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Suction losses in a leaky pianola are very hard to estimate.  We have
to assume the machine is in good condition with no leaks.  The air
volume used for a note playing pneumatic is composed of two parts;
(1) one is the continuous air usage when the note is playing, and is
due to the air bleed, and (2) two is when the pneumatic actually closes.
While it is closed, it consumes no air.

The volume of air consumed by each pneumatic is calculated approximately
by the formula  Volume = L x W x inside span, where L is the outside
length of the pneumatic, W is the width, and inside span is the outside
span minus two wood thicknesses.

The total air volume removed also includes the volume of air in the
channels between the valve and the pneumatic.  In this respect, the
Simplex unit valve is the most efficient I've come across.

For the wind motor, the volume of each pneumatic is calculated in
the same way, but the total air volume increases with the motor speed.
So the air consumption is so many cubic inches per second.

The air consumption does not really depend on the vacuum level (or
loudness) except that the air bleed would consume more air.  The bleed
arrangement on the Ampico B uses a small amount of air compared to a
non-Ampico, and is again, a very efficient way of venting the pouch.

My paper in the MMD Archives may be of some help in understanding the
action of the pneumatics.

Regards from
Paul Rumpf
Melbourne, Australia

 [ See "Mechanical Forces Developed in Pianola Pneumatic
 [ Motors", by Paul Rumpf, November 2008, at
 [ http://www.mmdigest.com/Gallery/Tech/index.html  -- Robbie