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Testing Valve Facing Materials


Sealing the edge of a valve facing


assembling the Standard secondary valve


Hi John,

Your valve terminology article is good. An inside valve, and outside valve, the top, the bottom-- all as ambiguous as you can get. It's like calling a lift an elevator. Nobody could ever get back down, since they only go up.

That said, 3-4 decades ago I was calling primary valves "non-inverting valves, and secondary valves inverting valves." Then I defined it-- when the input (air) is the same as the output (air) that's a non-inverting valve. Air-in, vac out is an "inverting valve." All valves are outside valves. All valves are inside valves. When an "inside valve" is "closed," half of it is on the outside. It's in the room atmosphere, right? So that's "outside," too. Outside valves? Most of an "outside valve" is inside, not outside. Right?

When we call them inverting and non-inverting valves, one valve isn't being defined by the other one. But when we call a non-inverting valve an "outside valve"-- which is 90% inside anyway, then it is relative to something else and not descriptive of itself. A "primary valve" is relative to a secondary valve but not only that, it REQUIRES the secondary valve in order to be called "primary." And when a secondary valve is used alone it's no longer "secondary." It's "primary." So you can also hit them with this, too.


Valve Facing Terminologies by John A Tuttle 2/26/2018

Web form http:www.mmdigest.com/Contact submitted from, tracking # 10595

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Hi All,

With all of the work I'm doing with valve facing materials, I've also been doing a lot of reading. One thing that puzzles me somewhat are the various terminologies I've found. There's 'the vacuum side' and 'the atmosphere side'. There's the 'upper' and the 'lower'. And, there's the 'top' and the 'bottom'.

Personally, I've always referred to the facings as 'intake' and 'exhaust'. My thinking is simple; 'intake' lets the good stuff 'in' and 'exhaust' lets the bad stuff 'out'. The good stuff is the vacuum. The bad stuff is the atmosphere.

Now I realize that you don't actually 'let vacuum in' or 'let atmosphere out'. In every case, the atmosphere is always trying to equalize the negative air pressure. Not the other way around. I'm reminded of something someone said: If a window gets shot out of an airplane at 35,000 ft, things don't get sucked out of the airplane. They get blown out by the comparatively positive pressure inside the plane. And as soon as the pressures equalize -well, you die in less than 30 seconds unless you're really, really lucky.... but that's a whole other story. But I digress...

What I'm really looking for is an explanation for the terms 'upper' and 'lower' or 'top' and 'bottom'. The reason I'm asking is because quite a large number of player systems have horizontally inclined valves. So, there is no 'upper', 'lower', 'top', or 'bottom'. And, if 'upper' and 'top' refer to the atmosphere side and 'lower' and 'bottom' refer to the vacuum side, where is that explained so a novice can find it?

BTW, if this seems like a dumb question, I would remind you that Carl Sagan, in his work 'The Demon-Haunted World: Science as a Candle in the Dark' said: "There are naive questions, tedious questions, ill-phrased questions, questions put after inadequate self-criticism. But every question is a cry to understand the world. There is no such thing as a dumb question".

Musically, John A Tuttle
Brick, NJ, USA

I'm still in the process of compiling some of the various videos I made during the time that I've been working to find a good valve facing leather for the Standard and Autopiano systems. A few of them are below.

The main thing I discovered is that the seal occurs where the valve leather meets the stem. I just found one of the first set of videos I shot about Standard Valve Leakage that shows beyond any doubt that the leakage is occurring where the leather meets the stem. So, I started searching for a leather that would make a good seal at the stem. This led me on a long journey through a dozen different commercially available leathers and other materials; none of which worked to my satisfaction. Then I thought of the novel idea of using a leather that was right in front of me all the time, i.e., flap valve leather. It has two properties that all of the others lacked. One, a solid epidermis layer to create the seal at the stem. Two, a very flat smooth surface to create the seal at the valve plate. The videos below show some of the work I've done to arrive at the conclusion of what to use for the intake facing. One thing that's not clearly mentioned is that the hole in the center of the facing is 0.020" smaller than the stem. This is critical to making the seal.

Standard Valve - Sealing the felt


Standard Valve Wobble


Testing Valve Facing Materials


Assembling the Standard secondary valve


Questions? Write to Me! ( John A Tuttle)

This page was last revised on October 14, 2020 by John A Tuttle.

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