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Backpressure
The static pressure existing at the outlet of a rupture disc
device at the time the device bursts or vents. Where pressure
is below atmospheric pressure, this can be termed Vacuum Pressure.
Backpressure Support
Component of a rupture disc device that prevents failure of
the rupture disc due to pressure differential in a reverse direction.
Where system pressure is below atmospheric pressure, this can
be known as a Vacuum Support.
Batch
A quantity of rupture discs made as a single group to the same
specification and from the same lot of material.
Bursting disc (See Rupture Disc)
Alternate name for rupture disc, used primarily in Europe
Bursting Pressure
The value of the pressure differential across the rupture disc
at which a rupture disc functions.
Coating
A layer of metallic or non-metallic material applied to components
of a rupture disc device (not a liner)
Coincident Temperature (Burst
Temperature)
The temperature used in conjunction with a bursting pressure.
Conventional (Forward Acting)
Rupture Disc
A rupture disc designed to fail when a build up of pressure
in the system exceeds the tensile strength of the disc material
(tension loaded). A conventional rupture disc may be flat or
domed. A conventional domed rupture disc is domed in the direction
of the bursting pressure (i.e. where the bursting pressure is
applied to the concave side of the rupture disc).
Discharge Capacity
The rate at which a rupture disc device discharges a fluid after
bursting or venting of the rupture disc assembly.
Foil
The sheet or strip used for the manufacture of metallic rupture
discs.
Free-Flow (Discharge) Area
The area which is the minimum cross-sectional flow area of the
rupture disc device taking into consideration the possible reduction
of area by back pressure supports, catching devices and parts
of the rupture disc which remain after bursting or venting.
Liner
An additional sheet or sheets of material forming part of the
rupture disc assembly or holder. (not a coating)
Manufacturing Range
Range of pressure within which the average bursting pressure
of a batch of rupture discs shall fall in order to be acceptable
for a particular application as agreed between manufacturer
and customer.
Maximum Operating Pressure
This is the maximum system pressure to which the disc may be
exposed without causing premature metal fatigue to the rupture
disc. Maximum operating pressures are typically between 50%
and 100% of the rated burst pressure of the disc, depending
on the type of disc. (Also known as Maximum Operating Pressure
to Burst Pressure Ratio)
Operating Pressure (Working Pressure)
The pressure that the rupture disc is exposed to during normal
operation.
Operating Temperature (Working
Temperature)
The nominal temperature that the rupture disc is exposed to
during normal operation.
Performance Tolerance
The difference between the maximum and minimum specified bursting
pressures at a coincident temperature. “Burst tolerance"
is the allowable deviation in actual burst pressure from the
"marked burst pressure". Typically expressed as a
percentage (or in "psig"), a disc properly specified
and installed should always burst within the "tolerance"
for the particular type, style, and rated pressure of the disc.
Relieving Pressure
The maximum pressure under discharge conditions in the pressurized
system. (Can differ from burst pressure)
Relieving Temperature
The maximum temperature under discharge conditions in the pressurized
system. (Can differ from burst temperature)
Reverse Acting (Buckling) Rupture
Disc
A rupture disc which is domed against the direction of the bursting
pressure i.e. where the bursting pressure is applied to the
convex side of the rupture disc and designed to fail under compression
by buckling, bending or shearing forces.
Rupture Disc
A non-reclosing element designed to burst or rupture at a predetermined
pressure to protect systems or individual plant from unacceptable
levels of pressure or vacuum; the pressure containing and pressure
sensitive component of a rupture disc device.
Rupture Disc Assembly
The complete assembly of components that are installed into
the holder to perform the desired function.
Rupture Disc Device
A non-reclosing pressure relief device actuated by differential
pressure and designed to function by the bursting or venting
of the rupture disc(s); it is the complete assembly of installed
components, including where appropriate the rupture disc holder.
Rupture Disc Holder
The part of a rupture disc device that ensures the proper performance
of the rupture disc and accommodates its installation into a
system.
Slotted Lined (Composite) Rupture
Disc
A conventional rupture disc made up of two or more layers, one
of which is slit or slotted so as to reduce its strength and
to control the bursting pressure of the rupture disc; may be
flat or domed.
Specified Burst Pressure|
The pressure quoted by the user or the manufacturer with a coincident
temperature when specifying the rupture disc performance or
requirement; may be specified as a minimum or maximum value.
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