jackrae
Elder Statesman
Posts: 1,333
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Post by jackrae on Jan 18, 2014 16:24:56 GMT
In this month's EIM the author, Gordon Smith referred to the use of a triple action test pump to minimise "pulsing" during boiler pressure tests. Can someone advise what a triple action pump actually is. And just to expand on the theme, has anyone got the perfect design of boiler test rig (pump + manifold + valving etc).
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Post by Deleted on Jan 18, 2014 17:09:58 GMT
I've heard of double action pumps where there is a smaller diameter ram inside a larger one. The first part of the stroke just moves the smaller ram and further movement then moves the larger ram. You can use the full stroke to fill the boiler etc. rapidly and then short strokes to add water more slowly and bring up to pressure gradually. Haven't heard of a triple action pump though.
My test rig consists of a set up for testing central heating systems etc. purchased s/h off Ebay. It's fully self contained with tank, pump, gauge and two valves. When I bought it the glass on the original gauge was broken so I fitted a new calibrated one although the original gauge still worked ok.
John
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Post by modeng2000 on Jan 18, 2014 17:17:54 GMT
A triple action pump is probably one having three single acting pumping cylinders on a crank set at 120 degrees from each other.
There are some water powered engines constructed like this. One is preserved in working condition at Twyford Waterworks.
John
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jma1009
Elder Statesman
Posts: 5,900
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Post by jma1009 on Jan 19, 2014 0:18:29 GMT
hi jackrae,
all the boiler test rigs ive used (and made) have a single acting pump in a water tank that pump into a reservoir tank to which the main calibrated test gauge is attached. there is always a screw down valve on the supply from the pump to the tank to prevent leakage back through the pump and it's clacks, plus another screw down drain valve. from this tank goes the pipe connections to the boiler. under no circumstances must the pipe be connected to a clack valve on the boiler being tested unless the ball has been removed from same first. most of us have a box of fittings and adapters to suit various boiler fittings, a 1/4" x 40 tpi connection somewhere usually being required for the pipe connection from the test rig or alternative 5/16" x 32 tpi connection pipe being provided too.
i dont see the need for a triple ram pump if the pump firstly pumps up the reservoir tank. a single ram pump is perfectly adequate and indeed just a small movement on a single ram pump builds up the pressure very quickly so long as no air in or leaks on the boiler being tested.
cheers,
julian
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jackrae
Elder Statesman
Posts: 1,333
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Post by jackrae on Jan 19, 2014 9:52:14 GMT
Hi Julian, That's exactly how our existing club test pump works. It's just that I was interested in what the article author referred to as his "three throw" test pump (apologies for previously saying triple action) - which he built to minimise pressure impulses to the boiler and the possibility of cold working the copper.
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Post by Deleted on Jan 19, 2014 17:34:49 GMT
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Post by modeng2000 on Jan 19, 2014 18:50:08 GMT
That's an interesting site John.
John
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Post by ejparrott on Jan 21, 2014 16:41:21 GMT
single acting pump for me
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uuu
Elder Statesman
your message here...
Posts: 2,807
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Post by uuu on Jan 21, 2014 19:12:30 GMT
I'll second that. It's trouble enough building and maintaining a loco without adding complexity into ancillary bits. Pump more gently, if you want to.
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