1. Pump Discharge Pressure

The discharge pressure of a deep well vertical turbine pump refers to the total pressure energy (unit: MPa) of the liquid being sent after passing through the water pump. It is an important indicator of whether the pump can complete the task of transporting liquid. The discharge pressure of the water pump may affect whether the user's production can proceed normally. Therefore, the discharge pressure of the water pump is designed and determined based on the needs of the actual process.

Based on the needs of the production process and the requirements of the manufacturing plant, the discharge pressure mainly has the following expression methods.

1.Normal operating pressure: The required pump discharge pressure when the enterprise operates under normal working conditions.

2.Maximum required discharge pressure: When the enterprise's production conditions change, the working conditions that may occur depend on the required pump discharge pressure.

3.Rated discharge pressure: The discharge pressure specified and guaranteed to be achieved by the pump manufacturer. Rated discharge pressure should be equal to or greater than normal operating pressure. For vane pumps it should be the discharge pressure at maximum flow.

4. Maximum allowable discharge pressure: The maximum allowable discharge pressure value of the pump is determined by the pump manufacturer based on the pump's performance, structural strength, prime mover power, etc. The maximum allowable discharge pressure value should be greater than or equal to the maximum required discharge pressure, but should be lower than the maximum allowable working pressure of the pump's pressure components.

2.  Pump head H

The head of a water pump refers to the energy gained by unit weight of liquid passing through the deep well vertical turbine pump. Expressed by H, the unit is m, which is the height of the liquid column of the discharged liquid.

The effective energy obtained after unit pressure of liquid passes through the pump, also known as the total head or full head. We can also talk about the energy difference between the liquid at the outlet and the inlet of the water pump. But it must be noted: it is only related to the performance of the pump itself and has nothing to do with the inlet and outlet pipelines. The unit of lift is N·m or m liquid column height.

For high-pressure pumps, the pressure difference between the pump outlet and inlet (p2-P1) is sometimes approximated to represent the size of the lift. At this time, the lift H can be expressed as:

In the formula, P1——the outlet pressure of the pump, Pa;

P2 is the inlet pressure of the pump, Pa;

p——liquid density, kg/m3;

g——gravitational acceleration, m/S2.

Lift is a key performance parameter of a water pump, which is based on the needs of petroleum and chemical processes and the requirements of the pump manufacturer.

1. Normal operating head: The pump head determined by the discharge pressure and suction pressure of the pump under normal production conditions of the enterprise.

2. The maximum required lift is the lift of the pump when the maximum required discharge pressure (the suction pressure remains unchanged) changes when the enterprise's production conditions change.

3. Rated head The rated head is the head of the water pump under the rated impeller diameter, rated speed, rated suction and discharge pressure. It is the head determined and guaranteed by the pump manufacturer, and this head value should be equal to or greater than the normal operating head. Generally, its value is equal to the maximum required lift.

4. Closing head The closing head is the head when the flow rate of the water pump is zero. It is the maximum limit lift of the water pump. Generally, the discharge pressure under this lift determines the maximum allowable working pressure of pressure components such as the pump body.