Thread: Cleaning pleated filters

I have mentioned before that I had dust filters cleaned that I got from work when they threw them away. It was a dry process and cost me $40 Can each at that time. Industrial filters can be cleaned 3 or 4 times at least so adds up to a great saving over replacing with new. The one thing that the gent told me was that the Chinese filters with the paddle cleaner disintegrated with his filter cleaning process. There is a filter cleaning company at Bob's end of the country so you might want to see if there is a similar outfit in yours and get their opinion. I would think that water would likely wreck yours but a dry cleaning process might not.

Pete

Have you tried vacuuming it?

QCInspector, thanks for the info. I'll do some ringing around next week.

extra info a search found that the company that cleans our vehicle DPF,s has been cleaning air filters for 25 years.

Aldav - tried vacuuming as well. In an earlier post I mentioned that when I got this unit I suspected the filter and when I removed it, there was hard set dust in the inside valleys which I removed with blowing and vacuuming. I believe this unit hasn't had the paddle turned as often as it should and is fairly old.

Cheers guys

Rang the company today re cleaning my filter. $50. Can't do it for 1 to 2 weeks as they do them separately to vehicle and equipment air filters.
I'll keep you posted on the results.

I'll be following this with interest. It sounds like your filter is effectively glugged-up with reconstituted MDF, yuk! If they can successfully clean it it would also be interesting to know how they do it. Good luck!

Do they test the filters after they clean them?

I asked the very same question " do you flow test before and after cleaning?" The answer was no, they just inspect them for leaks/holes.
They have however, been doing it for over 25 years and have an impressive list of clientele so I guess my before and after flow tests will indicate if the job has been done. I did indicate I would be carrying out flow tests and it didn't seem to phase them.

This topic is of great interest to me. Amongst numerous dust extractors we have in use for machinery and all with pleated filters, I also have a Nilfisk IVB 'H' class portable vac for our smaller power tools. This was purchased at quite some expense as many suppliers will sell 'high end' portables that only an 'L' class rating.
Previous research shows an 'L' class vac is in fact not suitable for the MDF's and most of the hardwoods. An 'M' class would have been okay for typical timber sanding, but given we sometimes sand back solid timber that has been previously painted/lacquered, I decided to go the extra mile with an 'H'.
Imagine my dismay when on first use the paper bag split and the H filter was then clogged solid. Blowing out with compressed air is not recommended as it can force the particles deeper into the filter and I tried suction with another dust extractor without any real success. The inbuilt alarm on the machine is now a common 'friend' ..These are not washable and a replacement filter was quoted @ around $500.00.

Would be interested to know if there is a reliable company in Australia that services woodworking filters.

Regards-C.R.

I'd never thought of a small cyclone ahead of a vac. as an added level of protection for an expensive filter element, but at that price for a replacement it seems like a small price to pay for a little extra peace of mind.

C.R. I'm curious to know what the vacuum / extractor cost to buy? Can the filter be blown clean from the backside? Any chance of some pictures of the machine and its innards, or at least the model number so I can look it up? I've always wondered how the big ticket vacs compared to the cheapie ones most of us can afford.

Thanks
Pete

The disturbing thing I found when I tested the filtration efficiency of some 2 dozen DCs and VCs was, apart from a couple of brand new units, they all leaked.
The older and more mobile the units were the more they leaked.
Many of these leaks were visible and could have been picked up by a simple visual inspection but many were not visible and could only be detected using a particle detector.

This is where proper filter testing should extend beyond just a simple flow test which just measures blockage, what you also really need to know about is leakage.
Sending a filter off to be tested may not help because most of the leaks I observed were in the seals and junctions of the filter housings
There were also many pin prick holes in filters and plastic collector bags.
These would be too small to register in any flow test - in fact the filter could be blocked elsewhere and its the pinpricks what is letting the air through.

At work the Laboratory HEPA filters were tested by an external testing company once a year for flow, and for leakages using a DOP (dispersed oil particle) test.
These guys were a bit rough and sloppy so we gave them away and did our own tests more regularly, and especially just before any critical experiment, using particle detectors.
Most of the holes we found were in filters located close to where lab staff worked.
If staff even lightly touched a filter we asked them to report it so it could be tested.
Accessible leaks could often be successfully sealed with a dab of silicone.
Inaccessible leaks required the replacement of the complete filter and at $700 - $1000 a pop it was not a cheap exercise.

This sot of testing is painstaking work and I can fully understand why woodworkers would not do this.
The cost in labour relative to the cost of the filter usually doesn't warrant this sort of testing so they should be replaced on a regular basis (se below) - but what if the new one leaks?
I estimated we tested several hundred HEPA filters during my time at work - we did find a new one that leaked (it had a cracked frame - probably from being dropped) and had it replaced.

If you absolutely have to use any sort of a dust filter inside a shed and want some assurance about filter leaks I would recommend regular inspection of the filter (look for a small dark stains they are leaks) and consider replacing it every 5 years or so whether it needs it or not - same as you would for a car air filter
Also I recommend inspecting the filter seals every time the filter is removed and if it is not removed, on some sort of regular basis. The seals and mating surfaces should be wiped clean and rubber seals reconditioned with something like Armourall.
For something like a Vacuum cleaner I would recommend a complete replacement every 5 years or so as by then the motor cooling loops will so contaminated with fine dust they often generate more fine dust than they collect.
I realise that will especially irk pleated filter and Vac owners but that is the reality of the situation.

AND don't reuse the plastic sawdust collector bags - these are the worst.

All this why it is safer to where possible vent a VC or DC outside a work area.
Even in restricted work areas there are ways and means e.g. when I use a shop vac inside the house I attach a hose to the outlet and dangle that out of a window.

The filter cleaning place I took mine to used a 700 watt light in a darkened room, placed inside the filter to look for pinholes etc. Is this sufficient for our purposes? Or will it be more prudent to monitor the particle count with my Dylos after a cleaning?

Pete

Originally Posted by QC Inspector

The filter cleaning place I took mine to used a 700 watt light in a darkened room, placed inside the filter to look for pinholes etc. Is this sufficient for our purposes? Or will it be more prudent to monitor the particle count with my Dylos after a cleaning?

I don't know Pete. Im thinking the light would work for larger holes and smaller ones that were in a direct line from the light to the observer but I'm not sure I how well that would work for a hole that was sideways thought a pleat.
A possible problem with the Dylos is that it may not have the sensitivity to locate a small hole as you moved it past a leak.

You could try placing the Dylos at the centre of some kind of trumpet arrangement that is placed close to the filter and leaving it sampling over a longer period while you make some dust that is collected - that may tell you if certain areas of the filter have a problem.
The Dylos should certainly pick up a leak at the seal and I would use it to check that on a regular basis.

The plan is to put the Dylos by the exhaust of the "bag house" with the cartridges and monitor what is escaping. If the count starts going up then the hunt begins to see if the reason can be found. Seal leaks, tears or holes, a filter coming loose etc. I won't be able to scan around each individual filter once in the "bag house". As always, your opinion respected and appreciated.

Pete