Airflow Measurement Equipment
By Phil Dayson
|Some of the MMD group may be interested in a piece of equipment which I have built in order to _measure_ the leakage in pneumatic components.|
Most of the existing leak detection techniques, no matter how sensitive or elegant, are comparative in nature only. In an attempt to put more science and less "black magic" into my piano restoration I have developed a quantitative leak measurement system.
Using this equipment the actual leakage of pneumatic parts can be measured in cubic inches per minute. (Ampico certainly used to measure component air consumption and leakage. In a series of technical ads in 1929 Ampico boasted of their research labs ability to measure leakage in cubic inches per minute. See AMICA News Bulletin March\April 1992 pages 15-24.)
The equipment can measure leaks from about 3 to 30,000 cubic inches per minute. To put some meaning to these figures, here are a few measurement which I have made:
The variety of components that can be tested is virtually unlimited: pouches, bleeds, leather samples, porous wood, complete pianos before and after restoration, etc., etc. If any one is interested I could provide further technical details. This is probably not the time to do it.
New unsealed pouch 25 cubic inches per minute
Stack valve lower seat 15 "
Piano reservoir 500 "
Piano stack 1000 "
Leaky foot pump piano 20,000 "
I am absolutely convinced of the value of quantitative measurement. Any comments?
[ I'm in absolute agreement with you, Philip. Could you begin by
[ telling us how to measure the airflow of bleeds and small hoses,
[ for example? Can your technique be used over a wide range of
[ pressure? Can it measure in-line airflow? Please tell us more.
[ -- Robbie
(Message sent Wed 5 Feb 1997, 06:47:23 GMT, from time zone GMT-0800.)