An official website of the United States government
Here's how you know
A .mil website belongs to an official U.S. Department of Defense organization in the United States.
A lock (lock ) or https:// means you’ve safely connected to the .mil website. Share sensitive information only on official, secure websites.

Home : Articles
Would you stake your life, right now, on the condition of your equipment?
NEWS | April 13, 2020

M50/M51 Mask: Remove Filter Patches Turning Blue

You might notice the M61 filter’s time patches turning light blue on your unit’s M50/M51 protective masks. WP 0004-00 in TM 3-4240-542-13&P (May 08) tells you that if the center of the patch turns blue, then the M61 filter is expired and must be replaced.

A white time patch means the filter is serviceable. But any shade of blue means the filter’s expired and needs replacing. So don’t use it in chemical or biological environments, including the CS gas chamber, if the patch is any shade of blue. That’s because the particulate filter may be wet, which won’t protect you from CS gas.
Want to get better search results faster? 
Click the link below to access our "how to" guide
After entering a keyword, you must hit or click the Search bar/box below for the function to work.
Simply hitting Return won't yield results.
Note about links to archive articles

If you come across a link to a pre-2014 PS Magazine issue or article that uses LOGSA in the web address (URL), use this link instead:
For issues/articles from 2014 and after, click on the Archive/Index tab in the top menu of this website.

BE ADVISED: With the migration to Army365, emails in older articles may still reflect an address. To update, change the domain to