Process and Control Valves

What is the function of a fluid valve?

A fluid valve is used to regulate fluid flow within a hydraulic circuit or system to close a line or redirect pressure to a specific portion of the hydraulic circuit. A fluid valve controls the flow rate by regulating the speed of motors and cylinders. The actuator within a fluid valve allows for the control of the pressure within the hydraulic circuit by controlling the force and accounting for the length of the circuit. The most common fluid valves are ball, diaphragm, needle, and butterfly.

• Ball valves: Ball valves are most applicable in low-flow situations and consist of a metal ball with a hole in its center. Ball valves can open and close immediately and are considered more effective at forming a tight seal.
• Diaphragm valves: Diaphragm valves are often used in food, pharmaceutical, corrosive, and (waste)water applications. Diaphragm valves are designed with a valve body with two or more ports, an elastomeric diaphragm, and a seat to close the valve.
• Needle valves: Needle valves influence flow rates by an adjustable cross-section with a throttle spindle to manually actuate flow.
• Butterfly valves: Butterfly valves use rotary motion to open up and shut off hydraulic systems to regulate flow.

How to select the right valve

Selecting the right process control valve is crucial to ensure that a valve is the most cost-effective and suitable for your application. To figure out the best valve for your industrial fluid system, some essential elements should be considered, such as the size of the valve, the temperature conditions, and the pressure conditions under which the valve will be operating.

The size of a valve determines the capacity of processible flow; this needs to be aligned with the flow rates of the system. The size and geometry of the valve's flow path ultimately determine the flow capacity; depending on the flow capacity required, the size of the valve components should be adjusted.

Another critical factor to consider when selecting the right valve for your industrial fluid system is the temperature of the fluid handling system and the temperature of the environment wherein the system operates. Sealing materials expand and contract when the temperature fluctuates, so selecting a valve consisting of the most suitable materials is crucial.

A third factor to consider is the pressure the valve needs to hold and operate under. To select the right valve, the system's normal operating pressure, as well as the valve's maximum pressure limit, should be considered.