What valve is most commonly used to isolate a pump on the suction side?

The gate valve is the most commonly used valve to isolate a pump on the suction side due to its design that allows for minimal resistance to flow when fully opened. It has a simple mechanism that enables it to create a tight seal when closed, effectively stopping the flow of water. This characteristic is crucial when isolating a pump for maintenance or repair, as it prevents backflow and ensures that no water enters the system while the pump is taken offline.

In addition, gate valves are easy to operate with a simple turning motion, making them user-friendly for operators needing to quickly shut off flow. They are generally preferred for on/off service rather than for throttling or flow control, as they do not perform well in partially open positions where erosion can occur.

When considering the other types of valves, globe valves are designed primarily for throttling and controlling flow rather than full isolation. Check valves prevent backflow but do not isolate a pump since they allow flow in one direction and do not seal completely when closed. Needle valves, while useful for fine flow control, are not suitable for isolating larger systems due to their small size and flow restriction characteristics. Thus, the gate valve’s functionality aligns perfectly with the requirement for effective isolation on the suction side of a pump.