Check
Explanation/comment
Checked
Make sure that the suction piping is free
from air pockets.
This helps to prevent the occurrence of air and cavita-
tion in the pump inlet.
Check that the piping is level or slopes
downward from the liquid source.
—
Make sure that no part of the suction pip-
ing extends below the suction flange of the
pump.
—
Make sure that the suction piping is ade-
quately submerged below the surface of
the liquid source.
This prevents air from entering the pump through a
suction vortex.
4.6.3 Discharge piping checklist
Checklist
Check
Explanation/comment
Checked
Check that an isolation valve is installed in
the discharge line. For specific gravity less
than 0.60, minimize distance from pump
discharge.
The isolation valve is required for:
•
Priming
•
Regulation of flow
•
Inspection and maintenance of the pump
•
Reduce risk of pumpage vaporization and vapor
locking at low flow rates for low specific gravity liq-
uids.
Check that a is installed in the discharge
line, between the isolation valve and the
pump discharge outlet.
The location between the isolation valve and the pump
allows inspection of the check valve.
The check valve prevents damage to the pump and seal
due to the back flow through the pump, when the drive
unit is shut off. It is also used to restrain the liquid flow.
If increasers are used, check that they are
installed between the pump and the check
valve.
—
If quick-closing valves are installed in the
system, check that cushioning devices are
used.
This protects the pump from surges and water hammer.
4.6.4 Bypass-piping considerations
When to use a bypass line
Provide a bypass line for systems that require operation at reduced flows for prolonged periods. Connect
a bypass line from the discharge side (before any valves) to the source of suction.
When to install a minimum-flow orifice
You can size and install a minimum-flow orifice in a bypass line in order to prevent bypassing excessive
flows. Consult your ITT representative for assistance in sizing a minimum-flow orifice.
When a minimum-flow orifice is unavailable
Consider an automatic recirculation control valve or solenoid-operated valve if a constant bypass (mini-
mum-flow orifice) is not possible.
4.6 Piping checklists
3640 i-FRAME API Type BB2 2-Stage / ISO 13709 2nd Ed. API 11th Ed. Installation, Operation, and Maintenance Man-
ual
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Содержание Goulds Pumps i-FRAME 3640
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