HEPA Filter

[Greg M]

Did a search and found nothing which is unusual because I can almost always get an answer using the search function.

The HEPA filters, how long do they last while still being effective? 

My understanding of filters is that once they get some dirt in them they become more effective.  Most people change their filters LONG before they need changing.  Filters can also be cleaned and reused many times as long as you're careful to not damage them.

When I worked maintenance in class A high rise office buildings in Atlanta we would change the filters about every 3 months or when they "looked" dirty.  Then we put magnehelic gauges on the filter banks and used that to tell us when to change the filters.  We went almost a year (if I remember correctly) before changing them and they were almost black by then.

So, if we use unmodified bags (not cut - I empty mine but don't cut them) how long should the HEPA filters last?  I'm thinking that if the larger particles are kept out of them then they should last many years, even longer with careful cleaning.

Any thoughts?

 

[Administrator_JSVN]

Here is an FAQ that was written for RRP, but it also could be applied to general use.

This is highly subjective depending on degree of use, including frequency, duration, and conditions. Foremost, we strongly urge the use of pre-filter bags which filter dust down to 5 microns, helping to prevent loading of the main HEPA filter, and protect the filter from damage from larger particles of dust and debris. The RRP rules do not provide guidance on this matter, and each different manufacturer may have their own stated guidelines or recommendations. Though it is not possible to apply a hard and fast rule across the spectrum of users or applications, we can provide these basic guidelines:

-The HEPA filter should be visually inspected at every single bag change.
-With every other bag change the filter should be removed and the seal (including the filter and the area on which it mounts) should be inspected for debris that could compromise the seal. Carefully remove any debris with a light, clean, non-abrasive cloth with minimum pressure.
-NEVER use compressed air to 'clean' the filters as it may compromise the efficacy of the filter and the rated filtration.
-In case of any damage to the filter, replace it at once.
-Depending on the degree of use, a filter may need to be replaced every month or any other interval up to 6 months. Filters should be replaced every 6 months to maintain the rated performance.
-Avoid direct contact with the filter element (white cloth-like material).
-Replace filter immediately if it comes into contact with any sharp object or other harsh debris.
-One way to ensure the integrity of your CT Dust Extractor for use in RRP-related applications, as well as to help prevent cross-contamination of lead dust and debris would be to designate a CT Dust Extractor, dedicated solely for the purpose of working in lead-based paint applications. A secondary CT Dust Extractor could be designated for non-lead-based work.
-Replace filter immediately if used without a pre-filter or if the HEPA filter is left in place during a wet extraction operation.
-If you have any question or doubt as to the integrity of the HEPA filter, it is recommended that it is replaced at once.

 

[Greg M]

Shane, thank you for the official government mandated Festool response.  The lead paint over reaction mandates strict rigid procedures that must be followed or risk heavy fines by a bloated out of touch government.  I understand that you are restricted on what you can and can not say on this subject.  I appreciate reading Festool's official response.

Now putting the lead subject aside, I'm concerned about the fine wood dust that I purchased these CT's to protect me from.  I've been told by people in the business that we can carefully use compressed air to clean these (although I understand the risk of damage to the filter) and that the filters can withstand multiple cleanings without loosing effectiveness.

I'm interested in hearing what others do and what you've learned. 

BTW, I'm thinking about getting a particle meter so that I can monitor the effectiveness of my filters over time.  I want to keep my shop air fairly clean.

 

[Coen]

Every six months  [eek]

I guess not a single hobbyist does that. But then again hobbyist aren't fined for it either.