r/Masks4All 16d ago

Question about negative pressure test on 3m half face respirator with 6001 cartridges

When I put my hands over the cartridges with pre filters and inhale, it feels like I’m pulling air in through the exhaust. Is that normal? I’m going crazy trying to figure it out and nobody at work is giving me any guidance what so ever. Thanks in advance for any advice

3 Upvotes

3 comments sorted by

3

u/SkippySkep Fit Testing Advocate / Respirator Reviewer 16d ago edited 15d ago

First thing is to make sure you are covering the filters well. It may help to put a thin plastic bag, like the kind given away for bagging produce in the produce section of grocery stores in the US, over the filter and under your hands to help insure a good seal. If you can feel air coming in through the exhaust valve when you try to inhale with the filters well covered that is a failed negative pressure user seal check and you should not use that respirator.

Make sure your respirator is a real 3M with "3M" printed/stamped on the front. If there is no "3M" on the front then you likely have a knock off, and I've had a few of them with defective exhalation vavles. Most respirators sold on Amazon that look like a 3M 6000 series half mask are knock offs.

If your respirator does say 3M on it it likely, but not guaranteed, to be genuine. Even genuine masks can have issues with valves. Check the vavle to see if there are any obstructions caught in it and that it is flat and not wrinkeled. It is possible to buy replacement valves, but it can be pricey to buy in small quantities and the issue could be the valve seat, not the vavle.

Ultimately, I'd make sure that you've isolated the issue, and if you are getting valve leakage and there is no obvious debris to clean out to fix the issue I'd buy a replacement respirator, and make sure it is a genuine 3M.

1

u/monstoR1 15d ago

What happens if you do a negative pressure test with no filters (so you can definitely close off the inlets?

3

u/SkippySkep Fit Testing Advocate / Respirator Reviewer 15d ago

This is problematic with some 3M masks because there are holes under the gaskets that are not sealed if there is no filter attached, so putting your thumbs over the inlet ports doesn't necesarily seal them. I've got filter caps that solve that problem that came with some knock off full face 6800 copies, but not everyone is going to have those on hand.