Goulds Pumps XHD - IOM - Manual (Page 40)

Installation
Check Explanation/comment Checked
Check that a check valve is installed in The location between the isolation valve and the
the discharge line, between the isola-
pump allows inspection of the check valve.
tion valve and the pump discharge The check valve prevents damage to the pump and
outlet. 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.
See Example: Discharge piping equipment for
illustrations.
If increasers are used, check that they See Example: Discharge piping equipment for
are installed between the pump and
illustrations.
the check valve.
If quick-closing valves are installed in
This protects the pump from surges and water
the system, check that cushioning de- hammer.
vices are used.
Example: Discharge piping equipment
Correct Incorrect
1. Check valve (incorrect position)
1. Bypass line
2. The isolation valve should not be positioned
2. Shut-off valve
between the check valve and the pump.
3. Check valve
4. Discharge isolation valve
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 (minimum-flow orifice) is not possible.
38 XHD Installation, Operation, and Maintenance Manual