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feedwater preheater

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mick H21/08/2019 13:13:45
723 forum posts
21 photos

I am considering fitting a feedwater preheater to a small marine type engine. The heater would be of the "concentric pipe" type whereby the feedwater will pass through a 3/32" copper tube which is jacketed by a larger bore tube.

What bore should I make the jacketing tube ?

What would be minimum length of jacket to be effective ?

How long & piece of string come to mind but if it is of any assistance the pump bore is 5/32" with 3/16" stroke.


duncan webster21/08/2019 15:17:01
2655 forum posts
36 photos

I have no idea how long to make it, but I suggest you put a curl in the inner pipe to allow for differential expansion. If you are using exhaust steam to do the preheating, the surface will get covered in oil, so you need to be able to get it apart for cleaning

mick H22/08/2019 07:07:05
723 forum posts
21 photos

Hallo Duncan. There does not appear to be much interest in this topic. I take your point about the oil. The preheater will have union fittings so that it can be soaked and blown through but it might be wise to also allow a bit more space in the jacket bore. I have already made a condenser and in hindsight maybe the preheater would have been better incorporated into the condenser. Positioning it on the outgoing side of the condenser would cause some problems of space.


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