A respirator is designed to provide respiratory protection to the user. The has a form-fitting seal around the user’s face so that any air—inhaled or exhaled—is passed through the filter. Since this is such an essential element of the respitator’s performance, a seal check is required every time a respirator is worn to ensure there are no leaks and the respirator can be effective. 


The Canadian Centre for Occupational Health & Safety (CCOHS) and the American National Institute for Occupational Safety and Health (NIOSH) also mandate that a seal check is required by 29 CFR 1910.134(g)(1)(iii), “For all tight-fitting respirators, the employer shall ensure that employees perform a user seal check each time they put on the respirator.


How does a seal check work?

Seal check


A seal check is a quick (and essential) protocol performed by the user each time the respirator is worn to ensure that the respirator is sealing correctly. 


The user’s seal check can be performed either with positive (exhalation) or negative (inhalation) pressure. Both are considered effective as long as the user follows the respirator’s user instructions. 



Positive pressure seal check

During a positive pressure user seal check, the user exhales slowly while covering the respirator filter with their hand(s), blocking the air path. The test is considered successful if the respirator budges slightly from the pressure before increased pressure causes outward leakage.


Negative pressure seal check

During a negative pressure user seal check, the user inhales while covering the respirator with their hand(s). The test is successful when the device collapses slightly inward under this negative pressure.


Are respirator fit tests and seal checks the same?


No, a user seal check is different from a fit test. The seal check must be performed each time the respirator is put on. A fit test must be performed once a year and help you to determine what model size is right for you. Note that “A user should only wear respirator models with which they have achieved a successful fit test within the last year.” Says NIOSH. 


What is the difference between a seal check vs. a fit test?

A seal check is a simple test to confirm that there is a seal formed between the user’s face and respirator. Done by covering the respirator with hand and breathing in or out to check for leaks. Fit tests are performed to confirm the user’s correct respirator size/model, and are done at least once per year. Fit tests can be quantitative. Fit tests typically take 10-20 minutes test the effective filtration and fit as the user performs different exercises (taking, moving their head around, bending over etc). This is performed by a fit tester with a fit test hood (qualitative) or quantitative device like a portacount. 


Now you know how to perform a seal check, it’s time to put on your Dorma 99 and use your knowledge. Follow the guidelines below and see the User Instructions for how to properly use and care for your Dorma 99 respirator.


Before performing a seal check, To do so, cup the respirator in your hand with the nosepiece at your fingertips, allowing the head strap to hang freely below your hand (Fig. 7). With the nosepiece up, place the respirator over your nose and mouth. Make sure that the respirator rests on the nose. The bottom part of the respirator should be placed between the lower lip and under the chin, depending on the length of your face. Pull the top strap over your head, resting it high at the top of the back of your head (Fig. 8). Then adjust the strap length through the eyelets so that the respirator comfortably covers both your mouth and nose (Fig. 9). Fasten the clips behind your neck (Fig. 10) and pull the loose strap ends to tighten to an appropriate tension (Fig. 11). Make sure to place the respirator correctly and comfortably, and then perform a user seal check.

Seal check


Perform a seal check by using one or both hands to completely cover the respirator filter (Fig. 12), and exhale. The respirator should budge slightly. If air leaks at the respirator edges, reposition the respirator on face (Fig. 13) and/or readjust tension of head strap to eliminate the leakage. Once the seal check is successful, the respirator is ready for use (Fig. 14).


 For further details, read the Donning Instructions section (User Instructions).

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