ITT Goulds Pumps 3409, Инструкция по установке, эксплуатации и обслуживанию

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• When foot valves are used, or where there are other possibilities of water hammer, close the dis-
charge valve slowly before you shut down the pump.
Check valves
In normal applications, check valves are placed in the discharge piping. Before you use a check valve in
the suction piping, consider the added pressure drop to the pump, the potential of water hammer, and
the chance of allowing the entire pump volute to be exposed to the discharge pressure.
Gate valves
Where two or more pumps are connected to the same suction line, install gate valves so that any pump
can be isolated from the line.
Before you install gate valves, review these considerations:
• Always install gate valves on the suction side of the pumps with a positive pressure for mainte-
nance purposes.
• Always install gate valves with the stems in a horizontal position to avoid air pockets.
• Globe valves should not be used, particularly where NPSH is critical.
4.5.4 Discharge piping considerations
Before you construct discharge piping, review these considerations:
• If the discharge piping is short, then the pipe diameter can be the same as the discharge opening.
• If the piping is long, then the pipe diameter should be one or two sizes larger than the discharge
opening.
• On long horizontal runs, it is desirable to maintain the most even grade possible.
• Avoid high spots, such as loops. High spots will collect air and throttle the system or lead to erratic
pumping.
• A check valve and an isolating gate valve should be installed in the discharge line.
• The check valve is placed between the pump and the gate valve. This protects the pump from
excessive backpressure and prevents liquid from running back through the pump in case of
power failure.
• The gate valve is used for priming and starting and also shutting down the pump.
4.5.5 Pressure gauges
Install properly sized pressure gauges in both the suction and discharge nozzles in the gauge taps pro-
vided. The gauges enable the operator to observe the operation of the pump and to determine whether
the pump is operating in conformance with the performance curve. If cavitation, vapor binding, or other
unstable operations occur, then widely fluctuating discharge pressure will be noted.
4.6 Pump doweling
Pump units can be doweled on diagonally opposite feet. Do not do this until the unit has run for a suffi-
cient length of time and alignment is within the required alignment tolerance.
4.6 Pump doweling
Model 3409 Installation, Operation, and Maintenance Manual 31