Pipework for fixed airline

[richweld]

Decided it is time to install a fixed airline in my garage/workshop. I shall be using 15mm copper pipe. Have looked at earlier threads for ideas. Now it is time to make up an order.

I'm proposing to use ring solder joints (where possible) plus compression.

What is the difference in quality between Yorshire and Flowflex (Yorkshire fittings are more expensive) and where is a good place to buy (online or local plumbers merchant)? I have been looking at Screwfix for prices.

 

[rtbcomp]

I buy mine from Screwfix and use capillary rather than solder ring, much cheaper. I do use solder ring in awkward places.

If you need to interface copper to BSP fittings :-

The thread on 15mm compression is 1/2 BSP
10mm microbore = 3/8
8mm microbore = 1/4

MOST of the time! I got some 8mm microbore fittings from B&Q with funny threads,

Or you can buy so called "iron" connectors, for example "15mm to 3/4 iron" will connect 15mm pipe to 3/4 BSP. These are made out of brass, not to be confused with malleable iron fittings.

Also look here http://www.mig-welding.co.uk/air-system.htm
I've also connected 1/4 bsp fittings directly to 8mm pipe using the nut & olive from a compression fitting.

 

[richweld]

Thanks for those details. I had seen the seen the link.

I notice Malcolm uses lever ball valves to act as drain valves on the downpipes. Is that what other folk have used? A central heating drain valve would be less expensive, but a bit fiddly to use.

The thing I haven't quite worked out yet is the easiest way to connect the 1/4" BSP connectors (one male and the other female) of my 2 compressors to 1/2" pipework. I think I'll need some hex nipples and reducing bushes, plus a flexible pipe/tap connector?

I cannot connect my 2 compressors direct from the tanks (like Malcolm's photo) becasue one compressor is rated 10 bar and the other 8 bar, so I need to regulate the pressures.

 

[rtbcomp]

.........
I notice Malcolm uses lever ball valves to act as drain valves on the downpipes. Is that what other folk have used? A central heating drain valve would be less expensive, but a bit fiddly to use.

.

I use ball valves, the difference in cost can't be that great. BTW use valves specified for compressed air, some of the smaller ones have a one-way action and can leak.

The thing I haven't quite worked out yet is the easiest way to connect the 1/4" BSP connectors (one male and the other female) of my 2 compressors to 1/2" pipework. I think I'll need some hex nipples and reducing bushes, plus a flexible pipe/tap connector?

Get some proper air hose, rubber is best, nylon is cheaper, use hose tails to get to your BSP threads, Machine Mart do a good range and you can have a rummage if you're not sure what the proper name for things is.

I cannot connect my 2 compressors direct from the tanks (like Malcolm's photo) becasue one compressor is rated 10 bar and the other 8 bar, so I need to regulate the pressures.

You probably can, the tanks are most likely safe to 20 or 30 bar. You need the compressors set to different pressures so they don't switch at the same time. You must avoid having high pressure on the output of a regulator because it will bleed air to atmosphere.

 

[Shox Dr]

Yorkshire fittings are for lazy people with more money than sense. Buy Index they are a fraction of the cost.

 

[richweld]

the tanks are most likely safe to 20 or 30 bar. You need the compressors set to different pressures so they don't switch at the same time. You must avoid having high pressure on the output of a regulator because it will bleed air to atmosphere.

One compressor tank (Clarke) is stamped 11 bar and the other (Wolf) 10 bar. The Clarke fills to 10 bar with cut in at 8 bar. The Wolf fills to 8 bar with cut in at 6 bar.

If I connect the 2 tanks direct to the fixed airline, then the Wolf will try to fill up to 10 bar, but won't the pressure relief valve cut in before it gets to 10 bar?

I was going to use these valves:
http://www.screwfix.com/prods/13103...Valve-15mm;jsessionid=XJINFWWE0ZOZQCSTHZOCFFI

 

[eil]

Hi rich
You need to connect one 1/2" bsp check valve and a ball valve to your wolf and one ball valve to the clarke before joining them together with a T piece then pipe from your T to your filter/regulator.
The wolf wont try to pump up to 10bar because its set for 8 bar. but will blow the relief at about 9 bar. that is why you need to install a check valve on the outlet of the wolf.
Two ball valves mean you can use just one at a time when you dont need too much air eg blowing up tyres, shut the clarke ball valve and leave the compressor off just use the wolf.

 

[rtbcomp]

..
I was going to use these valves:
http://www.screwfix.com/prods/13103...Valve-15mm;jsessionid=XJINFWWE0ZOZQCSTHZOCFFI

I use those, they're fine.

Forgot about the relief valve, as Eil says you need a check valve. Get a proper compressed air one, I tried a Screwfix one and it didn't like compressed air, the rubber went all squishy.

Make sure you get the check valve the right way round, it needs to let air flow from the lower pressure tank to the higher, so the latter doesn't over-pressure the former.

 

[richweld]

Thanks for those details.

I'm persuaded that connecting the 2 compressor tanks to the fixed pipeline is the way to go. Now a have to find a 1/2" BSP non return valve. Cannot find anything suitable from Screwfix. May have to try local plumbers merchants.

Machine Mart have 3/4" and 1" non return valve for use with a pressure switch control, but no 1/2".

 

[eil]

Here and have a rummage around the rest of the site
http://www.airlines-pneumatics.com/webcat/Detprod.asp?ProductCode=S070135

 

[rtbcomp]

I use the link Eil posted - excellent service.

Don't bother with plumbers merchants, and the NRVs MM sell are for connecting a pump to a tank, not what you really need.

 

[richweld]

The pipework is almost finished. Now I'm wondering whether it was a good idea to use solder joints. It is much neater than compression, but is all that flux in the pipe going to be a problem? I suppose the filters will take care of it.

With water pipes don't plumbers flush the pipes out or is that just for potable (drinking) water? Can't flush an airline can you?

BTW. I didn't use a non return valve. The cost of the valve + postage was excessive. Instead I lowered the cut out pressure on the Clarke compresssor to 8.2 bar (120 psi). The Wolf cuts out at 7.8 bar.

 

[Jaeger_S2k]

You shouldn't get flux in the pipe.

When you flux for a solder joint, clean the pipe with fine wire wool or a cleaning strip Abrasive Cleaning Strips or wet and dry.

You then flux the pipe ONLY, no flux should be applied to the fitting!

Flux is a corrosive component and will continue to eat the copper if not treated/handled/applied correctly. Best flux for all situations is LA-CO Regular Soldering Flux it's acid free and easily soluble in water.

Clean the pipe the depth of the fitting and only wipe the pipe with enough flux, not that it looks like you've dipped it in, it should look wet as if you've oiled it.

Tip - As you heat the joint heat it from either ....

Coupling - Middle and back of coupling, if the backs against a wall, middle and bottom.

Elbow - Middle and Outside of elbow not the inside corner.

DON'T TOUCH the fitting with solder until the Flux boils, it's not hot enough and you'll waste gas and probably stick to the fitting.

Once the flux boils move the flame away and give the edge of the fitting at pipe a lick of solder, you should see it run around the joint and the edge turn silver.

Heat again this time towards the unsoldered end of the fitting, remove heat and lick the solder. If the solder isn't running on contact with the fitting apply some more heat. But don't be tempted to run the solder by flashing it with the flame. That will result in the solder being molten but the pipe and fitting NOT being hot enough.

It's the heat in the fitting that melts the solder, the flame heats the fitting.

Once solder is applied after 10 to 15 sec, you can apply a wet rag/towel to the joint and cool it, once cool enough it should be washed to remove any excess flux from around the joint and any that has run down the pipe (but that'll only happen if you put too much on).

The regulations (water and gas) stipulate you should apply only enough flux to do the job, to me that's always just a wipe, never cakes of it. The flux mentioned above is preferred when working with gas as it's inert when not heated.

Following the above should result in little if any flux being left inside the pipe.

 

[rtbcomp]

I echo Jaeger's remarks. The old fashioned Fry's flux will corrode the copper, but I doubt if it will corrode all the way through. Modern fluxes seem milder.

It's very tempting to put too much solder on the joint, a bright ring all around the joint is sufficient. Also try not to set fire to the flux, the soot formed will give a bad joint.

You could always flush the system with water before connecting up to regulators and compressors.

 

[Jaeger_S2k]

I think it's the overflow from the days of Boss White and gas fitting "you can never have too much Boss White" that was carried over to "you can never have enough flux" which is/was quite wrong.

If you have any like powerflo and similar, just wipe a load on a piece of old copper and leave for a couple of days, the longer you leave it the greener it'll become, the green stuff is the copper pipe that's been dissolved.

Another favourite flux

But if you don't have a call for flux in medium to large quantities the La-co comes in a 60g tub (that's the one that I keep in my tools box, and refill it from the 450g tub in the van)

Yeah, a flush with water isn't a bad thing, it'll be easy to blow through once the compressor is connected up and running.

Just open you water trap tails and flush, once up and running you'll have water in there anyway but for the first week or so, or the first view runs open you drain off tails every couple of hours.

 

[rtbcomp]

........
If you have any like powerflo and similar, just wipe a load on a piece of old copper and leave for a couple of days, the longer you leave it the greener it'll become, the green stuff is the copper pipe that's been dissolved.

.....

I once installed some complicated pipework by fitting it all loose and coated the joints with flux. I left it overnight with the idea of soldering it up next day, when I arrived in the morning all the joints had turned green and the whole lot had to be dismantled, cleaned and re-fitted - lesson learnt!

 

[richweld]

I used the LO-CO flux and applied a smear with the lid brush to both the outside of the pipe and the inner rim of the fitting. My old DIY plumbing books say to apply flux to both surfaces. That may not be current best practice!

I used solder ring fittings; wiped off excess flux from outside of pipe; and cleaned up the pipe after soldering. I may have used a bit too much flux.

I have tested the pipe for air tightness, but haven't connected the filters. I'll now run some water through the pipes to clean out any residual flux.

Thanks for the tips.

 

[Jaeger_S2k]

Yeah,
The old way was flux everything, or maybe that was the 'belt and braces' way

It's not a problem but it will fair better if you flush, as the flux will have shouldered on the pipe as you inserted it into the fitting cleaning the flux off as it went in.

You'll have noticed the same on the fitting shoulder as you inserted the pipe.

Best to flush it as the flux will have melted and be lying inside the pipe you don't need that coming to your filters. Once flushed leave open to the air for a while and it'll dissipate especially in this fine weather, warm but not too humid.

You'll be fine. Just get your book out and put a line through, 'apply flux to fitting'

Another tip - If space allows, when you slide the fitting onto the pipe just spin the fitting on the pipe, or spin the pipe inside the fitting. It's sometimes not feasible due to walls, joists etc being in the way but it gives the flux a 'wipe' round the pipe and fitting.

 

[richweld]

The pipework is now finished, flushed with water, and afterwards with some air.

I put some 'tails' on the drain pipes so that they drain straight into a bucket. I used ring solder fittings and this time just put flux on the pipe (not the fitting). Big difference. No residual flux inside the pipe.

Found the WRAS publication on use of solders and fluxes. Here is link to the PDF. It is well worth a read.

http://www.wras.co.uk/PDF_Files/SoldersFluxes2.pdf

Thanks again for all your advice.