The
clearance between the cylinder wall and piston skirt. By decreasing
the convolution width, higher working pressures may be achieved.
Generally, the convolution width should measure at least four
times the diaphragm's sidewall thickness.
Cylinder
Diameter (Bore)
The inside
diameter of the cylinder into which the diaphragm will fit and
by which the outside diameter of the convolution will be supported.
Cylinder Radius
The blend
radius between the cylinder wall and the flange.
Piston Cap
A plate which
attaches to the piston, sandwiching the piston area of the diaphragm
insuring the diaphragm stays in convolution.
Piston Diameter
Diameter of
the piston measured across piston head, including radius.
Piston Radius
The blending
radius between the piston head and the piston skirt.
Piston Skirt
The sidewall
area of the piston which supports the inside diameter of the
convolution.
Diaphragm
Cylinder Diameter
The diameter
across the diaphragm between the tangent points of the sidewall
and cylinder radius.
Fabric Side
Surface of
single coat diaphragm where fabric is visible. Always on low
pressure side, generally on outside of diaphragm.
Height
The height
of top hat and preconvoluted diaphragm is measured from the
bottom of the flange to the top of the head or convolution.
Piston Diameter
The diameter
across the diaphragm between the tangent points of the sidewall
and piston radius. Measured on the fabric or low pressure side
of the diaphragm.
Preconvoluted
A diaphragm
which has its convolution molded in. No hand forming is necessary
before installation.
Sidewall
That area
of the diaphragm between the flange and piston areas.
Top Hat
A diaphragm
molded in standard "hat" shape that must be formed
into convolution before installation.
Function
Bleedthrough
A defect in
a diaphragm caused during manufacturing where the fabric is
pulled through the rubber to the high pressure side of the diaphragm.
When pressure is put on the diaphragm, the rubber will be blown
away from the fabric and rupture.
Blowthrough
This occurs
when the pressure on the diaphragm reaches a level high enough
to blow a piece of the rubber through the threads of the fabric,
causing a leak. This is the result of selecting a weave of fabric
that is too open for the diaphragm's thickness.
Double Coat
This is a
type of diaphragm construction where the fabric is inserted
between two layers of rubber.
Effective Pressure Area
The area of
the diaphragm inside an imaginary circle to the convolution
midpoint on which the pressure introduced is transmitted to
the opposite side of the diaphragm.
Overstroke
Exceeding
the designed stroke of the diaphragm causing it to come out
of convolution. This can be avoided by designing mechanical
stops into your hardware.
Reverse Pressure
When the pressure
on the low pressure side of the diaphragm exceeds the pressure
on the high pressure side of the diaphragm. This will cause
the convolution to collapse and wrinkle. This wrinkle will cause
scrubbing and lead to premature failure.
Single Coat
This is a
type of diaphragm construction where there is rubber in the
high pressure side and fabric on the low presure side.
Spring Rate
This refers
to the forces caused by the rubber trying to return to its as-molded
position. This is generally found only in preconvoluted and
dish-shaped diaphragms.
Strikethrough
This refers
to the amount of rubber that comes through the fabric to either
fully or partially encapsulate the fabric during manufacturing.
