Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Hi Rich,

Yes, that's the spring I used on my "Quality Brand" B30. I don't remember if I had to shorten it or not. I think I did. I think the 1" length was too long for the screw I used. Note that the original springs seem to lose compression over time.

I made an adapter fitting to pressure test the safety valve on the B30. It's just a piece of 3/4" hex brass with a 1/4" pipe thread on one end and a 1/8" pipe thread on the other:

[ Guests cannot view attachments ]

I believe the thread on the stack safety valve is a 1/8" straight pipe thread ("BSPP"), a taper pipe tap will work if you don't tap too deep. With the valve/stack installed, the pressure regulator can be slowly turned up until you just hear a slight hissing from the open end of the stack. Also, you could use liquid soap, or something similar, to detect leakage. I set the valve on my B30 to 25-30 PSI.

Paula