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Air Filters

Looking to buy a particulate air filter and unsure what the port sizing difference makes?

I have the rapidair 3/4 inch line and see that there's quite a price difference in filters with 3/4 inch npt ports to those (even same brand) with, say 3/8 or 1/4 inch npt ports.

Wondering if the bigger port is necessary and/or justifies the additional cost. Definitely not looking to spend money just to spend money.

Oh yea, if it matters, in my case, I have an 80 gallon 2 stage compressor pushing 17 cfm.

Appreciate the advice!

Comments

  • winterwinter Posts: 18Member
    Looking at the Devilbiss QC3 but with a 1/2 NPT inlet and a 1/4 NPT outlet, and together with it being mounted upstream before the shop piping, will that hurt the flow rate considering 3/4 inch piping enough to make a considerable difference? Also, is the 0.01-micron rating ok?

    At right around $200, it seems hard to beat, considering it also includes a regulator, but ????
  • DeviousDipsDeviousDips Posts: 1,215Member ✭✭✭✭
    @winter that's what I have and I run the rapid air as well. I have the QC3 at every drop. I also run a devilbiss snake off of my compressor. 
  • MidOhioHydrographicsMidOhioHydrographics Posts: 8,784Member, Moderator, Business Ninja El Moderator
    edited November 2017
    Yeah stop thinking “whole system” and put filters at the drops. Use a zig-zag manifold w 50’ of copper to cool the air first, then run your loop. Put a filter system like the QC3 before your gun. I like the CT30 personally, but it’s more $$$. I like to use a coalescing filter first as a coarse filter then a Motor Guard filter, then regulator, then to the gun.
    Post edited by MidOhioHydrographics on
  • winterwinter Posts: 18Member
    So .... not sure I follow, but first, thanks, and now the follow-up ... besides the question regarding filter sizing and if makes a noticeable difference, I always THOUGHT the filter(s) are supposed to be placed BEFORE the main line begins to filter out any "trash" (oils, particles, etc.), otherwise the main line and drops can contain that crap.

    Seems like maybe you might want a filter at the beginning and another filter(s) at each drop now? And now we get back to sizing those suckers again. O crap, the expense just exploded again ... and again .... and again ...
  • K2ConceptsK2Concepts Posts: 12,553Administrator El Jefe
    First off? Your air can never be too dry or too clean...

    Secondly? "Air don't care"...Your air in that line doesn't give a rat's behind whether you have a garage business or it's a hobby or you want to go full blown production...the only person that cares about that is you...your air is only as clean as you make it...thus the filtration comes into play...There is no "spend money just to spend money"...you either get on board or suffer the consequences...most of us have thousands of dollars in air filtration and we didn't do it because we just had it laying around or we want to brag about how much we spent on an air delivery system...

    So yea you should have a filter right after the compressor...usually a coalescing filter or similar...then a refrigerated dryer...and then filters at every drop...just the way a proper air system is constructed...and again it has nothing to do with your budget...it has everything to do with a properly constructed clean and dry air system...Here is a picture of a properly designed air system...




    All that mumbo jumbo being said? 17 CFM requires 3/4" pipeing all the way up to 300 feet in length...so if you are going to get a "inline" filter? It will have to be a minimum of 3/4" ID. Now at your drops? That is based on the air you will consume at that point...which is why you see a decrease in sizing...usually 1/2" or 5/8"...below is a chart of the required pipe sizing...




    So the matter is physics...and there is a reason they call it a "Law"...because if you break it? You pay the penalty in other areas such as trash in your clear coat or fish eye in the case of particulates...clear coat "die back" is almost always moisture related in my opinion so that can happen as well...

    The biggest mistakes people make when designing air systems is that they undersize the lines or fittings and they never plan for the future...then they hamstring themselves by going cheap which just compounds the problems...

  • smedlinsmedlin Posts: 1,232Member, Business Ninja ✭✭✭✭
    Why the air filter right before the refrigerator? I didn't do that.

    I went straight from compressor to an Ingresoll Rand fridge to a Devilbiss Stage 5

    Did I screw something up?
  • winterwinter Posts: 18Member
    Jim, surely appreciate the charts and edumacation! Sure helps. I do indeed have the 3/4" RapidAir piping like @DeviousDips mentioned, but if I understand what Jim says about having to go with a 3/4" inline filter(s) off the main line, then either the QC3 or CT30 is not really the best option here due to their smaller port sizing. Right? Any suggestions on which 3/4 works best?

    Now at the drops either of those seem to be ok, it's just a question of pennies. Guess either will supply sufficient flow for the blast cabinet?
  • K2ConceptsK2Concepts Posts: 12,553Administrator El Jefe
    smedlin said:

    Why the air filter right before the refrigerator? I didn't do that.

    I went straight from compressor to an Ingresoll Rand fridge to a Devilbiss Stage 5

    Did I screw something up?

    Any oils or particulates that get sucking into the compressor go right into your refrigerated line dryer...so you try to catch it before then...most filters a dual capacity filter AND oil coalescer so you put them before your refer unit...least that's what we did...



    The stage 5 is a different type of filter and belongs at the drop to the gun so you are fine there...but if you run into oil or water issues? You might want to add a filter for the main line...

    It all works together...but that's why I put that diagram into your training booklet...or did you skip that part?...
  • K2ConceptsK2Concepts Posts: 12,553Administrator El Jefe
    winter said:

    Jim, surely appreciate the charts and edumacation! Sure helps. I do indeed have the 3/4" RapidAir piping like @DeviousDips mentioned, but if I understand what Jim says about having to go with a 3/4" inline filter(s) off the main line, then either the QC3 or CT30 is not really the best option here due to their smaller port sizing. Right? Any suggestions on which 3/4 works best?

    Now at the drops either of those seem to be ok, it's just a question of pennies. Guess either will supply sufficient flow for the blast cabinet?

    Well you have to factor in the blast cabinet...if you buy one that consumes 20 cfm? Well you are already screwed at the compressor...so get the blast cabinet requirements in mind before you start the piping...

    As for a proper filter for the MAIN line? I used a Atlas Copco PD50+, Inline Coalescing Filters, High Efficiency, 120 cfm, 3/4" NPT...way overkill but my compressor can put out 50cfm at 150PSI if it has to...my line dryer puts out 80 cfm so my filter is over both those capacities...

    Compressor 50cfm
    Refer Unit 80cfm
    Filter 120cfm

    See where I am going with this?...



    Bottom line is that we will not have any capacity issues even if we upgrade to a blast cabinet or even a larger compressor (within reason)...mainly because we planned for the future as best we could...no kill like overkill...
  • WileECoyoteWileECoyote Posts: 5,733Member, Moderator, Business Ninja El Moderator
    Unless the device specifically needs oil (to be lubricated) I would NEVER run unfiltered air into it. And if it DID, I would STILL filter it, and then add a lubricator. So... Always filter all your air... Unless you just want to burn up your tools.
  • smedlinsmedlin Posts: 1,232Member, Business Ninja ✭✭✭✭
    BTW, for those who live in humid areas (I'm on the Gulf of Mexico).. I consider a fridge unit a must have.

    The ONLY time I have ever had water in my drop down drains or my stage 5, is when somebody (Randi) forgot to turn the fridge on, and ran the blaster for awhile...

    I can run that compressor all day long, check all the drains/filters next morning, and not have a drop show up.

    They ain't cheap, but sure are worth it.
  • K2ConceptsK2Concepts Posts: 12,553Administrator El Jefe
    Yes...that is the general understanding...there ain't nothing you can do about it so just install one when you live in that kind of environment...
  • MidOhioHydrographicsMidOhioHydrographics Posts: 8,784Member, Moderator, Business Ninja El Moderator
  • K2ConceptsK2Concepts Posts: 12,553Administrator El Jefe
    I have heard it was actually a decent product...almost got one myself but I would need one for every drop in the shop sooo...just got a big one instead...
  • smedlinsmedlin Posts: 1,232Member, Business Ninja ✭✭✭✭
    I had actually ordered that one from HF.. then found out it was back-ordered. Like 2 months.

    So I canceled the order (or so i thought) and ordered an IR one. Was more than twice as much..

    Then like 3 months later, the HF one showed up at my door. I checked and my credit card was run for it.

    So now, the HB one sits in my attic, still in the box.
  • DeviousDipsDeviousDips Posts: 1,215Member ✭✭✭✭
    Thanks for posting that Joe. I've been looking at some and I think I'll try that one out. @smedlin if it's still on back order and u wanna unload yours I'll take it off your hands if i can't get one right away
  • MidOhioHydrographicsMidOhioHydrographics Posts: 8,784Member, Moderator, Business Ninja El Moderator

    I have heard it was actually a decent product...almost got one myself but I would need one for every drop in the shop sooo...just got a big one instead...
    Same here. My Emax dryer handles 100cfm, compressor is 90. I should be good for a long time. Lol! But that combo was not the budget route whatsoever.
  • smedlinsmedlin Posts: 1,232Member, Business Ninja ✭✭✭✭

    Thanks for posting that Joe. I've been looking at some and I think I'll try that one out. @smedlin if it's still on back order and u wanna unload yours I'll take it off your hands if i can't get one right away

    @Gotcha_covered, who lives maybe 15 minutes from me, already said he wants it.


  • winterwinter Posts: 18Member
    Maybe its just me, but confusing to say the least as far as best practices go!

    From what is seems, we all are doing a little something that we THINK works, but who knows if our setup might work better another way?

    First, let me say I definitely understand the point about "your air can never be to dry". Makes total sense.

    Does a water separator with a 5 micron filter perform the same filtering function as a general 5 micron particulate filter, or should they both be installed off the main drop?

    I THINK I see it's best to put another filter downstream at the paint booth, but once again, what type(s) are recommended? (Another water separator, then another particulate filter, or is one available to do both, maybe here down to .1 micron?

    Thanks
  • K2ConceptsK2Concepts Posts: 12,553Administrator El Jefe
    Water separators are only good for drops that supply air to your air powered tools...like sanders and grinders...Particulate filters need to be right before your paint guns...and they are usually a combination separator, coalescing filter and desiccant filter...just for giggles...
  • WileECoyoteWileECoyote Posts: 5,733Member, Moderator, Business Ninja El Moderator
    @winter you only know when your situation doesn't work. There is no limit to the money you can waste on OVERdoing it. The shop I worked for had redundant filtration and dessicant driers. We changed point of use filters after 15 years that still looked brand new... But it was costly.
  • MidOhioHydrographicsMidOhioHydrographics Posts: 8,784Member, Moderator, Business Ninja El Moderator
    Search Amazon for Motor Guard filters. I run them right before every gun. Very fine particulate filters that work fantastic. It's a final stage for us.
  • winterwinter Posts: 18Member
    Thanks to all for the info!
  • smedlinsmedlin Posts: 1,232Member, Business Ninja ✭✭✭✭

    Search Amazon for Motor Guard filters. I run them right before every gun. Very fine particulate filters that work fantastic. It's a final stage for us.

    I run the same thing at each gun.


  • DeviousDipsDeviousDips Posts: 1,215Member ✭✭✭✭
    @MidOhioHydrographics @smedlin can u buy refill for those or do u just change the whole thing once they are done. Like the 
  • MidOhioHydrographicsMidOhioHydrographics Posts: 8,784Member, Moderator, Business Ninja El Moderator
  • DeviousDipsDeviousDips Posts: 1,215Member ✭✭✭✭
    Ok I have 2 of those hooked up. Those are great filters in my opinion. 
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