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AMETEK pneumatic testers are self-regulating, primary type
pressure standards.
An accurate calibrating pressure is produced
by bringing into equilibrium the pneumatic pressure on the
underside of a ball of known area by weights of known mass on
the top. The precision ceramic ball is floated within a tapered
stainless steel nozzle. A flow regulator introduces pressure
under the ball, lifting it in the tapered annulus until equilibrium
is reached. At this point the ball is floating and the vented
flow is equal to the fixed flow from the supply regulator. The
pressure, which is also the output pressure, is proportional
to the weight load. During operation the ball is centered by
a dynamic film of air, eliminating physical contact between
the ball and the nozzle.
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