Pond Boss Forums AERATION Systems questions Gast Air filter

Just got a new gast 0523 for my DIY aeration system and was surprised that it only came with a muffler and no air intake filter. Seems like a small engine air filter could be built with a little creativity. Anybody have any insight on where to start or what to source parts from?

Did you check the packaging or do you see anywhere where it shows what all is included in the box? I pulled up your system on a few different websites and all of them say that its supposed to come with a muffler and a filter.

Those sintered filters that come with the compressors won't help much. They will get clogged quickly. You need to rig up a filter, something from a small engine. IIRC Bill Cody has some that he had a guy make the pieces/parts that uses an air filter from a Tecumseh Motor.

Those sintered filters are not supposed to be used for filters and are actually mufflers when the compressor is used for vacuum. You can build your own good filter by using a small engine filter sandwiched between a top and bottom plate.

The filter I used was from McMaster Carr...part number 4369K31. I tested the amp draw with and without the filter and it was 0.1 to 0.2 amps higher with the filter in place. That seemed reasonable to me so I accepted it as "Good Enough". It's been in service for about 4 years now on my Gast 0523.

Here's the link...

https://www.mcmaster.com/catalog/127/428

I chose this filter because it was the same pipe size that the pump offers at the connection. McMaster has higher CFM rated filters, but you have to bell up to 1/2" pipe size and that seemed unreasonable.

BTW, the filter comes with an element included so don't buy two replacement elements thinking you'll use one and set one back as a spare.

Thanks for the ideas guys. I think I came up with a clever solution similar to the ideas mentioned so thought I'd share. I bought a simple npt barbed fitting and a crankcase breather filter that should clamp right on there.

https://www.amazon.com/gp/product/B07T2Q978L/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

That approach will improve the filtration compared to nothing, but you need to be concerned with what size dust particles it will filter out and how much air it can pass. That crank case vent ad does not specify what size dust it will filter out. I'm not saying that it will not filter out the adequate size, I'm just saying you don' know. The McMaster-Carr filter claims it will filter out anything bigger than 10 microns...that's 0.0004 inches and larger...that's very small. The next thing is how much air it can pass. The McMaster filter spec is 10 CFM at 100 psi where the vent has no spec. Once again, the vent may be fine, but you don't know. I was unsure of how much air the McMC filter would pass at our low pressures (5-20 psi) so I bought it and did an amp draw test with, and without, the McMC filter and found it to be minimal and I accepted it. Ideally, the filter should be large enough to easily pass air without any noticeable amp draw increase.

The most important unknown is the particle size that the vent will filter out. The air flow can be determined adequate with an amp meter test, but you can not easily determine the micron rating. The smaller the micron rating, the bigger the filter will need to be to pass more air volume.

It looks like those crankcase filters will work okay and they are reasonably priced. QtrAcre says it is important to filter out the small particulates because in the pump air housing more "dirt" prematurely wears out the vanes. Also blow into the filter to make sure there is very little resistance to air flow in and out. Then knowing this as a new filter it is a good way to check how much clogging there is on the filter. As long as there is good free air movement through the filter it should be okay to continue using it.

I bought a box of 12x12x1 HEPA filters. They look like a miniature furnace filter. I take them apart, fold the filter material just right, and zip tie it to the hose barb on the pump inlet. Works great and it's cheap. One piece of material lasts the whole season.

This is what I put on my 1/4 hp rocking piston, the filter it came with sits on top.

So far so good on the crankcase air filter. It seems more than adequate for the 4 CFMs that I'm pumping through there. Quarter Acre brings up a good point about what size the filters are. I did a little research on oil droplet particles that the filters are intended to filter and found they range in size from 3 microns down to 0.2 microns. I know that's not necessarily what these cheap amazon filters are but I would think it'd be a similar sub 10 micron size like the McMaster-Carr filters.

Nice to here some research has firmed up your confidence level! I know some of the old vent filters where just a can of loose steel wool and that was just to keep the bugs out..lol.