How do you design a control valve?
Valve Design Equation
- The valve design equation relates the pressure drop ΔPv Δ P v across the valve to the volumetric flow rate q .
- The Cv is a measure of the size of a valve and valve suppliers have different valve body sizes, each with a different Cv value.
What is xT in control valve sizing?
For compressible fluids, a terminal pressure drop ratio, xT, similarly describes the choked pressure drop for a specific valve. When sizing a control valve, the smaller of the actual pressure drop or the choked pressure drop is always used to determine the correct Cv.
How do you choose a control valve?
Valve characteristics selection guidelines
- Type of fluid to be controlled.
- Temperature range of fluid.
- Viscosity range of fluid.
- Specific gravity range of fluid.
- Minimum and maximum flow required.
- Minimum and maximum inlet pressure at the control valve.
- Minimum and maximum outlet pressure at the control valve.
What is control valve sizing?
The process of “control valve sizing” is a procedure where the dynamics of the system are matched to the performance characteristics of the valve. This produces a control valve of an appropriate size and type that will best meet the needs of managing flow within the process system.
What is port size of control valve?
Port size is the size of the opening that fluid can travel through when the ball valve is in the open position.
What is Cv in valve sizing?
Valve Flow Coefficient (Cv) is the flow capability of a control valve at fully open conditions relative to the pressure drop across the valve. It is defined as the volume of water (GPM in the US) at 60°F that will flow through a fully open valve with a pressure differential of 1 psi across the valve.
What is valve Kv?
The Kv value expresses the amount of flow in a regulating valve at a given valve position with a pressure loss of 1 bar. The Kvs value expresses the amount of flow in a regulating valve at a fully-open valve position and a pressure differential of 1 bar.
What are the components of a control valve?
Basic Parts of Control Valves. Regardless of type, all valves have the following basic parts: the body, bonnet, trim (internal elements), actuator, and packing. The basic parts of a valve are illustrated in Figure 1. Control Valves mainly have Two parts: 1) Actuator Part. 2) Body Part for easy understanding.
How do you calculate the CV of a valve?
For example a valve with a Cv of 10 will flow 10 GPM with a 1 psi pressure drop. The formula used to select the valve Cv with the specified differential pressure is: Cv=GPM/ ( (SQ RT (∆P)). If the specified ∆P is 4 psid and full flow is 10 GPM the calculated CV is 10/SQ RT of 4 = 5.
What is a high pressure control valve?
The QB3H (electronically controlled) high pressure valve was originally designed for laser cutting with Argon , Nitrogen, Oxygen and air. The QB3H continues to be very successful in this application, but it is now used across multiple industries and processes to control high pressure with high flows in compact spaces.
What is a control valve orifice?
An orifice valve is a flow control valve that is used to restrict or control the fluid flow . An orifice is a small opening or hole in a plate or pipe or body. When the fluid passes through the orifice, the fluid flow gets restricted. An orifice valve usually finds its application in areas where custody transfer has to take place from one party to other party.