This is cambridgeorganists.org Designed and produced by Stephen Taylor for the Cambridge & District Organists’ Association
No. 10 Under pressure
Organ wind pressure is measured in inches of water -
A Wurlitzer cinema organ housed in an old water mill which was my introduction to the world of organs ran on 10in. A lot of time was spent sticking gaffer tape on junctions in the trunking as the escaping air caused significant noise.
Large cathedral organs run on several pressures -
This sounds a lot and indeed it is difficult to convey such wind pressure without leaks and noise, but 50 inches of water is a mere 1.8 pounds per square inch.
Your blood pressure is about 75” of water (that’s why arterial bleeding can make such a mess), your gas supply is 289”, car tyres are about 830” and High Pressure gas mains are above 2800” (the pressure varies as they are for storage as well as transmission).
Author’s gauge. Red lines are at half inch intervals with maximum reading of 5 inches. The left hand limb is connected to the chest so water rises in the right side as it falls in the left, the difference in height being measured against the half inch divisions.