How are the pressure and flow rate of a high-pressure reciprocating pump adjusted?

In my opinion, flow regulation can be achieved by varying the frequency of the motor in order to reduce its speed； To adjust pressure, the opening force of the outlet check valve needs to be modified.

There is a method called: manual adjustment of the 0–100% stepless plunger stroke

Reciprocating pumps have an adjustment handwheel to control the stroke

1. For pumps equipped with motors and frequency converters, flow rate and pressure are adjusted by controlling the speed. 2. In cases where there is a control valve at the pump outlet, flow rate and pressure are regulated by adjusting the opening degree of this valve. 3. When there is no control valve at the pump outlet but there is a return line, the valve should be fully opened before starting the pump, after which it can be gradually closed to adjust flow rate and pressure. 4. For pumps without a control valve at the outlet, bypass regulation is commonly used; a bypass control valve can be installed for such adjustments. Typically, there are 2 pumps, one in operation and one as a backup. Each pump has a return line, which is used for starting and stopping the pump. There is also a return line on the main outlet pipeline of the two pumps; this line is used to regulate the flow rate, and it is equipped with a throttle orifice plate. This orifice plate serves two purposes: one is to reduce noise and vibration. Secondly: it prevents high-pressure substances from returning through this line to the pump inlet buffer tank, thereby avoiding pressure buildup; the safety valve then steps in to release pressure in time, thus serving a protective role.