INOXPA HLR, Installation, Service And Maintenance Instructions

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12 4.Installation (A) 2021/11
4.7. PRESSURE RELIEF VALVE
The positive displacement lobe pumps must be protected from excess pressure when they are
operating. Consequently, all the HLR pumps can be fitted with a stainless steel pressure relief valve
or a pressure by-pass
4.7.1. Protection
This valve protects the pump and prevents excessively high pressure arising in the circuit. It reduces the differential pressure
(
 p) between suction and discharge, but not the maximum pressure within the plant.
Do not use the pressure relief valve to protect the system from excess pressure. It is designed to
protect the pump only as it is not a safety outlet.
4.7.2. Operation principle
The pressure by-pass valve is located in the rotor case and prevents excess pressure arising inside the pump. For example,
when the pump's discharge port is clogged and the liquid cannot be pumped out, too high a pressure can cause serious
damage to some of the pump's parts. The pressure relief valve opens a passage from the pump's discharge side to its suction
side: an escape route, redirecting the flow again to the suction side whenever specifically high pressure levels are reached. The
by-pass is effective in both directions of rotation (only front cover assembly).
If the relief valve operates, this will mean that the equipment is not working properly. The pump
should be disconnected immediately. Identify and solve the problem before re-starting the pump.
Remember that the pressure relief valve is not able to be used to regulate the flow rate.
The pressure relief valve can be adjusted to any determined pressure, according to the type of pump being used.
4.8. ELECTRICAL INSTALLATION
Leave the connecting of the electrical motors to qualified personnel. Take the necessary measures to
prevent any breakdowns in the connections and wires.
The electrical equipment, the terminals and the components of the control systems may still carry an
electric charge even when disconnected. Contact with them may put the safety of operators at risk,
or cause irreparable damage to the material.
Before manoeuvring the pump, make sure that the electric box is switched off.
• Connect the motor in accordance with the instructions supplied by the manufacturer of the same.
• Check the direction of the rotation (see the signalling label on the pump).
• Start the pump motor briefly. Make sure the pumping direction is the right one. If the pump operates in the wrong
direction it may cause severe damage.
Pumps size 1, 2, 3, and 4 Pumps size 0
Check ALWAYS the direction of the motor’s rotation with liquid inside the pump.
For the models with sealing chamber, make sure always that it is filled of liquid before checking the
rotating direction.