A Brief on Globe Valves, Float Valves, and Their Working

A Brief on Globe Valves, Float Valves, and Their Working

A Globe valve is also called a stop valve as it is a forced sealing valve. When the valve is closed, to prevent the sealing surface from leaking, pressure is applied to the disc. An operating force overcomes the resistance when a medium enters the valve from the bottom of the valve. This operating force is the friction between the packing and the valve rod and the thrust induced by the pressure of the medium. Since the force to seal the valve is higher than the force to open the valve, the diameter of the rod is kept large to prevent the valve rod from getting bent.

There are three types of connection modes: flange connection, welding connection and screw connection. When the self-sealing valve appears, the flow of the medium of the globe valve is re-directed from the top of the valve disc to the valve chamber. The force to close the valve is small under medium pressure. Whereas when there is a large force to open the valve, the diameter of the valve rod can be simultaneously reduced.

When the flow has achieved its maximum limits, it indicates that the valve has reached the fully open position, which is determined by the stroke of the disc.

What are the Advantages of Globe Valve?

Globe valves have a number of advantages.

·         These valves have a simple structure.

·         It is easy to manufacture and maintain these valves.

·         It has a short closing and opening time and a small working stroke.

·         It has a long service life and good sealing performance.

·         The sealing surfaces have less friction between them.

Float Valves and how they work

Float valves, or ballcocks, are completely mechanical level control systems that are commonly used to regulate the levels of fluids in a tank or a cistern. It prevents overflow or overfilling by connecting to the incoming liquid using a valve connector. A large number of small float valves are used in domestic systems. The float plays an important role in detecting changes in the elevation of the liquid and allows the valve to open or close accordingly. This valve maintains the cold-water level in a header tank to regulate the pressure of the hot water system.

A float valve generally has a roughly spherically shaped hollow ball attached through a lever or arm. This ball rides on or beneath the liquid surface level. Its upward and downward motions get mechanically transferred to the valve, making it open or close depending on its position on the liquid surface.

What are the Advantages of Float Valves?

·       These valves do not require to be monitored or controlled. The liquid level regulation is automatic.

·        A float valve prevents overflow or over-filling as the water stops once the desired level is reached

·       Float valves are highly economical as no electrical power is required for their functioning. Hence, it is apt for tank level control in remote areas where there is no or scarce availability of electrical supply.