All with Three screw pump A safety valve (pressure relief valve) is required at the pump outlet in all systems of. IMO AB's standard low-pressure series products are equipped with built-in safety valves to protect the pump during overpressure operation.

However, this built-in safety valve can only protect the pump against temporary overpressure. It can neither be used as a system pressure control device nor as a flow regulating device. Under the pump overpressure condition, the built-in safety valve will open, and the temperature will rise when the fluid flows back through the safety valve and circulates in the pump body. The range of temperature rise is in direct proportion to the set pressure of the safety valve and the return fluid percentage.

In addition to pumping low viscosity fluid, the pump can operate for a long time under the condition of up to 50% reflux without causing any damage. If the pump is expected to work under the condition of more than 50% reflux, it is necessary to explain to the technicians of Shanghai Kunjin Electromechanical Co., Ltd. in particular, so that the valve can be designed accurately by closely monitoring the pump body temperature according to this specific condition.

When the flow is less than 50 m3/h, if the fluid viscosity and temperature are within the allowable range of the pump, the maximum time that the pump can work under 100% reflux condition shall not exceed 3 minutes. When the flow is greater than 50 m3/h, the pump can only allow 100% backflow for 30 seconds. When the safety valve is opened, the noise will increase. This can also determine whether the system has overpressure.

If there is an independent safety valve at the pump outlet, its setting value should be high enough not to interfere with the built-in safety valve of the pump. When two pumps operate in parallel, the setting of safety valve shall also avoid mutual interference.

When adjusting the set pressure of the safety valve:

L Turn the safety valve clockwise to the maximum;

L Adjust the valve on the pipeline behind the pump until the required pressure value;

L Turn the safety valve counterclockwise until the pressure gauge indicates that the pressure will drop;

L Fully open the valve on the pipeline behind the pump

It is recommended that the set pressure of the safety valve be 1 bar higher than the normal operating pressure of the system

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