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Back
Pressure
The static pressure existing at the outlet of a bursting disc
device at the time the device bursts or vents. Where pressure
is below atmospheric pressure, this can be termed Vacuum Pressure.
Back Pressure Support
Component of a bursting disc device which prevents failure of
the bursting 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 bursting discs made as a single group to the same
Specifications and from the same lot of material.
Bursting 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 bursting disc device.
Bursting Disc Assembly
The complete assembly of components which are installed into
the holder to perform the desired function.
Bursting Disc Device
A non-reclosing pressure relief device actuated by differential
pressure and designed to function by the bursting or venting
of the bursting disc(s). It is the complete assembly of installed
components, including where appropriate the bursting disc holder.
Bursting Disc Holder
The part of a bursting disc device which ensures the proper
performance of the bursting disc and accommodates its installation
into a system.
Bursting Pressure
The value of the pressure differential across the bursting disc
at which a bursting disc functions.
Coating
A layer of metallic or non-metallic material applied to components
of a bursting disc device (not a liner)
Coincident Temperature (Burst Temperature)
The temperature used in conjunction with a bursting pressure.
Conventional (Forward Acting) Bursting Disc
A bursting 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 bursting disc may be flat or
domed. A conventional domed bursting disc is domed in the direction
of the bursting pressure (ie where the bursting pressure is
applied to the concave side of the bursting disc).
Discharge Capacity
The rate at which a bursting disc device discharges a fluid
after bursting or venting of the bursting disc assembly.
Foil
The sheet or strip used for the manufacture of metallic bursting
discs.
Free-Flow (Discharge) Area
The area which is the minimum cross-sectional flow area of the
bursting disc device taking into consideration the possible
reduction of area by back pressure supports, catching devices
and parts of the bursting disc which remain after bursting or
venting.
Liner
An additional sheet or sheets of material forming part of the
bursting disc assembly or holder (not a coating)
Manufacturing Range
Range of pressure within which the average bursting pressure
of a batch of bursting 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. This is also known as Maximum Operating
Pressure to Burst Pressure Ratio.
Operating Pressure (Working Pressure)
The pressure which the bursting disc is exposed to during normal
operation
Operating Temperature (Working Temperature)
The nominal temperature which the bursting 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 pressurised
system (can differ from burst pressure).
Relieving Temperature
The maximum temperature under discharge conditions in the pressurised
system (can differ from burst temperature).
Reverse Acting (Buckling) Bursting Disc
A bursting disc which is domed against the direction of the
bursting pressure ie where the bursting pressure is applied
to the convex side of the bursting disc and designed to fail
under compression by buckling, bending or shearing forces.
Slotted Lined (Composite) Bursting Disc
A conventional bursting 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 bursting 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 burst disc performance or requirement.
May be specified as a minimum or maximum value.
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