Re: Safety Valves
Posted by: Jeff Theobald
Date: May 12, 2006 07:56AM
I thought we had already established the operation of the Stanley safety valve in previous correspondence.
Your description of the operation of the Stanley safety valve is correct, which is why it is neccassery to have it set about 100psi above maximum working pressure. As I said before it is not uncommon under certain circumstances to see the steam pressure 50psi above maximum working pressure.
The only time I have know safety valves to open, is as you have said, when firing with too high a water level, and when not paying attention and leaving the hand bypass in. This soon wakes up an operator of a car, to the fact that something is wrong, and as you say the safety once lifted will not shut until steam pressure has fallen far below working pressure.
The Stanley safety valve as you have said, would be unable to release the steam being generated by the larger boilers, but here is where the capability of being able to instantly remove the fire comes in, if the safety valve has operated because the steam auto has stuck or has a small bit of dirt in it, allowing the burner to continue burning, the manual override will save the day.
Golden rules never leave a steam car during steaming; never leave a steam car, parked with the main fire held off by the automatics.
Hope this adds to your thoughts, all the best, Jeff.