How should globe valves be installed in relation to pressure?

Globe valves are designed primarily for throttling and controlling the flow of fluid within a system. When considering their installation in relation to pressure, it's crucial to maintain optimal performance and prevent issues like chattering or damage to the valve.

Installing a globe valve with pressure below the seat is the appropriate application because this orientation provides the necessary sealing action and stability during operation. In this position, when the valve is closed, the pressure forces the valve disc down onto the seat, which helps create a strong seal. This configuration also prevents potential leakage and allows for better flow regulation when the valve is partially opened.

Furthermore, having pressure above the seat could lead to undesirable flow characteristics and may cause the valve to be less effective in controlling the flow. It can also increase the risk of the valve being forced open inadvertently if there is a sudden pressure change. Therefore, positioning the globe valve with the pressure below the seat ensures effective sealing and enhances operational reliability, making it the preferred practice for installation in a refrigeration and air conditioning system.