Model Engine Maker
Help! => Specific Engine Help => Topic started by: sshire on August 30, 2013, 01:49:14 PM
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For some reason, when I got the PMR boiler kit, I also ordered unions, els, t's, etc in 3/16"
Last evening I was reading, in Harris' boiler book, that the piping should have an i.d. of cylinder bore X 0.3 for a 2 cylinder engine. The Pumping Engine has a bore of .625. So .625 x .3 = .1875. This is the i.d. of 1/4" piping.
Will piping in 3/16" restrict something that shouldn't be restricted or reduce the efficiency of the engine?
Best
Stan
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Smaller diameter water pipe just means the water will have to travel faster (= at a higher pressure) through the pipe, the pump will still displace the same amount of water per stroke.
So what does that mean? : the increased resistance of the water travelling through the pipe might make it harder to pump. The volume of water available is being limited by the person operating the handle of the pump and the pump's volume, not the pipe.
Jo
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Hi Stan,
Harris's calculations are for the Max efficiency, with a difference of 1/16" diameter in the inlet I don't think you will notice much difference. More inportant is to make sure that you do not restrict the exhaust, use as lage a pipe on it as you can.
Regards,
Gerald.
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Thanks much.
I'm using 1/4" tubing for the feed pump, but will stay with the 3/16" piping for other boiler connections to the lubricator and to the engine inlet. I'll go 1/4" for exhaust piping to and from the oil separator.
Good news, as I have quite a few 3/16" fittings.
Best
Stan