Issues with the installation of check valves

I think the function of the check valve at the pump outlet is to prevent the material from flowing back and causing the pump’s impeller to rotate in the reverse direction; therefore, whether the valve is installed at the top or bottom depends on the process requirements, and either position is acceptable

It is generally installed upstream of the shut-off valve.

There should be a difference: generally, the outlet valve is connected to the pump first, and then the check valve is connected. Since pumps usually have a backup unit, with one in use and one as a backup, the outlet valve of each pump is connected directly to the pump. The check valve, on the other hand, is installed on the common pipeline behind the outlet valves of both pumps; there is no need for two check valves. Additionally, the outlet side of the pump is in a high-pressure area, and the purpose of installing a check valve in the pipeline is to allow it to close promptly in case of an unexpected shutdown of the pump or sudden increases in pressure, thereby preventing backflow that could damage the impeller or cause other hazards. Thus, in the event of an accident, it is the check valve that bears the impact of high pressure from liquid hammer or sudden pressure spikes. Check valves generally have high pressure resistance and can handle such high-pressure impacts, whereas ordinary valves can only withstand the rated pressure specified at the time they were manufactured; they tend to get damaged under such high-pressure conditions. That’s why the outlet valve is connected to the pump first, followed by the check valve – this way, in the event of an accident, the check valve closes first, keeping the outlet valve in a low-pressure area and thus preventing damage to it due to high-pressure impacts from liquid hammer.

Generally, it is more common to install an independent check valve for each pump. At the pump outlet, a check valve is installed first, followed by a shut-off valve. If the check valve is placed behind the shut-off valve, it remains under pressure all the time, which is detrimental to its lifespan.

Agree with the person on floor 5; I work in a chemical plant, and what I’ve seen is that there is usually a separate check valve for each pump. Of course, an additional check valve is also installed on the important pipelines. Since it is one pump with one check valve, it is located below (upstream of) the shut-off valve

I don’t entirely agree with the view on floor 4. Especially when two pumps are connected in parallel, installing a check valve only at the common outlet of the two pumps can indeed prevent the material downstream from flowing back. But if one pump is shut down while another is running, and the outlet valve of the shut-down pump fails to close for some reason, the output from the other pump will flow back. Therefore, each pump should be equipped with a check valve separately, and it should be placed before the outlet shut-off valve. :)

The check valve is installed at the outlet of the pump, in front of the valve.

Why is the drain valve 20519 installed downstream of the check valve, whereas the process manual specifies it should be installed upstream of the check valve?

Generally, a check valve is connected first to the pump outlet and then a shut-off valve. If a shut-off valve is connected first and a check valve afterward, what should I do if the check valve fails and needs to be removed? What should be done with the material in the pipeline upstream of the check valve? Additionally, the pump inlet is also directly connected to the filter

Connect a check valve to the pump outlet first, and then a shut-off valve； If the pressure difference between the pump inlet and outlet is above 4.0 MPa, a double check valve must be installed. These are general design specifications

What everyone is saying makes sense; however, in many factories the check valve is indeed located downstream of the outlet valve, and it seems that this installation method has some issues

In many factories, the check valve is indeed located behind the outlet valve; the outlet pressure is 40 kilograms, and the flow rate is relatively low at 50 cubic meters. Please give me some advice, expert.

I would like to ask the person on the fifth floor: You mentioned in your text that \"if the check valve is installed behind the shut-off valve, it remains under pressure at all times, which is detrimental to its lifespan.\" Why is the check valve under pressure in such a situation? Is there a difference compared to having it in front of the shut-off valve?

A pump, a check valve, and a shut-off valve; the check valve is installed in front of the shut-off valve

When starting a large water pump, it’s necessary to close the outlet valve first to release air, and then gradually open the outlet valve. It might be related to this