Boiler heating area calculations

[pkastagehand]

I will soon need safeties for my A3 boiler in 3/4" scale. Since the A3 book was published Kozo has updated his safety design and this updated info is in the New Shay book. I have that information describing building them based on boiler heating area, etc. I wondered if anyone has done a spreadsheet for calculating the boiler heating area based on this information that they would be willing to share?

I was going to do it but it seems silly to "re-invent the wheel". I like to use spreadsheets rather than calculator (or pencil and paper) since I can "save the numbers" and recalculate at will if I make any changes to things I'm working on.

Paul

[Ed Hume]

Paul,

If you do the calculations you'll wind up with the same size ball and seating hole which dominate the relieving capacity. The differences of the new design are to make it easier/more reproducible to fabricate and to provide a tunable orifice.

Ed

[pkastagehand]

May 1, 2012 10:39:44 GMT -5 Ed Hume said:

Paul,

If you do the calculations you'll wind up with the same size ball and seating hole which dominate the relieving capacity. The differences of the new design are to make it easier/more reproducible to fabricate and to provide a tunable orifice.

Ed

By same size, you mean same as what he calls for in the A3 book? That is assuming I made my boiler the same as his.

My boiler is steel with 5 flues instead of 3 and has a flat topped firebox with additional stays instead of girder stays. But you're right, after doing the calcs I chose the 3/16 ball size. Next size down was borderline.

Paul