Our recent review of welding RPE has thrown up an interesting conundrum on the maintenance schedule for filters.  Our organisation carries out training and research and uses a range of different manufacturer air fed RPE with short duration use.  We carry out regular recorded maintenance and inspection and change filters after maximum 6 months, if air-filters look clogged if airflow tests are down or if air pump alarms kick in

All manufacturers apart from one have come back with sensible timescales on the requirement to change the filters however one has come back stating the filter requires changing on a monthly basis even if the unit has had limited use.  My original thought was that this may be due to the filters having a chemical inhibitor that may bleed off during the month, when I questioned the manufacturers technical representative, I received the following response;

The one-month maximum use time is a legislated requirement, rather than something laid down by the manufacturer, and does not account for working patterns.  To ensure that you remain compliant the filters would need to be changed once a month at least even though they may have plenty of capacity left in them, based on the use pattern you have described.  This use time is based on the requirement to be able to demonstrate maintenance that kicks in after a month and is a piece of legislation that you cannot comply with when it comes to filters, as there is no maintenance that can be demonstrated.  It is simply down to the fact that you can't demonstrate maintenance that forces you to change the filters regardless of their time in use.

Does anyone else use these monthly timescales for their RPE?

There is an OSHA update stating 40 hours use or 30 days whichever comes first...it is being misinterpreted as the maximum by some US based suppliers...

https://www.osha.gov/SLTC/etools/respiratory/

There is no legal requirement to change filters monthly in UK law, there are requirements for monthly maintenance and inspection but not filter changes.  I would ask them to send you an extract from the regulations that states the requirement that they are claiming.  Sounds like a wizard wheeze for selling more filters to me!