84.153—Airflow resistance test, Type A and Type AE supplied-air respirators; minimum requirements.
(a)
Airflow resistance will be determined when the respirator is completely assembled with the respiratory-inlet covering, the air-supply device, and the maximum length of air-supply hose coiled for one-half its length in loops 1.5 to 2.1 m. (5 to 7 feet) in diameter.
(b)
The inhalation resistance, drawn at the rate of 85 liters (3 cubic feet) per minute when the blower is not operating or under any practical condition of blower operation shall not exceed the following amounts:
| Maximum length of hose for which respirator is approved | Maximum resistance, water column height | ||
|---|---|---|---|
| Feet | Meters | Inches | Millimeters |
| 75 | 23 | 1.5 | 38 |
| 150 | 46 | 2.5 | 64 |
| 250 | 76 | 3.5 | 89 |
| 300 | 91 | 4.0 | 102 |
(c)
The exhalation resistance shall not exceed 25 mm. (1 inch) of water-column height at a flow rate of 85 liters (3 cubic feet) per minute when the blower is not operating or under any practical condition of blower operation.