WARNING: Refer to the supplier's Safety Data Sheet (SDS) or equivalent for health hazard data. Exposure to silica flour (ground quartz) can cause silicosis; other material may cause adverse health effects.
NOTE: Unless the requirements documents indicate otherwise, if the following test procedure is interrupted because of work schedules, etc., maintaining the test item at the test temperature for the time required will facilitate completion of the test when resumed. If the temperature is changed, before continuing the test, re-stabilize the test item at the temperature of the last successfully completed period before the interruption.
CAUTION: When temperature conditioning, ensure the total test time at elevated temperatures does not exceed the life expectancy of any safety critical materials. This is particularly applicable to energetic materials (see Part One, paragraph 5.19).
Step 1. With the test item in the chamber and stabilized at standard ambient temperature, adjust the air velocity to 8.9 ±1.3 m/s (1750 ±250 ft/min), or as otherwise determined from the test plan. Adjust the relative humidity to less than 30% and maintain it throughout the test.
Step 2. Adjust the dust feed control for a dust concentration of 10.6 ±7 g/m³ (0.3 ±0.2 g/ft³)
Step 3. Unless otherwise specified, maintain the conditions of Steps 1 and 2 for at least 6 hours. If required, periodically reorient the test item to expose other vulnerable faces to the dust stream. If required, perform dust removal when the test item is reoriented (See paragraph 4.1.1.9). SEE THE ABOVE WARNING REGARDING HEALTH HAZARDS. If required, operate the test item in accordance with the test plan. If the test item fails to operate as intended, follow the guidance in paragraph 4.2.3.3.2. Otherwise proceed to Step 4.
Step 4. Stop the dust feed. (See paragraph 4.1.1.7.) If required, operate the test item in accordance with the test plan. Reduce the test section air velocity to 1.5 ±1 m/s (300 ±200 ft/min) and adjust the temperature to the required high operational temperature (see paragraph 4.1.1.1), or as otherwise determined from the test plan. The rate of temperature change shall be no greater than 3°C/min (5.4°F/min).
Step 5. Maintain the Step 4 conditions for a minimum of 1 hour following test item temperature stabilization.
Step 6. Adjust the air velocity to that used in Step 1, and restart the dust feed to maintain the dust concentration as in Step 2.
Step 7. Continue the exposure for at least 6 hours or as otherwise specified. If required perform the following:
a. Periodically reorient the test item to expose other vulnerable faces to the dust stream.
b. Perform dust removal when the test item is reoriented. See paragraph 4.1.1.9. Take photographs prior to and following dust removal.
c. Operate and/or manipulate the test item in accordance with the test plan. If the test item fails to operate as intended, follow the guidance in paragraph 4.2.3.3.2. Otherwise proceed to Step 8.
SEE THE ABOVE WARNING REGARDING HEALTH HAZARDS
Step 8. Stop the dust feed, stop or reduce the air speed to no greater than 2.5 m/s (500 ft/min), and allow the test item to return to standard ambient conditions at a rate not to exceed 3 °C/min (5 °F/min). Stop any air flow and allow the dust to settle (possibly up to 1 hour).
Step 9. Photograph the test item to document dust accumulation.
Step 10. Remove accumulated dust from the test item by brushing or wiping, taking care to avoid introduction of additional dust or disturbing any that may have already entered the test item. See paragraph 4.1.1.9. Do NOT remove dust by either air blast or vacuum cleaning unless these methods are likely to be used in service. SEE THE ABOVE WARNING REGARDING HEALTH HAZARDS.
Step 11. Inspect the test item for dust penetration, giving special attention to bearings, seals, lubricants, filters, ventilation points, etc. Document the results.
Step 12. Perform an operational check in accordance with the approved test plan, and document the results for comparison with pretest data. See paragraph 5.1 for analysis of results.
- Step 13. If required, clean the test item further to ensure that personnel that will be handling or occupying the test item are not exposed to unnecessary health hazards.