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MDE-4334C Atlas Start-up and Service Manual · April 2008
Hydraulic/Mechanical Components
Pumping Unit
3
Inspect the piping, fittings, and associated system equipment for leaks, noise, vibration and
overheating.
4
If possible, check the flow rate to ensure that the pump is operating within the expected
parameters. Record the flow rate.
Incorrect settings of the PRV can cause system component failure,
personal injury and property damage.
WARNING
5
Check the pressure setting of the PRV by momentarily closing a valve in the discharge line
and reading the pressure gauge. This pressure should be 10 - 20 psi (69 - 138 kPa) higher than
the maximum system operating pressure, or the external bypass valve setting (if equipped). Do
not operate the pump against a closed discharge valve for more than a minute.
Draining the Pump
To drain the pump, run the pump with the discharge valve open and intake valve closed.
Bleed air into the pump through the intake gauge plug hole or through a larger auxiliary fitting
in the intake piping. Pump air in 30 second intervals to clean out most of the pumpage.
Note: Some residual fluid will remain in the pump and piping.
Pump Relief Valve
Note: The pump internal relief valve is designed to protect the pump from excessive pressure
and must not be used as a system PCV.
Pumping volatile liquids under suction lift may cause cavitation. Partial closing of the
discharge valve will result in internal relief valve chatter and is not recommended. For these
applications, install an external system PCV and necessary bypass piping back to the storage
tank.
A system PCV is also recommended while operating for extended periods (more than a
minute) against a closed discharge valve.