical areas, 100 percent RH with temperatures up to 26°C (79°F) occurs quite frequently. One hundred percent RH is closely approached in tropical jungles.
- a. Highest Recorded. High recorded surface relative humidities of 100 percent with fairly high temperatures are common in the moist tropics. An observed RH of 100 percent with a temperature of 30°C (86°F) at Dobochura, Papua, New Guinea has undoubtedly occurred at other locations in the moist tropics.
- b. Frequency of Occurrence. Large open areas of the tropics have high relative humidities with high temperature. Giving the 1-percent high RH is meaningless for design, since the 5-percent value is as high
as 100 percent in many areas. The conditions shown in Table VII (B2 – Variable High Humidity) may be found in open moist tropical areas during any month of the year. Examples of stations with such extremes are Calcutta (India), Seno (Laos), Kampot (Cambodia), Hanoi (North Vietnam), Nanking (China), Kwajalein Atoll, Paramaribo (Surinam), and Georgetown (Guyana).
- c. Long-term Extremes. As a minimum, materiel should be designed for long-term exposure to nearly constant high RH and high temperature of Table VI (B1 – Constant High Humidity). Such a daily cycle prevails in jungles under the canopy of tropical rainforests. The primary feature of this condition is the long duration of RH at and above 95 percent. These conditions may occur on several days during any month of the year, but are more prevalent during rainy seasons. Solar radiation is negligible for this cycle.
4.2.1.1 Acceleration Input Control Strategy
Input control is the traditional approach to vibration testing. Control accelerometers are mounted on the fixture at the test item mounting points. Exciter motion is controlled with feedback from the control accelerometer(s) to provide defined vibration levels at the fixture/test item interface. Where appropriate, the control signal can be the average (weighted average or maxima) of the signals from more than one test item/fixture accelerometer. This represents the platform input to the equipment, and assumes that the equipment does not influence platform vibration.
4.2.1.2 Force Control Strategy
Dynamic force gages are mounted between the exciter/fixture and the test item. Exciter motion is controlled with feedback from the force gages to replicate field measured interface forces. This strategy is used where the field (platform/ equipment) dynamic interaction is significantly different from the laboratory (exciter/test item) dynamic interaction. This form of control inputs the correct field-measured forces at the interface of the laboratory vibration
MIL-STD-810H
METHOD 528.1
exciter and test item. This strategy is used to prevent overtest or undertest of equipment mounts at the lowest structural resonances that may otherwise occur with other forms of control.
4.2.1.3 Acceleration Limit Strategy
Input vibration criteria are defined as in paragraph 4.2.1.1. In addition, vibration response limits at specific points on the equipment are defined (typically based on field measurements). Monitoring accelerometers are located at these points. The test item is excited as in paragraph 4.2.1.1 using test item mounting point accelerometer signals to control the exciters. The input criteria are experimentally modified as needed to limit responses at the monitoring accelerometers to the predefined limits. Changes to the specified input criteria are limited in frequency bandwidth and in level to the minimum needed to achieve the required limits.
4.2.1.4 Acceleration Response Control Strategy
Vibration criteria are specified for specific points on, or within the test item. Control accelerometers are mounted at the vibration exciter/fixture interface. Monitoring accelerometers are mounted at the specified points within the item. An arbitrary low level vibration, controlled with feedback from the control accelerometers, is input to the test item. The input vibration is experimentally adjusted until the specified levels are achieved at the monitoring accelerometers. This strategy is commonly used with assembled aircraft stores where store response to the dynamic environment is measured or estimated. It is also applicable for other equipment when field measured response data are available.
4.2.1.5 Waveform Control Strategy
This strategy is discussed in Method 525.2.
4.2.2 Tolerances
Use the following tolerances unless otherwise specified. In cases where these tolerances cannot be met, achievable tolerances should be established and agreed to by the cognizant engineering authority and the customer prior to initiation of test. Protect measurement transducer(s) to prevent contact with surfaces other than the mounting surface(s).
528.1-4.2.2 High humidity daily cycles
- a. Location. Basic high humidity conditions are found most often in tropical areas, although they occur briefly or seasonally in the mid-latitudes. One of the two high humidity cycles (B1 - constant high humidity) represents conditions in the heavily forested areas in the tropics under heavy cloud cover, where nearly constant conditions may prevail during rainy and wet seasons. Exposed materiel is likely to be constantly wet or damp for many days at a time. The other daily cycle (B2 - variable high humidity) represents conditions found in the open in tropical areas, with clear skies or intermittent cloudiness. In the first cycle, exposed materiel is likely to be constantly wet or damp for many days at a time. In the second cycle, exposed items are subject to alternate wetting and drying. Both conditions promote severe deterioration in materiel. The one that is most important, as shown below, depends on the nature of the materiel involved.
| Type Material | Type of Site with the Highest Deterioration Rates |
|---|---|
| Elastomers | Open |
| Polymers | Open |
| Textiles | Forest |
| Metals | Coastal swamp (mangrove) and forest |
- (1) The climate station selected for these categories was Majuro, Marshall Islands (7o05’ N, 171o23’E). The station is located Weather Services Building at the Majuro Airport. This site is a first-order U.S. weather reporting station. Majuro was selected over 12 available candidate stations from around the world initially because it possessed the required temperature and precipitation characteristics (to create high relative humidity) for the B1 category, and it met the criteria for data availability and quality.
- (2) On the average, Majuro receives over 130” (3,300 mm) of rainfall annually. Over 250 days experience rainfall >= 0.254mm (0.01”) and over 310 days experience rainfall >= trace. Ten years of continuous data were used for the analysis (Period of Record (POR): 1973-1982).
- (3) Groupings of consecutive days of rainfall were then extracted. The longest continuous streak of consecutive days >= trace was 51. A cumulative frequency curve was then created. The recommended duration value of 45 days represents the 99th percentile value (actual value = 98.64percent).
MIL-STD-810H PART THREE
4.2.2.1 Acceleration Spectral Density
Carefully examine field measured response probability density information for non-Gaussian behavior. In particular, determine the relationship between the measured field response data and the laboratory replicated data relative to three sigma peak limiting that may be introduced in the laboratory test. The random vibration testing is restricted to combatants with skewed propellers. The alternating thrust of these propellers cannot exceed ±1.5 percent of full power mean thrust.
- a. Vibration environment. The following discussion relates the measured vibration level to the specification level and, like the control system, does not consider any measurement uncertainty. The test tolerance should be kept to the minimum level possible considering the test item, fixturing, and spectral shape. Test tolerances of less than ±2 dB are usually readily attainable with small, compact test items (such as small and medium sized rectangular electronic packages), well-designed fixtures, and modern control equipment. When test items are large or heavy, when fixture resonances cannot be eliminated, or when steep slopes (> 20 dB/octave) occur in the spectrum, these tolerances may have to be increased. When increases are required, exercise care to ensure the selected tolerances are the minimum attainable, and that attainable tolerances are compatible with test objectives. In any case, tolerances should not exceed ±3 dB. These tolerances should be limited to a maximum of 5 percent of the test frequency range. Otherwise, change the tests, fixtures, or facilities so test objectives can be met. The rms level of the vibration test should not deviate more than ±10 percent from the required level.
- b. Vibration measurement. Use a vibration measurement system that can provide acceleration spectral density measurements within ±0.5 dB of the vibration level at the transducer mounting surface (or transducer target mounting surface) over the required frequency range. Do not use a measurement bandwidth that exceeds 2.5 Hz at 25 Hz or below, or 5 Hz at frequencies above 25 Hz. Use a frequency resolution appropriate for the application (i.e., generally in wheeled vehicles, a resolution of 1 Hz is sufficient).
- c. Swept narrow-band random on random vibration tests may require lesser degrees of freedom due to sweep time constraints.
MIL-STD-810H
METHOD 528.1
- d. Root mean square (RMS) “g”. RMS levels are useful in monitoring vibration tests since RMS can be monitored continuously, whereas measured spectra are available on a delayed, periodic basis. Also, RMS values are sometimes useful in detecting errors in test spectra definition.
4.2.2.2 Peak Sinusoidal Acceleration
- a. Vibration environment. Validate the accelerometer(s) sensitivity before and after testing. Ensure the peak sinusoidal acceleration at a control transducer does not deviate from that specified by more than ±10 percent over the specified frequency range.
- b. Vibration measurement. Ensure the vibration measurement system provides peak sinusoidal acceleration measurements within ±5 percent of the vibration level at the transducer mounting surface (or transducer target mounting surface) over the required frequency range.
4.2.2.3 Frequency Measurement
Ensure the vibration measurement system provides frequency measurements within ±1.25 percent at the transducer mounting surface (or transducer target mounting surface) over the required frequency range.
4.2.2.4 Cross Axis Sensitivity
Ensure vibration acceleration in two axes mutually orthogonal and orthogonal to the drive axis is less than or equal to 0.45 times the acceleration (0.2 times the spectral density) in the drive axis over the required frequency range. In a random vibration test, the cross axis acceleration spectral density often has high but narrow peaks. Consider these in tailoring cross-axis tolerances.
4.2.3 Temperature, humidity, solar radiation (constant high humidity cycle (B1))
- a. Operational conditions. Relative humidity above 95 percent in association with a nearly constant temperature at 24°C (75°F) persists for periods of several days (Table VI).
- b. Storage and transit conditions. Relative humidity above 95 percent in association with nearly constant 27°C (80°F) temperature occurs for periods of a day or more.
Table VI. Basic climatic design type B1: Constant high humidity daily cycle.
| Local Time | OPERATIONAL CONDITIONS (Natural Environment) | STORAGE AND TRANSIT CONDITIONS | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Ambient Air Temperature | Solar Radiation | Relative Humidity | Dewpoint Temperature | Induced Air Temperature | Relative Humidity | |||||
| °C | °F | Bph | W/m² | Percent | °C | °F | °C | °F | Percent | |
| 0100 | Nearly constant at 24°C (75°F) throughout the 24 hours. | Negligible | 100 | 24 | 75 | Nearly constant at 27°C (80°F) Throughout the 24 hours. | Same as operational conditions. | |||
| 0200 | 100 | 24 | 75 | |||||||
| 0300 | 100 | 24 | 75 | |||||||
| 0400 | 100 | 24 | 75 | |||||||
| 0500 | 100 | 24 | 75 | |||||||
| 0600 | 100 | 24 | 75 | |||||||
| 0700 | 98 | 23 | 74 | |||||||
| 0800 | 97 | 23 | 74 | |||||||
| 0900 | 95 | 23 | 74 | |||||||
| 1000 | 95 | 23 | 74 | |||||||
| 1100 | 95 | 23 | 74 | |||||||
| 1200 | 95 | 23 | 74 | |||||||
| 1300 | 95 | 23 | 74 | |||||||
| 1400 | 95 | 23 | 74 | |||||||
| 1500 | 95 | 23 | 74 | |||||||
| 1600 | 95 | 23 | 74 | |||||||
| 1700 | 95 | 23 | 74 | |||||||
| 1800 | 95 | 23 | 74 | |||||||
| 1900 | 97 | 23 | 74 | |||||||
| 2000 | 98 | 23 | 74 | |||||||
| 2100 | 100 | 24 | 75 | |||||||
| 2200 | 100 | 24 | 75 | |||||||
| 2300 | 100 | 24 | 75 | |||||||
| 2400 | 100 | 24 | 75 | |||||||
4.2.4 Temperature, humidity, solar radiation (variable high humidity cycle (B2))
- a. Operational conditions. The daily cycle outlined in Table VII has a maximum ambient air temperature of 35°C (95°F) for 2 hours. The maximum solar radiation load of 907 W/m² (307 Bph) for not more than 2 hours, is accompanied by wind speeds of less than 2 mps (7 fps) and a maximum ground surface temperature of 54°C (130°F).
- b. Storage and transit conditions. See storage and transit conditions associated with the hot-humid daily cycle of the hot climatic design type.
Table VII. Basic climatic design type B2: Variable high humidity daily cycle.
| Local Time | OPERATIONAL CONDITIONS (Natural Environment) | STORAGE AND TRANSIT CONDITIONS | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Ambient Air Temperature | Solar Radiation | Relative Humidity | Dewpoint Temperature | Induced Air Temperature | Relative Humidity | |||||
| °C | °F | W/m² | Bph | Percent | °C | °F | °C | °F | Percent | |
| 0100 | 27 | 80 | 0 | 0 | 100 | 27 | 80 | 33 | 91 | 69 |
| 0200 | 26 | 79 | 0 | 0 | 100 | 26 | 79 | 32 | 90 | 70 |
| 0300 | 26 | 79 | 0 | 0 | 100 | 26 | 79 | 32 | 90 | 71 |
| 0400 | 26 | 79 | 0 | 0 | 100 | 26 | 79 | 31 | 88 | 72 |
| 0500 | 26 | 78 | 0 | 0 | 100 | 26 | 78 | 30 | 86 | 74 |
| 0600 | 26 | 78 | 45 | 15 | 100 | 26 | 78 | 31 | 88 | 75 |
| 0700 | 27 | 81 | 230 | 73 | 94 | 26 | 79 | 34 | 93 | 64 |
| 0800 | 29 | 84 | 435 | 138 | 88 | 27 | 80 | 38 | 101 | 54 |
| 0900 | 31 | 87 | 630 | 200 | 82 | 27 | 81 | 42 | 107 | 43 |
| 1000 | 32 | 89 | 795 | 252 | 79 | 28 | 82 | 45 | 113 | 36 |
| 1100 | 33 | 92 | 900 | 286 | 77 | 28 | 83 | 51 | 124 | 29 |
| 1200 | 34 | 94 | 970 | 307 | 75 | 29 | 84 | 57 | 134 | 22 |
| 1300 | 34 | 94 | 970 | 307 | 74 | 29 | 84 | 61 | 142 | 21 |
| 1400 | 35 | 95 | 900 | 286 | 74 | 29 | 85 | 63 | 145 | 20 |
| 1500 | 35 | 95 | 795 | 252 | 74 | 30 | 86 | 63 | 145 | 19 |
| 1600 | 34 | 93 | 630 | 200 | 76 | 29 | 85 | 62 | 144 | 20 |
| 1700 | 33 | 92 | 435 | 138 | 79 | 29 | 84 | 60 | 140 | 21 |
| 1800 | 32 | 90 | 230 | 73 | 82 | 29 | 84 | 57 | 134 | 22 |
| 1900 | 31 | 88 | 45 | 15 | 86 | 28 | 83 | 50 | 122 | 32 |
| 2000 | 29 | 85 | 0 | 0 | 91 | 28 | 83 | 44 | 111 | 43 |
| 2100 | 28 | 83 | 0 | 0 | 95 | 28 | 82 | 38 | 101 | 54 |
| 2200 | 28 | 82 | 0 | 0 | 96 | 27 | 81 | 35 | 95 | 59 |
| 2300 | 27 | 81 | 0 | 0 | 100 | 27 | 81 | 34 | 93 | 63 |
| 2400 | 27 | 80 | 0 | 0 | 100 | 27 | 80 | 33 | 91 | 68 |
4.2.5 Basic hot daily cycle (A2)
- a. Location. Basic hot conditions exist in many parts of the world extending outward from the areas of hot-dry conditions in the United States, Mexico, northern Africa, southwestern Asia, India, Pakistan, and southern Spain in the northern hemisphere, and smaller sections of South America, southern Africa, and Australia in the southern hemisphere.
b. Temperature, humidity, solar radiation
- (1) Operational conditions. Design criteria are: eight continuous hours with an ambient air temperature above 41°C (105°F) with an extreme temperature of 43°C (110°F) for not more than 3 hours; a maximum ground surface temperature of 60°C (140°F); solar radiation (horizontal surface) at a rate of 1120 W/m² (355 Bph) for not more than 2 hours (not concurrent with the extreme temperature); a wind speed between 3 and 5 mps (10 and 16 fps) during the period with temperature above 41°C (105°F); and a relative humidity of approximately 14 percent concurrent with the high temperatures (Table VIII).
For elevations of 914 to 3048m (3,000 to 10,000 feet), the ground surface temperature and wind remain the same. Ambient air temperatures, however, decrease 9.1°C per 1,000 m (5°F per 1,000 feet) and solar radiation increases at a rate of 43 W/m² per 1,000m (4 Bph per 1,000 feet).
MIL-STD-810H
PART THREE
(2) Storage and transit conditions. Design criteria are: Four continuous hours with an induced air temperature above 60°C (140°F) with relative humidity less than 8 percent; use an air temperature extreme of 63°C (145°F) for not more than 2 hours without benefit of solar radiation and with negligible wind (Table VIII).
Table VIII. Basic climatic design type A2: Basic hot daily cycle.
| Local Time | OPERATIONAL CONDITIONS (Natural Environment) | STORAGE AND TRANSIT CONDITIONS | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Ambient Air Temperature | Solar Radiation | Relative Humidity | Dewpoint Temperature | Induced Air Temperature | Relative Humidity | |||||
| °C | °F | W/m² | Bph | Percent | °C | °F | °C | °F | Percent | |
| 0100 | 33 | 91 | 0 | 0 | 36 | 15 | 61 | 33 | 91 | 36 |
| 0200 | 32 | 90 | 0 | 0 | 38 | 16 | 60 | 32 | 90 | 38 |
| 0300 | 32 | 90 | 0 | 0 | 41 | 17 | 63 | 32 | 90 | 41 |
| 0400 | 31 | 88 | 0 | 0 | 44 | 17 | 62 | 31 | 88 | 44 |
| 0500 | 30 | 86 | 0 | 0 | 44 | 17 | 62 | 30 | 86 | 44 |
| 0600 | 30 | 86 | 55 | 18 | 44 | 17 | 62 | 31 | 88 | 43 |
| 0700 | 31 | 88 | 270 | 85 | 41 | 16 | 61 | 34 | 93 | 37 |
| 0800 | 34 | 93 | 505 | 160 | 34 | 16 | 61 | 38 | 101 | 30 |
| 0900 | 37 | 99 | 730 | 231 | 29 | 17 | 62 | 42 | 107 | 23 |
| 1000 | 39 | 102 | 915 | 291 | 24 | 14 | 58 | 45 | 113 | 17 |
| 1100 | 41 | 106 | 1040 | 330 | 21 | 14 | 58 | 51 | 124 | 14 |
| 1200 | 42 | 107 | 1120 | 355 | 18 | 13 | 55 | 57 | 134 | 8 |
| 1300 | 43 | 109 | 1120 | 355 | 16 | 11 | 52 | 61 | 142 | 6 |
| 1400 | 43 | 110 | 1040 | 330 | 15 | 11 | 52 | 63 | 145 | 6 |
| 1500 | 43 | 110 | 915 | 291 | 14 | 10 | 50 | 63 | 145 | 5 |
| 1600 | 43 | 110 | 730 | 231 | 14 | 10 | 50 | 62 | 144 | 6 |
| 1700 | 43 | 109 | 505 | 160 | 14 | 9 | 49 | 60 | 140 | 6 |
| 1800 | 42 | 107 | 270 | 85 | 15 | 9 | 49 | 57 | 134 | 6 |
| 1900 | 40 | 104 | 55 | 18 | 17 | 10 | 50 | 50 | 122 | 10 |
| 2000 | 38 | 100 | 0 | 0 | 20 | 11 | 51 | 44 | 111 | 14 |
| 2100 | 36 | 97 | 0 | 0 | 22 | 11 | 51 | 38 | 101 | 19 |
| 2200 | 35 | 95 | 0 | 0 | 25 | 12 | 54 | 35 | 95 | 25 |
| 2300 | 34 | 93 | 0 | 0 | 28 | 12 | 54 | 34 | 93 | 28 |
| 2400 | 33 | 91 | 0 | 0 | 33 | 14 | 58 | 33 | 91 | 33 |
4.2.6 Basic cold daily cycle (C1)
- a. Location. Extensive basic cold conditions are found only in the Northern Hemisphere south of the coldest areas and on high latitude coasts (e.g., the southern coast of Alaska) where maritime effects prevent occurrence of very low temperatures, as well as southern Canada, the coast of southern Greenland, northern Europe, the former Soviet Union, and central Asia. Small areas of basic cold weather conditions may be found at high elevations in lower latitudes.
b. Temperature, humidity, solar radiation. (1) Operational conditions
Design conditions are: five continuous hours with an ambient air temperature of -31°C (-25°F); a minimum ground surface temperature of -37°C (-35°F); wind speed less than 5 mps (16 fps); negligible solar radiation (horizontal surface); and humidity tending toward saturation (Table IX). Saturation is the result of the extremely low temperatures. The absolute humidity and vapor pressure are very low when these
temperatures prevail. Although not typical, wind speeds greater than 16 fps may be associated with temperatures of -31°C (-25°F).
(2) Storage and transit conditions. Design criteria are five continuous hours with an induced air temperature of -33°C (-28°F) with no wind or solar radiation, and humidity tending toward saturation Table IX).
Table IX. Basic climatic design type C1; Cold daily cycle.
| Local Time | OPERATIONAL CONDITIONS (Natural Environment) | STORAGE AND TRANSIT CONDITIONS | ||||||
|---|---|---|---|---|---|---|---|---|
| Ambient Air Temperature | Solar Radiation | Relative Humidity | Induced Air Temperature | Relative Humidity | ||||
| °C | °F | W/m² | Bph | Percent | °C | °F | Percent | |
| 0100 | -31 | -24 | Negligible During Low Temperature Periods | Tending Towards Saturation | -33 | -27 | ||
| 0200 | -32 | -25 | -33 | -28 | Tending Toward Saturation | |||
| 0300 | -32 | -25 | -33 | -28 | ||||
| 0400 | -32 | -25 | -33 | -28 | ||||
| 0500 | -32 | -25 | -33 | -28 | ||||
| 0600 | -32 | -25 | -33 | -28 | ||||
| 0700 | -30 | -22 | -33 | -27 | ||||
| 0800 | -28 | -18 | -33 | -27 | ||||
| 0900 | -26 | -15 | -32 | -26 | ||||
| 1000 | -24 | -12 | -31 | -24 | ||||
| 1100 | -22 | -8 | -30 | -22 | ||||
| 1200 | -21 | -5 | -28 | -19 | ||||
| 1300 | -21 | -5 | -27 | -17 | ||||
| 1400 | -21 | -6 | -26 | -15 | ||||
| 1500 | -21 | -6 | -25 | -13 | ||||
| 1600 | -22 | -8 | -26 | -15 | ||||
| 1700 | -24 | -11 | -28 | -18 | ||||
| 1800 | -25 | -13 | -29 | -20 | ||||
| 1900 | -26 | -15 | -30 | -22 | ||||
| 2000 | -27 | -17 | -31 | -24 | ||||
| 2100 | -28 | -19 | -32 | -26 | ||||
| 2200 | -29 | -21 | -33 | -27 | ||||
| 2300 | -30 | -22 | -33 | -27 | ||||
| 2400 | -31 | -24 | -33 | -27 | ||||
4.3 Test Interruption
Test interruptions can result from multiple situations. The following paragraphs discuss common causes for test interruptions and recommended paths forward for each. Recommend test recording equipment remain active during any test interruption if the excitation equipment is in a powered state.
528.1-4.3 Cold and severe cold design types
Two daily cycles represent the “Cold” (C2) and “Severe Cold” (C3) climatic design types. The “Cold” design type is more extensive than the “Severe Cold” (see Figure 1), but ensure the LCEP reflects the proper design type before applying either one.
4.3.1 Interruption Due to Laboratory Equipment Malfunction
- a. General. See Part One, paragraph 5.11 of this Standard.
- b. Specific to this Method. When interruptions are due to failure of the laboratory equipment, analyze the failure to determine root cause. It is also strongly advised that both control and response data be evaluated to ensure that no undesired transients were imparted to the test item during the test equipment failure. If the test item was not subjected to an over-test condition as a result of the equipment failure, repair the test equipment or move to alternate test equipment and resume testing from the point of interruption. If the test item was subjected to an over-test condition as a result of the equipment failure, the test engineer or program engineer responsible for the test article should be notified immediately. A risk assessment based on factors such as level and duration of the over-test event, spectral content of the event, cost and availability of test resources, and analysis of test specific issues should be conducted to establish the path forward. See Method 514.8, Annex A, paragraph 2.1 for descriptions of common test types, and a general discussion of test objectives.
528.1-4.3.1 Low temperature
Low temperature extremes result from the optimum combination of several meteorological elements. Long absence of solar radiation, clear skies, a snow cover, and calm air are the most essential requirements, with the ultimate fall in temperature dependent on the duration of these conditions. Since these conditions can exist for extended periods at high-latitude continental areas, there can be much longer durations of cold than high temperatures, that have a diurnal dependence.
MIL-STD-810H
PART THREE
Temperatures presented were observed in standard meteorological instrument shelters. They represent temperatures of free air at about 1.5m (4.9 ft) above the snow surface. Temperatures within a few cm of the surface could be 4 to 5°C (7 to 9°F) colder.
- a. Lowest Recorded. Excluding Antarctica, the generally accepted world's lowest recorded temperature is -68°C (-90°F). It was recorded at Verkhoyansk, USSR (elevation 105m (345 ft)), on 5 and 7 February 1892, and at Ojmjakon, USSR (elevation 660m (2165 ft)) on 6 February 1933.
b.
Frequency of Occurrence.
- Because of insufficient hourly data to determine the distribution of low temperature versus frequency of occurrence on a global basis, a statistical technique was used to estimate percentile temperatures for thousands of locations worldwide. The low temperature analyses were used to determine the areas of the world with the coldest temperatures occurring 1-, 5-, 10-, and 20-percent of the time during the worst month. The 20-percent value was added for this element because the low temperatures associated with lower frequencies are limited in geographical extent.
The coldest areas of the world (excluding Antarctica) are the central part of the Greenland ice cap (approximately 2500-3000m elevation (1.55-1.86 miles)), and Siberia between 62° to 68°N, and 125° to 145°E (less than 800m (0.5 mi) elevation). The 1-, 5-, 10-, and 20-percent temperatures in these areas are -61°C (-78°F), -57°C (-70°F), -54°C (-65°F), and -51°C (-60°F), respectively. A diurnal cycle is not provided because the effect of solar radiation during these extreme conditions is minimal. Duration of very cold temperatures is an important consideration. Studies indicate that during a 24 hour period the maximum temperatures would exceed the percentile temperatures by only about 3°C (5°F)
- c. Long-term Extremes.
Low temperatures that could be expected to occur at least once during 10, 30, and 60 years in the coldest area of the world are -65°C (-78°F), -67°C (-89°F), and -69°C (-92°F), respectively. These values were derived from statistical analysis of 16 years of temperature data from Ojmjakon, USSR. The 60-year value is lower than the recorded extreme because it represents a longer period than the period of actual observations. Table X provides temperature regimes for 32 days with these temperature minima. Typically this is not referred to as a climatic design type. However, the LCEP may delineate the need for these values.
Table X. Monthly cycle of temperature associated with the worldwide
long term low temperature extremes. (See paragraph 4.3.1c.)
| Time | Hours Before and After | Days Before and After | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Period (yrs) | Temp | 0 | 0.5 | 1.5 | 3 | 6 | 12 | 1 | 2 | 4 | 8 | 16 |
| 10 | °C | -66 | -66 | -66 | -65 | -65 | -64 | -63 | -59 | -55 | -49 | -42 |
| °F | -87 | -87 | -87 | -85 | -85 | -83 | -81 | -74 | -67 | -56 | -44 | |
| 30 | °C | -67 | -67 | -67 | -67 | -67 | -66 | -64 | -62 | -57 | -51 | -45 |
| °F | -89 | -89 | -89 | -89 | -89 | -87 | -83 | -80 | -71 | -60 | -49 | |
| 60 | °C | -69 | -69 | -68 | -68 | -67 | -67 | -65 | -63 | -58 | -53 | -47 |
| °F | -92 | -92 | -90 | -90 | -89 | -89 | -85 | -81 | -72 | -63 | -53 | |
MIL-STD-810H
PART THREE
4.3.2 Interruption Due to Test Item Operation Failure
Failure of the test item(s) to function as required during operational checks presents a situation with several possible options. Failure of subsystems often has varying degrees of importance in evaluation of the test item. Selection of option a through c below will be test specific.
- a. The preferable option is to replace the test item with a “new” one and restart the entire test.
- b. An alternative is to replace / repair the failed or non-functioning component or assembly with one that functions as intended, and restart the entire test. A risk analysis should be conducted prior to proceeding since this option places an over-test condition on the entire test item except for the replaced component. If the non-functioning component or subsystem is a line replaceable unit (LRU) whose life-cycle is less than that of the system test being conducted, proceed as would be done in the field by substituting the LRU, and continue from the point of interruption.
- c. For many system level tests involving either very expensive or unique test items, it may not be possible to acquire additional hardware for re-test based on a single subsystem failure. For such cases, a risk assessment
should be performed by the organization responsible for the system under test to determine if replacement of the failed subsystem and resumption of the test is an acceptable option. If such approval is provided, the failed component should be re-tested at the subcomponent level.
NOTE: When evaluating failure interruptions, consider prior testing on the same test item and consequences of such.
528.1-4.3.2 Cold climatic design type (C2)
- a. Location.
Cold conditions are found in the Northern Hemisphere in most of Canada, large sections of Alaska, Greenland, northern Scandinavia, northern Asia, and Mongolia. They can also exist in parts of the Tibetan Plateau of Central Asia. Very small areas of the cold type may be found at higher elevations in both the Northern and Southern Hemispheres (e.g., Alps, Himalayas, and the Andes). (See paragraph 2.2.3.)
b. Temperature, humidity, solar radiation.
- (1) Operational conditions.
Design conditions are: six continuous hours with an ambient air temperature of -46°C (-50°F); a minimum snow surface temperature of -46°C (-51°F), wind speed less than 5 m/s (11 mph); negligible solar radiation (horizontal surface); and relative humidity tending towards saturation (Table XI.
(2) Storage and transit conditions. Same as operational conditions (Table XII).
Table XI. Cold climatic design type C2: Daily cycle
| Local Time | OPERATIONAL CONDITIONS (Natural Environment) | STORAGE AND TRANSIT CONDITIONS | ||||||
|---|---|---|---|---|---|---|---|---|
| Ambient Air Temperature | Solar Radiation | Relative Humidity | Induced Air Temperature | Relative Humidity | ||||
| °C | °F | Bph | W/m² | Percent | °C | °F | Percent | |
| 0100 | -46 | -51 | Negligible | Tending Towards Saturation | -46 | -51 | ||
| 0200 | -46 | -51 | -46 | -51 | Tending Towards Saturation | |||
| 0300 | -46 | -51 | -46 | -51 | ||||
| 0400 | -46 | -51 | -46 | -51 | ||||
| 0500 | -46 | -51 | -46 | -51 | ||||
| 0600 | -46 | -51 | -46 | -51 | ||||
| 0700 | -45 | -49 | -45 | -49 | ||||
| 0800 | -44 | -47 | -44 | -47 | ||||
| 0900 | -43 | -45 | -43 | -45 | ||||
| 1000 | -41 | -42 | -41 | -42 | ||||
| 1100 | -39 | -38 | -39 | -38 | ||||
| 1200 | -37 | -35 | -37 | -35 | ||||
| 1300 | -37 | -35 | -37 | -35 | ||||
| 1400 | -37 | -35 | -37 | -35 | ||||
| 1500 | -37 | -35 | -37 | -35 | ||||
| 1600 | -38 | -36 | -38 | -36 | ||||
| 1700 | -39 | -38 | -39 | -38 | ||||
| 1800 | -39 | -38 | -39 | -38 | ||||
| 1900 | -41 | -42 | -41 | -42 | ||||
| 2000 | -42 | -44 | -42 | -44 | ||||
| 2100 | -43 | -45 | -43 | -45 | ||||
| 2200 | -44 | -47 | -44 | -47 | ||||
| 2300 | -44 | -47 | -44 | -47 | ||||
| 2400 | -45 | -49 | -45 | -49 | ||||
4.3.3 Interruption Due to a Scheduled Event
There are often situations in which scheduled test interruptions will take place. For example, in a tactical transportation scenario, the payload may be re-secured to the transport vehicle periodically (i.e., tie-down straps may be re-secured at the beginning of each day). Endurance testing often represents a lifetime of exposure; therefore it is not realistic to expect the payload to go through the entire test sequence without re-securing the tie-downs as is done in a tactical deployment. Many other such interruptions, to include scheduled maintenance events, are often required over the life-cycle of equipment. Given the cumulative nature of fatigue imparted by dynamic testing, it is acceptable to have test interruptions that are correlated to realistic life-cycle events. All scheduled interruptions should be documented in the test plan and test report.
528.1-4.3.3 Severe cold climatic design type (C3)
- a. Location.
Except for Antarctica that is excluded from consideration because of an international treaty, the severe cold regional type records the world’s lowest temperatures. These conditions are found in the Northern Hemisphere in the interior of Alaska extending into the Yukon in Canada. They also exist in the interior of the northern islands of the Canadian Archipelago, on the Greenland icecap, and in Siberia.
b. Temperature, humidity, solar radiation.
- (1) Operational conditions. The design condition is a minimum temperature of -51°C (-60°F). (For testing purposes, this is a cold soak temperature.) Solar radiation (horizontal surface) is negligible and relative humidity tends toward saturation (because of low temperature, not high absolute humidity or vapor pressure). Wind speeds are less than 5 m/s (11 mph). In rare cases where materiel is designed to operate solely in areas where the cold climatic design type applies, the reverse season, or expected maximum, temperature is 35°C (95°F).
- (2) Storage and transit conditions. Same as (1) above.
- (3) Daily Cycle. No cycle in tabular format is given because temperature, humidity, and solar radiation remain nearly constant throughout the 24-hour period.
4.3.4 Interruption Due to Exceeding Test Tolerances
Exceeding the test tolerances defined in paragraph 4.2.2, or a noticeable change in dynamic response may result in a manual operator initiated test interruption or an automatic interruption when the tolerances are integrated into the control strategy. In such cases, the test item, fixturing, and instrumentation should be checked to isolate the cause.
- a. If the interruption resulted from a fixturing or instrumentation issue, correct the problem and resume the test.
- b. If the interruption resulted from a structural or mechanical degradation of the test item, the problem will generally result in a test failure and requirement to re-test unless the problem is allowed to be corrected during testing. If the test item does not operate satisfactorily, see paragraph 5 for analysis of results and follow the guidance in paragraph 4.3.3 for test item failure.
528.1-4.3.4 High relative humidity with low temperature
High relative humidity in the dry arctic winter is the rule rather than the exception since the loss of heat by radiation during the long nights causes the temperature to drop to the frost point of the air.
- a. Highest Recorded. The highest recorded RH value of 100 percent can be associated with the low temperature extreme given in paragraph 4.3.1a.
- b. Frequency of Occurrence. A value of 100 percent can be associated with the low temperature frequency of occurrence given in paragraph 4.3.1b.
- c. Long-term Extreme. A value of 100 percent can be associated with the low temperature long term extreme given in paragraph 4.3.1c.
4.3.5 Low relative humidity with low temperature. Not available
4.3.6 Low absolute humidity
Since the amount of water vapor that can be contained in air is directly proportional to air temperature, lowest absolute humidities will be found with lowest air temperatures. For the low absolute humidity extremes, dew points (referred to as frost points when below freezing) were determined using low temperature extremes with an assumed relative humidity of 90 percent.
- a. Lowest Recorded. The absolute humidity associated with the low temperature extreme of -68°C (-90°F) (see paragraph 4.3.1a) and 90-percent relative humidity is assumed. This corresponds to a frost point of -68.4°C (-91°F).
- b. Frequency of Occurrence. The absolute humidities associated with the low temperature extreme values (see paragraph 4.3.1b) and 90-percent relative humidity are assumed. For the 1-percent low temperature of -61°C (-78°F), this corresponds to a frost point of -62°C (-79°F).
- c. Long-term Extremes. The absolute humidities associated with the low temperature extremes (see paragraph 4.3.1c) and 90-percent relative humidity are assumed. For at least one occurrence in 10, 30, and 60 years this corresponds to frost points of -66.1°C (-87°F), -67.8°C (-90°F), and -69.5°C (-93°F) respectively.