ace
Statesman
Posts: 528
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Post by ace on Aug 28, 2008 20:36:55 GMT
Hi folks
Has anyone got any suggestions on how to make a simple hydraulic boiler testing kit complete with pressure gauge. I have compressed air and various pressure gauges and would like something that I can set up with ease.
Cheers ace
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Post by AndrewP on Aug 28, 2008 22:38:09 GMT
Mine consists of a hand feed pump, fed from a water reservoir, pumping into a couple of tees via a non return valve. So I have 3 outlets - 1 to the boiler via a flex pipe, one to the pressure gauge and one to a valve to let the pressure out gently! Don't forget the last one because if the boiler is a good 'un removing a blanking plug with 160psi on it is a little nerve racking - just don't ask If that's double dutch I'll take some pics tomorrow. Oh, and before somebody else jumps in, please just use water, NOT compressed air - big bangs, nasty sharp bits of metal sticking out of body, etc etc
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Post by alanstepney on Aug 28, 2008 22:53:55 GMT
In the interests of safety (I dont like us losing forum members) can I just emphasise Andrews last comment.
Do NOT under any circumstances use compressed air to test a boiler.
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Deeja
Seasoned Member
Posts: 131
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Post by Deeja on Aug 28, 2008 23:06:52 GMT
Mine is a small hand pump (like a tender hand pump) and a small tank for a water supply, pressure gauge, and a 1/8" pipe long enough to bend to boiler, unions, etc. Completely fill the boiler with water, and use pump for final bit. A small pump enables accurate test pressure setting.
As above, NEVER use compressed air (may lead to explosive failure if testing any defective parts), only water.
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Post by circlip on Aug 29, 2008 8:05:33 GMT
And just to emphasize Ace, Doon't use thi compresser, tha barn ta mame thi sen if tha uses air! Regards Ian.
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abby
Statesman
Posts: 925
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Post by abby on Aug 29, 2008 8:56:12 GMT
The simplest "hydraulic kit" a pressure gauge and a gas torch. Completely fill the vessel with water and blank off , apply gentle heat , as the water expands up goes the pressure , unless you have a leak of course!
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Post by havoc on Aug 29, 2008 10:05:51 GMT
Can be done, but then make sure you have a relief valve and use a candle to start. If you heat to hard the pressure can rise very fast and high. So a relief valve is a must and gentle, gentle is the message.
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Post by Tel on Aug 29, 2008 11:15:15 GMT
..... and I'll stand behind a large tree while yer doing it, if nobody minds.
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Post by alanstepney on Aug 29, 2008 12:16:07 GMT
The operative word with this method is COMPLETELY.
In fact, fill the boiler and leave it in the sun and you will be surprised how quickly and how much, the pressure rises. (Assuming there are no leaks of course.)
As it is barely controllable, I'll stand behind Tel (& the tree)!
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tcase
Involved Member
Posts: 52
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Post by tcase on Aug 29, 2008 13:05:29 GMT
The valve to let the pressure down gently is quite important, if you let the pressure down in a rush you easily damage the pressure gauge, bending the needle at least !
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firebird
Seasoned Member
Conway now up and running
Posts: 148
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Post by firebird on Aug 29, 2008 18:29:14 GMT
Hi There is a topic entitled 'WHAT IS IT' on this forum that shows my attempt at boiler making. I am now at the stage where I need to hydraulic test it so I have made a small hand pump that will be part of a test rig I am building. Heres the pump. I have made some drawings, I'll upload them if would help you. Cheers
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Post by davidimurray on Aug 29, 2008 19:15:56 GMT
Oww - what a lovely looking pump. Very nice work
If you don'y mind uploading your drawings it would be much appreciated.
Cheers
Dave
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abby
Statesman
Posts: 925
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Post by abby on Aug 29, 2008 20:17:22 GMT
mmmm - some strange views and comments ,the basic law of hydraulics says fluids cannot be compressed , a boiler or any system subject to hydraulic pressure contains no more liquid than its volume and therefore cannot explode , it may burst but at that point all pressure has gone. Havoc I have used this method for 40 years and although I said gentle heat in practice it takes quite a bit and removal of the heat source results in an immediate pressure drop giving very accurate control. I have a very good friend who is a commercial boiler builder and what does he use to test all gauges of boiler ? his compressor , set at 100 psi.
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Post by havoc on Aug 29, 2008 20:36:14 GMT
Abby, this isn't a strange view. When you fill it completely and heat the pressure can mount very high and you only want to go to twice working pressure. For small boiler holding them in your hand can be enough. So when I say to heat it gentle it isn't out of fear of a boiler explosion but of stressing it beyond what is needed. As you say when it is filled with water there cannot be an explosion. There is an account somewhere on the net of a 7.25" boiler tested this way by putting it out in the sun and going to dinner. Can't find it back at the moment.
Only problem with that method that I see is keeping the pressure steady for 15 or 30 minutes.
Actually I use a bicycle tire pump but I fill the boiler with water. Only the gauge and a piece of hose have air in them. But then this is for gauge 1.
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brozier
Part of the e-furniture
Posts: 335
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Post by brozier on Aug 29, 2008 21:33:33 GMT
Nice looking pump firebird,
How did you get it so shiney with such dirty hands ;D
I'd like a look at you drawings too if poss. Need to make my own test kit at some point....
Cheers Bryan
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firebird
Seasoned Member
Conway now up and running
Posts: 148
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Post by firebird on Aug 29, 2008 21:51:27 GMT
Hi I messed about with several methods, stainless steel balls, springs etc none of which I could get to work/seal properly but this method using 'O' rings works well. This is a general arrangement drawing Heres a detailed, actual size and dimensioned drawing. I printed out a blown up drawing thats easier on these eyes of mine. Heres all the parts laid out on the blown up drawing. Bryan, just a quick buff up to clean up the finished pump but all the muck does get on your hands when using a buffing wheel. Cheers
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ace
Statesman
Posts: 528
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Post by ace on Aug 29, 2008 22:22:02 GMT
As per usual loads of great ideas and good advice, just one thing I didn't fully understand and that is ......... 'leave it in the sun' ............... what's that look like then. ;D ;D ;D (living in wet Manchester).
Firebird grateful if you would upload the drawings, looks like just what I'm after.
regards ace
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Post by alanstepney on Aug 30, 2008 0:38:45 GMT
Abby is correct, BUT, only if there is no air whatsoever in the boiler.
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steam4ian
Elder Statesman
One good turn deserves another
Posts: 2,069
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Post by steam4ian on Aug 30, 2008 7:11:10 GMT
G'day all
Has anybody made a gauge tester to go with the boiler test set? They are not much more than a plunger in a vertical cylinder. The plunger has a scale pan on top on which you place various weights. The cylinder is blind at the bottom except for a connection to the test set. The pressure at which the plungerr just lifts corresponds to the mass on the scale pan multiplied by the area of the plunger. To overcome stiction the scale pan is rotated on the balancing fluid.
Any old school instrument techs would recognise the device.
Must build one after the round tuit.
Regards Ian
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cotswold
Part of the e-furniture
Still testing the water
Posts: 307
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Post by cotswold on Aug 30, 2008 7:15:12 GMT
The operative word with this method is COMPLETELY. In fact, fill the boiler and leave it in the sun and you will be surprised how quickly and how much, the pressure rises. (Assuming there are no leaks of course.) As it is barely controllable, I'll stand behind Tel (& the tree)! I have seen a boiler taken up to 1.5 times working pressure (150 psi) in bright sunshine. Within less than 10 minutes the pressure had risen to 180 psi and was still rising - at which point the tester declared the boiler as passed!
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