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 inches of water (that’s why arterial bleeding can make such a mess) and car tyres will be about 830 in.
Stops & Pipes Page 5
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.