Valve as Relief Valve
I have been looking for a reservoir relief valve system which will provide
positive sealing when closed, minimal pressure to keep closed, and easy opening.
It would seem best to have the pressure of the air in the reservoir providing
the force to seal the valve instead of depending on a spring strong enough
to hold a cover shut against the pressure. The Open and Shut action is very
quick, but I have found that the sound of the organ does not notice this.
In my internet reading of hobbyist Busker Organ construction I came across
the website of Bernard
and Philippe. It is filled with ideas and technical information about building
They have a page describing valves called Tangential Membrane valves (TMC)
and Concentric membrane valves (VMC). They are using the valves in an organ
reading music books. I thought, here is a solution to my
relief valve problem! A very small control pressure will hold the valve
closed and a very simple lever will open a small hole which will open the
actual large valve releasing a useful amount of air when required. Some diagrams
show what is happening.
Construction may be challenging but the only part which is critical is the
seal for the top chamber and the seal of the membrane on the input tube.
Dimensions are not critical and can be adjusted for your particular installation.