Thanks Thanks:  0
Likes Likes:  0
Needs Pictures Needs Pictures:  0
Picture(s) thanks Picture(s) thanks:  0
Page 1 of 3 123 LastLast
Results 1 to 15 of 31
  1. #1
    Join Date
    Oct 2007
    Location
    Sydney
    Posts
    3,112

    Default Quick connect air couplings and air pipe

    I presently use 1/4" quick connect couplers for all my air requirements, but suffer massive pressure drops when I'm using air hungry tools/spraying. I will overhaul the whole system, but included in that is looking at the actual coupler system I'm using. I remember reading an article about quick connect fittings and it showed just how much psi loss is typically associated with each fitting. The article recommended, IIRC, that unless you're changing the connection more than once per day you're better off having a straight threaded connection, otherwise expect little more than a puff out the end ... precisely what I'm getting!

    I think the fittings I'm currently using are technically called 1/4" "industrial interchange", but I would like to find a chart or similar information that compares the various fittings and sizes commonly available in Australia, and shows the flow rate etc associated with each type. I'm thinking of switching to Nitto fittings, but given the expense in changing several dozen fittings it's not something I want to leap into. An alternative may be larger or high flow versions of what I'm currently using.

    The second part of my question is regarding replacement air hoses. I'd like to run permanent plumbing for my air to various points instead of the flexible hose. I'd like something as large as possible to both minimise restrictions and further add to the receiver capacity. I believe the standard now is to run plastic (PE???) pipe, however I'd like to know what others here have used. A supplier in Sydney would be good, otherwise any that show prices online so I can design the system and work out an approximate cost.

    Cheers,

    Pete

  2. #2
    Join Date
    Nov 2007
    Location
    Mt Crosby, Brisbane
    Posts
    177

    Default

    Water plumbing fittings work fine. Most compressed air is only 100 psi or less and reticulated water can get that high easily. Moreover plumbing fittings have to contend with water hammer which is a massive force whereas compressable air is relatively soft.

    So:

    Big bore plastic copper or gal fixed pipes. Garden hose for flexible air lines. Not drainage pipe. Pressure side only.

    The fittings flow rates are mostly dependant on the bore. You can get into turbulent air flows if you want but it's either big maths or experiments and you'll fine the differences are small. The reason you mostly lose in the fittings is the holes here are the smallest orific that the air flows through. Unless your running long lengths of small diameter pipe the main flow restriction is the littlest hole. A given cross section will flow a certain amount then resist heavily, so more pressure doesn't fix the problem, you get into severe diminishing returns. Also circular sections have the smallest circumferential area to cross section so are more efficient than other shapes.

    So big pipes, big fittings, short hoses. Check out reece or tradelink
    I'm just a startled bunny in the headlights of life. L.J. Young.
    We live in a free country. We have freedom of choice. You can choose to agree with me, or you can choose to be wrong. Me.

  3. #3
    Join Date
    Oct 2007
    Location
    Sydney
    Posts
    3,112

    Default

    If you're talking about PVC pipe water pipe it most definitely shouldn't be used for air lines. The pressure isn't the problem, pressure plumbing pipe will easily handle the 100 psi, indeed my mains water is precisely that. The problem however is that it's brittle, and if somebody accidentally hits it with something (not that it's likely in a workshop ) it will shatter and go off like a bomb in the person's face. However maybe you're referring to some other nylon or PE plumbing pipe???

    Pete

    Edit: While having lunch I tried to find some images of what happens when PVC fails while carrying compressed gas. Unfortunately while I could find plenty of stories and lots of warnings, actual images (I do like pictures) weren't so easy to come by. Unfortunately this is all I could find, and need to get back to work, so will just have to leave it to members' imaginations at to what it looks like when the PVC shatters http://orosha.org/pdf/pubs/fact_sheets/fs44.pdf It's a real shame as it's cheap and I'm quite familiar with using it, unlike some of the other types of plastic pipes, which I have never used.

  4. #4
    Join Date
    Jul 2011
    Location
    Melbourne Australia
    Posts
    1,376

    Default

    Pete, Take a look at Calair and Polair. Anything new I see is done in polymer pipe. I swear by it, clean, no leaks, fast to assemble, and looks good.

    http://www.calair.net.au/

    http://www.polair.com.au/technical.html

    I’m quiet convinced the Calair fittings years ago were Philmac compression fittings.

    http://www.philmac.com.au/Product/Product/ProductRange.aspx?r=23

    We had a pool / pump place nearby at the last factory. The fitting’s from them were identical, but half the price.

    Unfortunately while I could find plenty of stories and lots of warnings, actual images (I do like pictures) weren't so easy to come by.
    That’s because that’s taken on a life of its own since the internet. Every one swears they know someone that had a hand blown off by flying shrapnel. I tried finding pictures once. I particularly liked a story about a PVC line erupting and blowing the side of the factory off. I think a few liberties get taken.


    I have a confession. I did the entire first factory in PVC, didn’t know any better pre-internet. Never had a problem with it. I wouldn’t do it now days, I’d go one of the above.

    Phil.

  5. #5
    Join Date
    Oct 2007
    Location
    Sydney
    Posts
    3,112

    Default

    Quote Originally Posted by Machtool View Post
    I particularly liked a story about a PVC line erupting and blowing the side of the factory off. I think a few liberties get taken.[/FONT][/COLOR]
    Ha ha, I haven't heard that one, but I reckon it may be a bit of a stretch. I wonder if the author works for our PR department

    I was just speaking with my neighbour about it and his factory is STILL plumbed with PVC for the air. However there's a lot of good things to come out of the 'net and warnings about unsafe practices are one of them. The temptation is to use it; it's cheap, I know how to plumb with it, and plenty of people have used it previously. But then I wondered how I'd feel if my little girl was down in the workshop, dropped her bike against a pipe, and it went off in her face. The decision is a bit of a no brainer when considered like that!

    Thanks for the tips on the fittings, that's exactly the sort of thing I was after. I knew there are some plumbing pipes and fittings that are also kosher when it comes to compressed gasses, as if they fail they split rather than shatter. The trouble is from what I've seen, go into a compressed air specialist and I'll get to touch my toes. Again!

    Pete

  6. #6
    Join Date
    Oct 2007
    Location
    Sydney
    Posts
    3,112

    Default

    Phil thanks again for those leads, are those fittings you liked to also irrigation fittings? They look very familiar to me!

    This is a publication I've found from PIPA about using PE pipe, and I wondered about using PE100 12.5, that should cover the pressure that I would use and 25 mm x 50m roll of metric blue line is under $55!

    http://pipa.com.au/images/pdf/pop002.pdf

    Dural Irrigation - Pipes & Fittings > Poly Pipe (HDPE, MDPE & LDPE) > Metric Poly (HDPE Blue Line Pipe)

    The fittings are also cheap as chips too.

    I'm going to make a DIY water condensor between the compressor and the receiver (nothing more than a roll of copper tubing, either in a bucket or water, or more likely with a fan under it) with a water trap at the end of it before feeding back into the receiver. I'm not sure how much that will cost me, but if I can use this irrigation pipe etc I reckon I could plumb the place really well with full drops etc etc for well under $150. Bargain! I've used this stuff in smaller diameters a fair while ago, and it's stupidly easy to plumb.

    Pete

  7. #7
    Join Date
    Jul 2010
    Location
    Melbourne
    Posts
    9,088

    Default

    Hi Pete,
    I haven't used those fitting much.
    Just wondering, are you sure you don't have a blockage in the compressor/line somewhere? Flow shouldn't be a problem for spraying, its normally CFM that's the issue. Maybe one of the metal fitting on the receiver has rusted up? I have a 14cfm compressor and use 1/4" Jamec fittings, even through three fittings and a 20m hose real I can still empty the receiver faster than the compressor can fill it. (unless of course you have a huge compressor)

    Nitto may have a bigger Dia, the only issue I have with them is they are much easier to disconnect by accident than the Jamec, though maybe about the same as your current ones?

    Stuart
    Last edited by Stustoys; 30th Mar 2012 at 04:44 PM. Reason: p.s.. then removed ps because it turns out I cant read lol

  8. #8
    Join Date
    Oct 2007
    Location
    Sydney
    Posts
    3,112

    Default

    Hey Stuart, no I don't think there's anything actually "wrong" mechanically with my system as such, it's a pretty much a textbook case of having high pressure to begin with (let's say when I first pull the trigger in something like a HVLP spray gun), then it drops to much less pressure. I tried bypassing the reg etc but I'm pretty certain the problem is that in addition to the 20 m hose I have something like 5 or 6 disconnect fittings and also some pretty wimpy hose between the tank and the hose reel I typically use. I think the thing is simply getting choked off. I wish I could recall the article I read, it wasn't THAT long ago, but my goldfish memory is as reliable as ever, anyway they showed just how much pressure drop to expect through all the fittings. It's quite staggering when they're all added them up.

    Based on what you've said, maybe what I'll do then is put the plumbing in, and see how I go. Assuming I used a full 50 m roll of 25 mm pipe, if I've done my sums right, that's effectively around another 25 litres of receiver capacity too. Better than a poke in the eye when running a relatively small system. My compressor is only 8 cfm and it doesn't keep up with some of my tools. The head pooped itself a while back, so I did the bodgiest repair on it to finish the spray job I was doing at the time, and hoped it would blow up again so I would have a legitimate excuse to upgrade it to a higher capacity head (I'll use the same receiver), but the rotten thing just keeps on truckin'. Where is the Chinese "reliability" when I need it 'eh!

    Assuming I use these pipes and fittings, how's the best way to tap into the drops and provide a fitting suitable for air connection. If it was steel pipe I'd tap it 1/4" BSP, I'm pretty sure I have a tap here. But not sure how to go about this when it's relatively thin walled plastic? Presumably some fitting? T fitting and tap a cap?

    Pete

  9. #9
    BobL is offline Member: Blue and white apron brigade
    Join Date
    Feb 2006
    Location
    Perth
    Posts
    7,183

    Default

    Post 56 in this thread shows how I reticulated air around my shed with Galv pipe and an external compressor housing.

    All I can say is - I love it. I have air pretty well anywhere inside the shed and no tripping up over hoses etc.

  10. #10
    Join Date
    Jul 2011
    Location
    Melbourne Australia
    Posts
    1,376

    Default

    Assuming I use these pipes and fittings, how's the best way to tap into the drops and provide a fitting suitable for air connection. If it was steel pipe I'd tap it 1/4" BSP, I'm pretty sure I have a tap here. But not sure how to go about this when it's relatively thin walled plastic? Presumably some fitting? T fitting and tap a cap?

    You don’t drill and tap that tube Pete.

    That Dural irrigation site are actually selling Philmac fittings.

    Assuming we stick with 25mm tube.

    You run completely around the workshop to make a loop. Higher the better so its up and above any shelves, racks, etc.

    Every where you want a drop, throw in an equal tube – tube – tube tee.

    http://www.philmac.com.au/Product/Product/ProductClass.aspx?c=272

    Then come vertically down the wall to a tube to thread end connector.

    http://www.philmac.com.au/Product/Product/ProductClass.aspx?c=253

    Those ones are 25mm tube to ½ female BSP. If you want smaller outlet install a reduction bush.

    If it was industrial, you would put a tube – thread – tube tee for your take off, and put a dropper below that with an end connector for a drain.

    http://www.philmac.com.au/Product/Product/ProductClass.aspx?c=269

    You can even use those in spots up on your ring main, just plug the outlet, for a down the road spare.

    Here’s the trick, when your fitting off the thread end connectors, especially when using brass or gal fittings. Metal into plastic, you can tighten them until your blue in the face. The tapered thread just keeps expanding the plastic fitting.

    Use loctite, 55 or 567. Teflon tape is near useless. Let the loctite make the seal, and only do the fitting up with moderate torque. Calair sell a thread locking compound, but I think its loctite anyway.

    Phil.

  11. #11
    Join Date
    Oct 2007
    Location
    Sydney
    Posts
    3,112

    Default

    Oh cool, thanks Phil, no I realised I wouldn't be able to tap that tube, maybe that was a bad choice of words on my behalf. I didn't know they already did the BSP adaptors, that was the part I was wondering about. Perfect!

    I'll install a drain at the bottom of each of the drops, no real imposition to do so. I'm not sure if i'll actually be able to plumb it as a true ring, but will see how it all goes.

    The only remaining thing to sort out is what to use as a filter, and possibly secondary water trap. I think if I do that home brew one from the compressor it will get most of it. I was thinking of a motorguard "dunny roll" filter in the main line, but haven't yet decided. I'd be keen to know what others are using in this regard.

    Thanks Bob, yes having convenient air is fantastic. I prefer air tools for most things, however my own compressor isn't really up to pushing the air needed for some of them.

    Cheers,

    Pete

  12. #12
    Join Date
    Jun 2011
    Location
    Australia east coast
    Age
    71
    Posts
    2,713

    Default

    Quote Originally Posted by Pete F View Post
    Oh cool, thanks Phil, no I realised I wouldn't be able to tap that tube, maybe that was a bad choice of words on my behalf. I didn't know they already did the BSP adaptors, that was the part I was wondering about. Perfect!

    I'll install a drain at the bottom of each of the drops, no real imposition to do so. I'm not sure if i'll actually be able to plumb it as a true ring, but will see how it all goes.

    The only remaining thing to sort out is what to use as a filter, and possibly secondary water trap. I think if I do that home brew one from the compressor it will get most of it. I was thinking of a motorguard "dunny roll" filter in the main line, but haven't yet decided. I'd be keen to know what others are using in this regard.

    Thanks Bob, yes having convenient air is fantastic. I prefer air tools for most things, however my own compressor isn't really up to pushing the air needed for some of them.

    Cheers,

    Pete
    Pete, I looked into this recently after doing a lot of spray painting at pretty high pressure (more like spray blasting). Blue line poly pipe is the way to go. If you look at the different grades, you'll see that some are rated at considerably higher pressure than you need. I'm going to run a 32mm or 40mm ring main around my shed, with droppers as required.

    Metric Poly Pipe for Pressure Applications

    I've bought stainless camlock fittings etc off these guys, good service & prices. Buying the pipe you'd be better to buy locally & minimise freight.

    Only real downside using big bore pipe is the cost of the fittings goes up - a lot. OTOH it makes a good air reservoir too.

    PDW

  13. #13
    Join Date
    Oct 2007
    Location
    Sydney
    Posts
    3,112

    Default

    Hey Peter, ok thanks. I was looking at 40 mm, but if this was old school pipe it would be 1" and so I think 25 mm would be reasonable for the type of work I'm likely to do. I'll pop over to Dural when I get a chance and see what they have in stock. Unfortunately I have to jump in the "hydraulic box of doom" in a week for my quarterly reaming, so nothing much will happen until I get back from my next trip. At least I now know what I'm going to do with this and hopefully the installation won't take too long.

    Pete

  14. #14
    Join Date
    Aug 2008
    Location
    near Rockhampton
    Posts
    6,216

    Default

    25mm would be heaps big enough... You could easily go 3/4 or 1/2" or more correctly the metric equivalent, as it is the blue striped poly pipe that is the high pressure pipe...

    Yellow stripe usually indicates poly pipe for gas usage.... no stripe or green stripe is rural poly in imperial sizes...

    The metric fittings are you just loosen the end, press in the pipe and tighten...that is all there is to it...
    Gold, the colour of choice for the discerning person.

  15. #15
    BobL is offline Member: Blue and white apron brigade
    Join Date
    Feb 2006
    Location
    Perth
    Posts
    7,183

    Default

    Quote Originally Posted by Machtool View Post
    That Dural irrigation site are actually selling Philmac fittings.
    Those fittings are really nice to use. We use them for our reverse osmosis (63 mm) and deionized (50 mm) water loops in our labs. However, for a weekend warrior those fittings are not cheap and you'll be looking at ~$5 - $10 a fitting for 25 mm versions, versus ~$2 for glav fittings and you will use a lot more than you think. On my system I ended up using 7 elbows and 12 Ts and 10 couplers. The other reason I went Galv was I already had many fittings.

Page 1 of 3 123 LastLast

Similar Threads

  1. Bolts for couplings
    By surfin in forum TRAILERS & OTHER FABRICATED STUFF
    Replies: 21
    Last Post: 31st May 2010, 11:12 AM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •