dual crosshead pump plumbing?

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Fred_V
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dual crosshead pump plumbing?

Post by Fred_V » Thu Oct 04, 2018 7:50 am

A friend has an American 7+ ga. that has dual crosshead pumps. He is restoring the engine and wants to know the best way to plumb the pumps. As I remember it I think the outlets are connected together across the engine. The bigger question is about the supply and bypass lines.
Thanks,
Fred V
Fred V
Pensacola, Fl.

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Fred_V
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Re: dual crosshead pump plumbing?

Post by Fred_V » Thu Oct 04, 2018 12:26 pm

here are photos of his setup. they were right side up on my computer. the 2 pumps are connected together at both the inlet and outlet going to one boiler check.
is this a good way to do it?
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20171030_172803.jpg
20171030_172748.jpg
Fred V
Pensacola, Fl.

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DianneB
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Re: dual crosshead pump plumbing?

Post by DianneB » Thu Oct 04, 2018 10:14 pm

Talk to Jesse Banning (http://www.banninglocomotiveworks.com/home.html) He has made some changes that work wonders.

hoppercar
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Re: dual crosshead pump plumbing?

Post by hoppercar » Thu Oct 04, 2018 10:43 pm

my 2 pumps are not connected together at either the inlet or delivery side. they are both piped to there own seperate boiler check valve









my 2 pumps are not connected either at the suction side or the delivery side. ...they both have seperate bypass valves and seperate boiler check valves.

RET
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Re: dual crosshead pump plumbing?

Post by RET » Fri Oct 05, 2018 9:21 am

Hi,

Because they are crosshead pumps, the pumping action will be 90 degrees out of phase so each pump is going to need its own inlet and discharge check valve. If they don't, the pumps will still work, but at a much lower efficiency (about 50%). They can be piped together as shown, but only after the check valves. A little thought will show why this is necessary.

In the pictures shown, the supply and discharge check valves need to be in the vertical part of the pump assembly. Check and see if there are checks there already, if not, install them. After the check valves, the water can go into one boiler check valve leaving the other for an injector, hand pump, etc. As Bill Shields says, you can't have too many ways of putting water into the boiler, although I must say that using a hand pump for boiler supply gets old in a hurry.

Richard Trounce.

Kevin S
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Re: dual crosshead pump plumbing?

Post by Kevin S » Fri Oct 05, 2018 2:31 pm

On my American, I have them plumbed separately and each go into the boiler separately. On one side I have my hand pump plumbed into the supply side, so this side will always put water in. On the other side, I have a bypass plumbed in between the pump and the boiler check valve, so I can regulate how much water goes into the boiler. I have not had an issue with it plumbed this way.
Kevin S.

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Fred_V
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Re: dual crosshead pump plumbing?

Post by Fred_V » Sat Oct 06, 2018 7:34 am

Thanks to all. I believe the pump checks are in the square part of the pump body so that should be OK. He is adding an injector.
Fred V
Pensacola, Fl.

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Bill Shields
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Re: dual crosshead pump plumbing?

Post by Bill Shields » Sat Oct 06, 2018 7:52 am

do not depend on the checks INSIDE the pump to isolate the boiler...you don't want hot water / steam getting to the water end of the pump.

best for each pump to have its own 'into the boiler' check valve...otherwise one leaky check can bring down both pumps.

Feed lines are another matter. as long as you can totally isolate a pump from the feed line, you should be ok.

Worst case is you get an air leak in the feed end of a pump (leaky packing or blown gasket), and as a result, you lose BOTH PUMPS because they are sucking air.

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Fred_V
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Re: dual crosshead pump plumbing?

Post by Fred_V » Sat Oct 06, 2018 8:00 am

Hmmm. I was worried about the inlet side. He has boiler checks already and will add another one for the injector. I think separating the pumps would be a better way but a bit more complicated.
Thanks.
Fred V
Pensacola, Fl.

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