Terry McGee Posted May 29, 2014 Share Posted May 29, 2014 I'll give the old "suck test" a go first, and thank you very much for the offer. No worries. The suck test should be fine as a go/no-go test - it's a bit harder to be quantitative about. You could try sucking on a piece of tube with the fabric clamped over the far end. You'll soon know if you can pull a vacuum - the tube will stick to your lips. Under this sort of test, the length of time the tube sticks to your lips becomes the quantitative value. I imagine though you'll have trouble sealing the folds of the fabric where it wraps around the tube. A cruel reminder that the best material in the world won't help if your construction isn't sound! On the plus side, the suck test actually tests at a pressure much higher than bellows pressure. Human lungs can get up to about 1psi (700mm of water) - more if you are a trained blower, eg glassblower, bagpiper, trumpet player, or are in the business of siphoning petrol out of cars. Chris Ghent and I did tests which suggest bellows only get up to 140mm of water (playing "really loud") or 200mm compressing really hard with no buttons pressed. Not what either of us expected! "And the fourth little piggy built his house out of concertina reeds, and, when the Big Bad Wolf came along, he huffed, and he puffed, and...... played quite a merry little tune." Terry Quote Link to comment Share on other sites More sharing options...
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