What are the types of control valves?

What are the types of control valves?

List of common types of control valve

• Sliding Stem. Globe valve – Type of device for blocking or regulating the flow of fluids. Angle body valve. Angle seat piston valve.
• Rotary. Butterfly valve. Ball valve.
• Other. Pinch valve. Diaphragm valve.

How do you find the control valve on a CV?

Calculating control valve CV you must subtract the outlet pressure (P2) from the inlet pressure (P1) . This is a key element needed for the control valve sizing. The relation between flow rate and pressure drop is an easy concept.

How do you choose a control valve?

When selecting a control valve for process plant, there are many things to be considered. These can include the valve flow characteristic, size, valve body and trim materials, noise, potential for damage from cavitation or flashing, actuator type and size, dynamic response to changes in control signal etc.

How do you design a control valve?

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. The valve position or lift l is adjusted to regulate flow through the valve.

How do you calculate CV flow?

Control Valve Sizing

1. Control Valve Sizing.
2. When sizing a control valve, the most common approach is to calculate the flow coefficient, Cv which is a measure of the capacity of the valve body and trim.
3. C = Q/N1 * √ (ρ1/ρ0) / (∆P)
4. ρ1/ρ0 is the relative density.
5. Fluid Density: 965.4 kg/m3.
6. Flow Rate (Q): 360 m3/h.
7. C = Q/N1 * √ (ρ1/ρ0) / (∆P)

What is CV value?

The valve coefficient, Cv, is a number which represents the capability of a valve (or any flow component) to flow a fluid. By definition, a Cv value of one is the Cv required to flow one gallon per minute (gpm) of water at 60′ F with a pressure differential of one psi. Flow is proportional to the value of Cv.

How does CV affect flow?

The definition of Cv is based on water, which has a G (specific gravity) = 1.0. Fluids with other gravities will flow at different rates. For example, heavier fluids will have a greater pressure loss through the same valve passage. The viscosity of the fluid will also affect its flow rate through a valve.

What is a CV factor?

The Cv factor is the number of U.S. gallons per minute that will pass through a valve with a pressure drop of (1) psi.

What is rated CV and calculated CV?

Rated travel: the displacement of the closure member from the closed position to the designated full open position. Thus, rated Cv is Cv attained at full open position. In my opinion, calculated Cv is a Cv value calculated at particular conditions (P1, P2, flow rate, specific gravity etc.).

Is Valve CV dimensionless?

CV: The Flow Coefficient, CV, is a dimensionless value that relates to a valve’s flow capacity. Its most basic form is Q=Flow rate and ∆P=pressure drop across the valve.

How do I calculate valve size?

The volume flow rate for liquids can be calculated by multiplying the fluid velocity times the flow area. Thus, Cv is numerically equal to the number of U.S. gallons of water at 60°F that will flow through the valve in one minute when the pressure differential across the valve is one pound per square inch.

How many type of valve are there?

Examples of quarter-turn valves are ball valves, plug valves, and butterfly valves. There are 2 distinct types of linear valves: rising stem (multi-turn) and axial. While both valve types rely on the linear motion of the flow obstructer, they are very different in construction and operation.

How do you size a gas control valve?

Control Valve Sizing Rules Of Thumb

1. Set the design flow as the greater of:
2. Set the control pressure drop to equal 50% – 60% of the frictional pressure loss of the piping system.
3. Limit the maximum flow rate : minimum flow rate turndown to 5:1 for linear trim valves and 10:1 for equal percentage trim valves.

What is the symbol for a valve?

Valve Symbols for P&IDs. The generic symbol for a 2-way valve is two triangles pointing to each other with the tips of the inner points touching. The pipe lines are represented by lines connecting to each side of the valve symbol.

What is the purpose of a needle valve?

Needle valves, sometimes referred to as plunger valves, are regulating valves and enable engineers to finely control and regulate water flow and pressure.

Can you close a needle valve?

Since flow rates are low and many turns of the valve stem are required to completely open or close, needle valves are not used for simple shutoff applications.

What is the difference between a flow control and a needle valve?

While the basic function of both the fittings is flow restriction, the main difference is that the needle valve controls the flow of liquid or gas in both directions, while the flow control valve only ensures control in one direction only.

Can a ball valve be used for flow control?

Simply put, a ball valve is an on-off valve. It can be used to control flow by its main characteristic, the ball, being open or closed. Ordinarily, this only requires a quarter-turn of the ball valve handle.

Which is better ball valve or needle valve?

A needle valve is used for smaller flow rates that must be precisely controlled. A ball valve is a general purpose valve. It is usually a bit more expensive than a gate valve or a globe valve but performs better and lasts a bit longer.