Railway Preservation News

Westinghouse single lung 11" vs 9&1/2"
Page 1 of 1

Author:  10stewi [ Fri Dec 29, 2017 7:40 am ]
Post subject:  Westinghouse single lung 11" vs 9&1/2"

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?

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

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.

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

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

Page 1 of 1 All times are UTC - 5 hours [ DST ]
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group