There are two kinds of shop vacs. Wet/Dry(dual tank) and single tank. The dual tank has a separate4 compartment for liquids, which is accessed by switching the hose from the dry side. No special procedure for that type.

If your vac is the single compartment variety, it should have a cage with a ball inside over which the filter is installed.

That ball is there to seal off the compartment when the liquid reaches a predetermined level. To use that type for liquids, simply remove the filter and use. There is really no need for any filter with liquids.

I've had several shop vacs over the years. Some had the filter and the foam covers. Those were actually inefficient and expensive when used in commercial applications(remodeling). Drywall dust will kill a stock shop vac filter very quickly.

Buy an after market or upgrade filter, don't get it wet, clean it periodically and it will last for years.

I have a Shop-Vac (should have capitalized it) 14gal 5.5HP model. It doesn't have a ball inside the cage, but rather a capped cylinder that can slide up and down freely inside the cage. Maybe it floats? The cartridge filter slides over that cage, and press-seals around it.

So ... if I want to vacuum liquid, can I just remove the cartridge filter (which is permeable paper reinforced with metal screen)? That is, is the purpose of the filter to keep debris out of the motor, and if one isn't sucking debris, one doesn't need it there? And as long as the liquid level doesn't get close to the motor, everything is fine? That's what I'm hearing you say.

"Am I supposed to remove that cartridge filter entirely to suck water?"

Yes.

"What does the sleeve do?"

The sleeve "generally" acts as an additional filtering step in an effort to address particulates that pass thru the initial filter.

"What is the difference between a "reusable dry filter" and the cartridge filter?"

A third step in the filtration process and in "general" for fine particulates, IE dust.

"The manual tells me to put said "reusable dry filter" over the foam sleeve, which I guess is over the cartridge filter. Three filters???"

Correct.

"So ... if I want to vacuum liquid, can I just remove the cartridge filter (which is permeable paper reinforced with metal screen)?"

Correct.

"That is, is the purpose of the filter to keep debris out of the motor."

No! It's to keep you from recycling particulate debris back into the atmosphere. You should or may have the option to vacume and/or blower, or arrows, or some other method indicating an action.

Thank you both. Very helpful. Now why couldn't the Shop-Vac manual say this stuff??

I'm still a little puzzled that the Shop-Vac manual seems to recommend using the foam sleeve if vacuuming liquid. As in ...

"Wet pick up requires the foam sleeve (not standard with all models) or cartridge filter (not standard with all models) to be in position over the lid cage."

... though in other places it suggests, as you say, that the cartridge filter can be removed entirely for wet pickup. If the purpose of the sleeve is to add extra filtering, why would that be necessary with wet pickup? Seems that in wet pickup, most particulates would end up drowned in the liquid.

I have an older Shop Vac brand vacuum and turning it from dry to wet just requires replacing the pleated filter with a foam filter. The foam filter just slides over the plastic "cage".

Ah, really? That makes more sense -- pulling the foam filter just over the plastic cage. See, the foam filter won't fall apart when it gets wet, as the pleated paper filter will, and I guess in the absence of the cartridge filter, the foam filter catches the debris that the water doesn't drown.

In fact, that's right. The quote I gave from the manual says to put the foam sleeve over the lid cage. NOT over the cartridge filter. But it does say that either the sleeve or the cartridge filter needs to be over the lid cage.

But it still seems to me that the easiest solution is just to have a bare plastic lid cage. No foam, no filter. According to snoonyb, that works.

There are filters available that will withstand use in wet applications and avoid blowing mist all over the place.

The Clean Stream Teflon coated ones do very well.

in dry use they can be washed out a number of times and reused.

I actually have two for every shop vac so when one clogs I can wash it and use the second till the first is dry.

Just be careful what dry items you vacuum up with or onto a wet filter.

One of my slower guys managed to pick up setting type joint compound after clearing come traps.

One Durabond coated filter resulted.

I have sucked up liquids I would prefer not to atomize and breath. Like clearing out traps.

This post was edited by brickeyee on Sun, Mar 31, 13 at 17:08

I would surmise that the intend of the foam filter, is in fact, not filtration but as Brickeye suggests reducing the risk of moisture vapor overcoming the seal or being exhausted.

That Cleanstream filter is pretty slick. Teflon coated, eh? It looks like pleated paper, but I gather it is something more solid. Teflon coated paper? Kinda pricey, but with a 1-year satisfaction guarantee.

And yes, the foam filter must be to prevent exhaust of vapor from the vacuumed liquid. But if I'm just sucking fairly clean water, I don't really care too much about that.

Thin enough Teflon for a filter is not very strong.

It needs a backing to give it at least some strength to hold its shape.

I've used the CleanStream filters since they first came out (or close to it). They're worth every penny.

I have a wet/dry Shop Vac QPL 60 that Shop Vac, free of charge, replaced the whole top assembly for free. The replacement sent me in 2009, a lightly used vac, worked well until a few days ago. When I plugged it in to vacuum my car, the motor made a shrill whine noise and no suction. I checked the filter and it is almost like new. I checked the hose and there were no leaks. I even taped all the connections to and from the hose to the tank, but to no avail. Could you suggest what the problem is and if possible, a cure for the problem or must I spend some 82 dollars for a new unit?.

hum..
didn't know cleanstream made teflon coated filter..
I know they make Gor-Tex based filters...
I've used in several shop vac..even use one as a central house vac going on 20+years..

I've the cleanstream filters while sucking up water..instead of removing the paper filter(which should be done, the foam can stay).

so.
if you have a fine paper type filter..remove it for water. leave the foam filter..helps keep larger chunks from the motor/blower
using a CleanStream/Gor-Tex filter..leave it..

-dkenny

If I had to vacuum water with debris in it, like wet sawdust let's say, I think the foam sleeve would be just the ticket.
Casey

To save your paper filter and possibly never buy another one, get a Filterpal. It's a cloth sleeve that you put over your paper filter and the filter will stay clean. You can wash and dry it too. I spent a fortune on filters before learning about this!

Or use pantyhose. Cheap to free and does the much the same thing.

I've used the same filter on my old shop vac for decades now, just took it outside and blew it out when the flow rate dropped. Now I've upgraded to a HEPA filtered vac, at least for sanding and such. the primary filters seem to block all the bigger material from getting to the HEPA filter. It's still working well a year in-- I'd hate to have to replace it too often at $100 a pop. I't nice to not have the haze in the air (and my lungs) after a sanding session.

using a paper filter when sucking water or liquid will ruin the filter. HEPA filters are nice. They work the motor more becasue of the fine mesh of the filter but the "exhaust" is certianly much cleaner

That's so wrong. Just wrong. LOL

klem-

But how do they look with your high heels?

I just went to suck out ashes from fireplace with craftsman 6 gal wet dry vac. within a minute I had dust everywhere....everywhere. I have laminate floors and as I type this I am looking at the dust all over them and its everywhere. the vac hadn't been used in years and I thought maybe its full so I went to empty it in compost pile and there was no filter in it. that's why I'm here. no filter..no filter plate or nut as they are called. I am thinking this may not have happened had there been a filter in the vacuum. I ordered new parts from sears. either way with filter or not..i am going to kill my millennial son ...soon. thank you all for listening. (this comment intended for laughs only I will not actually kill my son.....well..not today anyway.) thoughts and prayers

Unfortunately, without a filter, the vac was just a means of removing a concentrated pile of ashes and uniformly distributing them all over the place. You could have achieved almost the same effect by picking up handfuls of ashes and flinging them around, although it would not have been as efficient. I'm curious about why your son is the culprit, although with children of my own I can make some guesses... ;-)

Wow sorry that happened! Can't help chuckling at the image of a cloud of ashes jetting out of the exhaust port.

FYI, you can get filters for most vacs at hardware stores in case you don't have a Sears close by or the price is not to your liking.

Note to self, check that the filter is in place before cranking up the vac. :-]

Regarding all the discussion earlier in the thread about outer sleeves: they not only prevent lots of water from getting into the paper filter, but they act as a prefilter for coarse particles.

Looks like no one responded to deke4 back in 2014 about the vac that ran but didn't suck. In case anyone else has this problem: I'd be checking in the inlet and outlet (with it unplugged) as far as you can see in to make sure it's not clogged. Failing that, the linkage between motor shaft and impeller may be shot, but you'd have to take some screws out of the motor assembly to see that. Another thing to check is if it has one of those float balls discussed earlier, possibly under the filter, if it's stuck in the "full" position it may shut off the vacuum without shutting off the motor. Pull off the filter and make sure that thing moves freely if your unit has one.

As an outdoor tool, for vacuuming up leaves and yard debris, no filter is needed. Period. Same with sucking up liquid. But for stuff that won't settle out quickly in the can, like ash, sure, a filter would be essential.

this was very helpful. I agree, the shop vac manual is not very clear on the wet pickup issue.

do you need filter when vacuuming leaves in the rain gutter.

if/when you're vacuuming dry material it's always prudent to use a filter. A wet filter doesn't allow sufficient airflow, so if there's water present you get better suction without it.