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 Post subject: Westinghouse single lung 11" vs 9&1/2"
PostPosted: Fri Dec 29, 2017 7:40 am 

Joined: Wed Jun 13, 2012 10:38 pm
Posts: 341
Location: Copenhagen, Denmark
Comparing the two air pumps, what is the cubic volume output of air from both models per stroke or per minute? Also if anyone knows, what is an average steam consumption figure of the pumps while they are operating?

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Stuart Harrod
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Nordsjællands Veterantog
Veterantoget.dk


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 Post subject: Re: Westinghouse single lung 11" vs 9&1/2"
PostPosted: Fri Dec 29, 2017 8:57 am 

Joined: Sun Aug 22, 2004 7:19 am
Posts: 6394
Location: southeastern USA
Bernie Watts at Backshop Enterprises is the go to guy for not only the WABCO data, but real world information on what you can really expect in service. He's in suburban Denver 303-424-6882.

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“God, the beautiful racket of it all: the sighing and hissing, the rattle and clack of the cars over the rails. These were the sounds that made America the greatest country on earth." Jonathan Evison


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 Post subject: Re: Westinghouse single lung 11" vs 9&1/2"
PostPosted: Fri Dec 29, 2017 4:36 pm 

Joined: Thu Aug 05, 2010 2:06 am
Posts: 329
Hi Stuart,
According to my 1913 I.C.S. Westinghouse Air Brake handbook at 200psi boiler pressure and maintaining a constant main reservoir pressure of 130 psi the 9 1/2" will deliver 39cfm of free air and the 11" will deliver 58cfm. The 9 1/2" will consume 60 lbs. of steam while the 11" will consume 58 lbs. per 100 cubic feet of free air delivered.

The same book states the bore and stroke to be 9 1/2 X 9 1/2 X 10 and 11 X 11 X 12 respectively. I don't intend to be a smart a$$ but a bit of arithmetic will give us the cfm per single stroke. The area of the base X the height gives the volume of a cylinder and the literature commonly ignored the volume taken up by the piston rod on every other stroke. Radius squared X pi X stroke = cubic inches then divide by 1728 (cu. in. per cu. ft.) to = cubic feet.

If I did my math correctly the 9 1/2 figures out to be 708.8 cu. in. per stroke or .41 cubic feet.
The 11 comes out to 1140.4 cu. in. or .66 cubic feet per stroke.

For the rest of your question, as stated in the handbook, the averages will depend on your operating conditions of boiler pressure & main reservoir pressure. I hope this is what you were looking for....mld


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