The pressure gauge of the hydraulic system fluctuates greatly

A check valve needs to be added, as there is leakage at the back, which prevents pressure retention and leads to back-and-forth oscillations.

It depends on what you want to do – add a check valve? What do you mean by protecting the pressure gauge? Can that pressure gauge still measure the actual pressure? What’s the use of a pressure gauge? You’re putting the cart before the horse here. If the process involves pulsed pressure, then you just need to use a pressure gauge that can withstand shock – for example, those used with piston pumps, where the outlet is equipped with such a pressure gauge whose pointer moves back and forth. That’s exactly the purpose of a pressure gauge. If you’re worried that it might get damaged, you can simply remove it and block the opening instead.

By connecting the equipment of the subsequent piping to the outlet of the hydraulic pump, the problem with the jump in pressure will be alleviated. The reason for using a video skip table is the lack of backpressure at the output.

Our factory has also encountered severe oscillations in the pressure gauge at the outlet of the plunger pump. A damper was added between the pressure gauge and the pipeline; this is equivalent to installing a shut-off valve with a small diameter, which helps to minimize the amount of pulsating flow that reaches the spring steel part of the pressure gauge, thereby reducing the resulting deformation. It only reduces the fluctuations; it cannot eliminate them completely. If the adjustment is made too far, the pointer stops moving and the oscillations cease entirely, which means that the flow passage of the damper is completely closed, resulting in an inaccurate pressure reading. An optimal situation is one in which the amplitude of the pointer’s movement is between 1-2 cm. Furthermore, as long as a damper is installed to achieve shock absorption, the pressure gauge will not return to zero when the pressure in the pipeline is released, because there is a portion of the sealing medium that cannot flow through the damper under low pressure differences. Another type of pre-loaded diaphragm damper is more complicated to install than the one mentioned above; after it is installed on the piping system, nitrogen must be added to the sealed container to apply a preset pressure. Due to the compressible nature of gas, this can reduce the oscillations of the pressure gauge.

Is the check valve installed at the outlet of the pump?

Adding a damper yields better results

After watching your video: 1. It should be a plunger pump； 2. Simulating pump operation (with the outlet going directly back into the tank without any connected equipment) is likely the cause of this situation. The pressure at the outlet of a plunger pump is determined by the outlet equipment connected to it; for example, if the equipment can handle 2 MPa, then the pressure at the outlet will remain within the range of 2–3 MPa, rather than fluctuating between 0–3 MPa. This results in smaller fluctuations in pressure. Secondly, it’s common to use pressure gauges designed to withstand vibrations, in order to reduce the likelihood of damage to such gauges.

It seems to be a pulse volume pump; due to fluctuations in pipeline pressure, the pressure gauge is fine. However, there are two issues: 1) the installation location is incorrect, and 2) the selection is inappropriate (seismic-type gauge for filling with liquid). 3 Dampers need to be installed. It is recommended to remove it, as installing it now seems pointless. If necessary, I would like to reinstall it in a new location and add new fittings.