Taper or Parallel BSP Threads ?

I need to get some fittings to connect up my compressor to a larger receiver and to a pressure blaster. BES seem to have all the various sizes and adapters I need, but most come in both a taper and parallel BSP flavour. Would one design be better than the other for making airtight connections when it comes to the 120psi the compressor chucks out.

Thanks

Jim

Reply to
Jim
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I use female parallel and male taper threads together with PTFE tape for air at this sort of pressure. Seems to work ok.

If I'm making fittings, I can't be bothered to set the lathe up for taper thread turning but instead make the male thread slightly oversize. I cut the female with a tap and dont use the plug tap. This gives a female taper and a male parallel which also works OK again with PTFE tape. I only do it this way as I don't have many BSP dies but a reasonable selection of taps.

Good Luck

Bob

Reply to
Bob Minchin

I've done this exercise, although including setting up a compressed air ring main in the workshop using filter/regulator/lubricators etc.

A better source of supply for all things for compressed air is

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They do a very good catalogue which is rather more usable than their web site.

Regarding threads, the normal use seems to be to use either taper threads with PTFE tape or parallel thread fittings with a sealing ring.

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some ideas on this.

Reply to
Andy Hall

Connecting up to a larger receiver wont increase the CFM of the compressor, so I wouldnt bother with this until you have tried your blast equipment, and have determined whether or not you have enough CFM. You would have a good idea whether or not the set up you have is likely to work, by the size of the nozzle on your blaster..........if its anything much above about 6mm diameter, then its only going to work in short bursts with a 3hp compressor, and you are going to need more CFM to overcome this problem.

k
Reply to
Ken

The length of the "short bursts" being dictated by the size of the receiver I would have thought?

Reply to
John Rumm

The size of the receiver doesnt make the slightest difference to the amount of air being consumed by whatever you have connected to it. Its certainly not worth wasting time and effort sorting out a larger receiver, if you dont have enough CFM to supply your requirements properly.

k
Reply to
Ken

Was not suggesting that it would. Only that doubling the capacity of the receiver doubles the amount of air stored, and hene the length of time you can work before you run out of air. On the down side you obviously have to wait twice as long for full recovery, and the total amount of mins/hour you can run the tool will remain the same - only the duty cycle changes.

Reply to
John Rumm

One wonders if you have actually ever used an air tool of any kind?

k
Reply to
Ken

A few... of them I expect that my small grit blaster and my impact wrench have the highest demands. I can run neither continously on my small compressor - but can still get useful work done with them if I don't mind waiting for the compressor to recharge.

What exactly are you disagreeing with? That a bigger receiver stores more air than a smaller one? Or that it will run a given tool for longer before falling below a useable pressure?

Reply to
John Rumm

kind?

A bigger receiver is definately an advantage. My blasting cabinet uses very slightly more air than my Hydrovane compressor provides (15 cfm I think). I have fitted a vast receiver in the workshop loft space (with an automatic drain valve) which means I can blast for 15 mins or so before the pressure drops too low for effective use. As most of my bits don't take 15 mins to clean, and the time between cleanings is often measured in days rather than hours I can use the cabinet freely at any time. Without the extra receiver this would not be possible. I do have a further compressor that I can switch on to the air ring main if a particularly large job needs to be done but the extra receiver normally suffices and is much quieter !

AWEM

Reply to
Andrew Mawson

I won't disagree with your theory but in practice for shotbasting with a reasonable size nozzle the waiting time for a large receiver to regain useable pressure when driven by a small compressor is _hugely_ annoying.

90cfm is considered almost a minimum, unless you are doing coin size objects in a cabinet. This is what I use.
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Reply to
Mark

Thanks to everyone that posted, ended up with a mixture of taper and parallel depending on what combination of fixings I needed !

I'm only doing a Spitfire restoration so don't want to spend vast amounts on compressors, receivers etc. I've currently got a 3HP 10CFM compressor with a

50 litre receiver and the secondary receiver is approx 300 litres. I'll give this combo a go and see how I get on.

Thanks again

Jim

Reply to
Jim

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember John Rumm saying something like:

Ignore Ken; he's just a trolling idiot. You'll notice he hasn't come back to prove you wrong, he just gets abusive when anybody notices he's full of compressed air.

Reply to
Grimly Curmudgeon

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