How long can you use a twin set of P100 filters on a half mask?

My job requires I use a P100 mask (99.97% resistant + resistant to oil). The mask has two filters on it. I'm curious how long (hours) I can use it before I should replace it.





A few people have told me that when it becomes 'a little more difficult to pull air through them'. Another said 'R100 masks can be used for 10 hours, P100 (added oil protection) should last for 20.'





Anyone know?How long can you use a twin set of P100 filters on a half mask?
There should be recommendations on the packaging for the filters themselves, but it really depends on how often the mask is used, and how much exposure you're covering. Obviously lower exposure and infrequent use will extend the life of the filters. Changing them when they get clogged means that you're already inhaling particulates, which defeats the purpose of the mask.

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