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11.1.2.2 Overpressure safety device
A Watson‑Marlow pump operates by positive displacement. Should a blockage or restriction
occur, the pump will continue to operate until either of the following occur:
•
The pumphead tubing or element, or ancillary device may rupture, leak or otherwise fail
The fluid path pipework or ancillary device, may rupture, leak or otherwise fail
•
The drive fails
•
Install an overpressure safety device which can automatically activate in an overpressure event.
This device should:
•
As close as possible to the discharge pumphead port
Be able to be set to a pressure which is lower than the pressure rating of the system
•
•
Be able to stop the pump or divert the fluid to a safe location upon being triggered
Have a fail-safe feature
•
11.1.2.3 Isolation and drain valves
Isolation and drain valves must be installed in the fluid path in the following scenarios:
•
Where it is not practical to drain the entire fluid path during:
Pumphead tubing or element replacement
o
o
Where procedures require the pump to be removed from service, such as due to
a fault
The pump will act like a valve when stopped, preventing fluid from flowing through the
•
pumphead.
As the tubing, element, or pumphead wears, there can be flow through the
o
pumphead (which would be a normally closed fluid path). In applications where
unintentional flow through the pumphead, cannot be tolerated or would create
a hazard, then isolation valves must be installed
Valves must be opened before the pump operates and closed after the pump has stopped.
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