Level A fully encapsulating chemical protective suits are tested using a positive pressure test, formally called the Totally-Encapsulating Chemical Protective (TECP) Suit Pressure Test. This inflation-based method checks whether the suit is gas-tight by pumping it full of air and watching for pressure loss over a three-minute window. If the suit leaks too much air, it fails and gets pulled from service.
How the Pressure Test Works
The test follows a straightforward sequence laid out in OSHA’s Appendix A to ยง1910.120. First, the suit gets a thorough visual inspection for obvious damage like tears, cracked seams, or deteriorated material. Any exhalation valves are sealed off so the suit becomes a closed system. A test apparatus is then connected to inflate the suit.
The suit is first inflated to what’s called the pre-test expansion pressure. This higher initial pressure serves a practical purpose: it pushes out wrinkles and creases in the suit material that could give a false reading. Once the suit is fully expanded and smooth, the pressure is lowered to the actual test pressure, and the clock starts. The suit must hold that pressure for three minutes while a technician monitors the gauge.
Pass and Fail Criteria
OSHA sets two key pressure values that suit manufacturers must specify. The pre-test expansion pressure (used to smooth the suit out) must be at least three inches of water gauge. The actual test pressure must be at least two inches of water gauge. Manufacturers can set higher values, but these are the minimums.
The pass/fail threshold is simple: the suit’s ending pressure after the three-minute test period must be at least 80 percent of the starting test pressure. Put another way, if the pressure drops more than 20 percent during those three minutes, the suit fails. A suit that fails gets removed from service immediately. It can be retested, but only after a leak has been located and repaired.
Every test gets documented. The actual values for the expansion pressure, test pressure, and ending pressure are all recorded along with the specific times they were observed.
Finding the Leak
The pressure test tells you whether a suit leaks, but not where. When a suit fails, technicians typically follow up with a leak detection test. This usually involves inflating the suit again and applying a soap solution to seams, zippers, glove interfaces, visor bonds, and valve connections. Bubbles pinpoint the exact location of the breach. Once the leak is repaired, the full pressure test is repeated to confirm the fix holds.
Standards Behind the Test
OSHA’s regulation provides the core procedure, but it doesn’t exist in isolation. ASTM Standard Practice F1052 offers a complementary procedure for pressure testing gas-tight suits and is widely referenced alongside OSHA’s method. The NFPA 1991 standard governs the broader certification of vapor-protective ensembles, covering design, performance, and testing requirements for suits used during hazardous materials emergencies, including protection from chemical, biological, radiological, and nuclear (CBRN) threats.
These standards overlap in purpose but serve different roles. OSHA’s test is a field-level integrity check performed throughout a suit’s service life. NFPA 1991 certification is what manufacturers must meet before a suit ever reaches the end user. Together, they create two layers of quality assurance: one at the factory, one in the field.
When and How Often to Test
Level A suits should be pressure tested before first use, after any use in the field, after any repair or modification, and at regular intervals during storage. The logic is straightforward: chemical exposure, physical stress, and even prolonged storage can degrade seams, zippers, and suit material. A suit that passed six months ago may not pass today.
Visual inspection should happen every time a suit is handled. Look for discoloration, swelling, stiffness, or softening of the suit material, all of which can signal chemical degradation. Check zippers for smooth operation and examine glove and boot attachments for separation. These visual checks won’t replace the pressure test, but they catch problems that the pressure test alone might miss, like material that’s structurally weakened but hasn’t yet developed a hole.