Thread Number: 17470
Carbon/exhaust filters
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Post# 188258   7/4/2012 at 10:44 (2,828 days old) by fan-of-fans (USA)        

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I notice on a lot of more recent machines from the last 20 years or so, the carbon filter on the exhaust. However on vacuums from the 80s or so and before, there was no such filter present. Why was the carbon filter introduced and is it meant to be an extra layer of filtration as well? I know some canister vacuums advertised triple filtration meaning bag, premotor and post motor filters. On my 80s Eureka Mighty Mite, there is a very thin piece of foam inside the exhaust door. Not really sure what it is for as it seems to have never been dirty.

I don't really care for a post motor filter that I can't access without taking apart the vacuum. I took apart my 1999 Kenmore canister and the foam filter on the exhaust was full of fine dust and carbon dust. There seemed to be a big improvement in airflow after washing it, but seems odd to have a filter that is not user cleanable/replaceable. With more recent HEPA canisters and uprights, it seems all filters are user serviceable.

Post# 188263 , Reply# 1   7/4/2012 at 11:18 (2,828 days old) by eurekastar (Amarillo, Texas)        

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I think the carbon filter is designed to filter out odors that are emitted from the bag. 

Post# 188266 , Reply# 2   7/4/2012 at 11:58 (2,828 days old) by kirbykid63 (Wilmington Delaware)        
kenmores from around 2000

I think that was one of the worse designs ever,Those filters get clogged and the motor over heats and fails.Thats why I sell so many kenmore canister motors .

Post# 188267 , Reply# 3   7/4/2012 at 12:06 (2,828 days old) by kirbykid63 (Wilmington Delaware)        
it gets worse!!!!

Most of those canister vacuums also have the motors wraped in a thick foam that also gets stuffed with filth.You really have to break those down and clean eveything about once a year.

Post# 188275 , Reply# 4   7/4/2012 at 13:51 (2,828 days old) by sensotronic (Englandshire)        

Are you talking about carbon filters that are designed to absorb odours from the bag or a filter designed to trap the carbon dust that the motor emits?

I think a removable post motor filter is a good idea as it gives an extra layer of filtration and helps prevent carbon dust from entering the room. Most of the cleaners I owned from the 70's onwards did not have a removable exhaust filter, but nearly all of them had a foam diffuser with a very open texture which would have allowed carbon dust from the motor to escape. 80's Hoover canister cleaners in the UK always had a pre motor filter in the dust bag compartment, but I can't recall any of them having a removable filter after the motor.

Post# 188601 , Reply# 5   7/6/2012 at 07:12 (2,827 days old) by sebo_fan (Scotland, UK, member AKA ukvacfan, & Nar2)        
Hoover cylinders with pre-motor filters

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I recall my Telios models had a square pad made up of a black carbon packed material on one side and white on on the other. Eventually black foam was also available - it seemed to catch dust or particles on it that leaked out of the dust bag, or if the dust missed the dust bag in use. The bits were like grass bits, as opposed to carpet fibres, evidently being lighter by nature.


I always assumed the carbon filter is supposed to protect the motor - the Hoover TP2/3 series had double filters slid into the bottom behind the dust bag above the motor, or in most cases, owners just preferred to use one carbon filter.


Same with the Sebo X uprights - the foam filter is a carbon filter designed to catch the carbon off the motor. although in the Sebo's case the motor filter is no where near the bag compared to conventional uprights. 

Post# 188657 , Reply# 6   7/6/2012 at 18:05 (2,826 days old) by fan-of-fans (USA)        

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I was a bit confusing in my post. I meant carbon filter as in a filter to catch carbon dust from the motor. The carbon containing odor filters didn't really catch on until more recently other than some high end machines.

Richard, I agree on the Kenmore foam material being a problem. Mine I took apart is a Whispertone and had a plastic shell around the motor and the exhaust opening in the shell had a thick piece of foam that was very dirty. The later rounded body Whispertones had the motor wrapped in foam as you described and caused it to overheat. Not sure what are in the various Progressive models as far as foam.

It doesn't seem any machines here in the US had post-exhaust filters until the 1980s. Pre-motor protector filters were pretty much from the start with cylinder-style vacuums I guess, at least other than Electrolux.

The front hose Kenmore canisters up through the early '80s didn't seem to have an exhaust filter. The swivel hose 5055 style models from '85 onward had a very open texture foam in the exhaust vent on the back that didn't seem to get clogged. And then the Whispertones had that hidden foam inside that got clogged easily. Perhaps this changed with the Progressives, as they were the first with removable exhaust filter - either foam block or HEPA. My new Progressive I took the HEPA filter off the back to see what was behind it and it's open texture foam. So hopefully there isn't much to get clogged except the HEPA filter.

Post# 188675 , Reply# 7   7/6/2012 at 21:18 (2,826 days old) by williamr1248 (USA)        
carbon/exhaust filters

My parents old Air-Way from about 1950-51 has a cloth/felt bag that has a drawstring to hold it on the bottom of the motor. This was called a sound suppessor and located within the the body of the machine. It was to be either taken off and replaced or washed about every 5 years to keep the machi from leaving dark spots from the exhaust on the carpets when the machine was used in the upright position (which ours always was).
We did not know that the machine could be used in the horizonal position until I saw someone in the vac club use the machine. In reality even the first 55 Sanitizor was designed to be used both ways and the Air-Way instructons books show it used both ways. Of course in the horizonal position the carbon dust is not an issue but you forced to drag it around like an Electrolux.

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