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[firedup]

Just finished the feed pump the last one was geared down too much thought I might share.
http://www.youtube.com/watch?v=InxZESvv-v4
Mark

[derekwarner]

Very nice firedup...... .....Derek

[KBIO]

Hello Firedup!
Very nice piece of equipment which looks very reliable! 
thanks!

[derekwarner]

firedup...I should have asked  ...


1. you mentioned that you increased the pump speed ratio...was this just trial & error  to result with a boiler water feed volume that approximated the water consumed as steam in the boiler?
2. being a fixed displacement concept...the make up water volume will always be relative to the engine speed & again the steam/water consumed etc
3. do you use a simple nitrile o-ring & teflon back up as the piston seal or a nitrile cup seal [Polypak style]?
4. we could attempt some rough calculations on the actual power required to maintain the water displaced per revolution against [into] the ....3 Bar boiler pressure & whilst the power will be very low.... ...it is still a %  ratio to the actual engine output power ....very interesting  .....Derek

[firedup]

To answer some of the points you raised:
Trial and error (infact that seems to have been a pattern building this engine )
I am trying to go for over kill and will use a bi pass valve to take away the surplus
I have used neither its a bronze ball sitting on a reamed hole
Lost me on the last point Derek

[derekwarner]

Thanks firedup.....another question for any member who uses a boiler water make up pump.... 

'Is there a prefered location for the make up water to enter the boiler?'.....the reason I ask this is I think we need to [ignore in this case] the theory of fluids & pressures .....

1. if we T the make up water @ say 3 Bar into the line from the boiler to the gas regulator [which would be a very close & convenient location]  ....the gas regulator diaphram will be subjected to X pressure pulse per engine RPM [or the driven reduction ratio]
2. if we were to have the same 3 Bar water volume & X pressure pulse per engine RPM enter the boiler in the top steam space [above water level] the pressure pulse will be dampened in steam which will act as an accumulator so the resultant pressure spike at the gas regulator is greatly reduced 
3. with a twin cylinder double acting engine.....we also have four steam pressure reduction pulses per RPM!!!

All I am trying to understand is how to best minimise the pressure pulsations on my Anton V71 gas regulator neoprene diaphram  .......................Derek

[gondolier88]

Hi Derek,

The volume of water entering and steam exiting at these sizes really doesn't make any appreciable pulse- though any well designed boiler shouldn't have a pulse from steam take-off as the supply pipework dampens it along it's length meaning the boiler sees a continuous take-off rather than pulses- though if you gauge the supply pipe after the main stop valve you would see the effect, getting more exxagerated the nearer you get to the engine.

However if you were looking to reduce any pulse there may be;

 I havn't used a pressure regulated gas supply on a model, but can you take the diaphragm pressure supply from the steam space- as long as there is condensate in the pipe, which there would be as soon as you start the burner, then there would be a hydraulic link from the steam to the diaphragm.

As you say- mount the check valve into the steam space and there will be a limited pulse from the feed water supply.

Greg