Regulating Valves
These valves are special devices designed for regulating Pressure and Flow Rate of water. The valves used for this purpose are commonly known as ‘PRV’.
What is a PRV?
PRV is a control valve, where ‘R’ stands for Reducing/Regulating/Relief, simultaneously performing these functions based upon application.
- Pressure Reducing Valve – for energy dissipation at the outlet.
- Pressure Regulating Valve – for flow regulation based upon requirement.
- Pressure Relief Valve – for safety relief by limiting Pressure rise in the system.
Design Criteria
When a PRV is needed, its design must fulfill the following criteria:
- Noise level must not be hazardous for the people working in the power station.
- Valve must dissipate a large amount of energy in the water, not to cause problem at downstream.
- When the valve opens water flow must not be dangerous for both personal and structures.
Applications
- In bypass PRV is used in end of line solution for energy dissipation and flow regulation.
- In turbine transient regulation PRV is used as a safety device with simultaneous functioning of flow regulation and energy dissipation.
Types of Valves used as PRV
- Conical Jet Valve (CJV)
- Plunger Valve (PLV)
- Slide Valve (SLV)
- Needle type Valve
Conical Jet Valve
CJV are used as free discharge devices in pressure piping systems.
Fixed Cone Valve – Controls and dissipates enormous amount of energy by breaking up the discharge water into a large hollow expending jet. Suitable for submerged application.
Ring Jet Valve – similar to fixed cone type it has an internal hood that concentrates the discharge spray into a jet. Not suitable for high heads and submerged applications.
Advantages on Conical Jet valve:
- More cost effective
- Lower maintenance
- Adaptable to manual, hydraulic and electric actuators.
- Dissipates enormous energy by breaking up discharge water into large hollow jet.
Plunger Valve
Plunger Valve is a type of control valve with annular flow cross-section for continuous regulations at high pressure differences and flow rates.
PLV plunger valves are used as shut-off and regulating devices in pressure pipe systems.
Types of Plunger Valve
- Cut-off edge: It has a sudden enlargement of cross-section area at the seat and is suitable for regulating flow where enough back pressure is present.
- Slotted cylinder: Suitable to regulate/control water with suspended solid particles and prevention of cavitation in case of high-pressure difference.
- Perforated cylinder: Suitable to regulate/control flow and prevention of cavitation in case of high-pressure difference.
Advantages on Plunger Valve
- Suitable for high pressures.
- Adaptable to manual, hydraulic and electric actuators.
- Valve with counterweight acts as a safety device and ensures fail safe opening.
- Longer service life as bearings are not in contact with medium.
- One-piece compact body design.
Slide/Sleeve Valve
Slide Valves are designed with a self-closing tendency. The opening is controlled hydraulically or by suitably designing it for its own medium.
SLV slide valves are used as shut-off devices in pressurized piping system.
Advantages on Slide Valve
- Suitable for high pressures.
- Compact design.
- Low head loss.
- Lower maintenance and very long service life.
- Low vibrations and sound levels.
- Higher wear and corrosion resistance as complete valve is made of stainless steel.
Needle type Valve – synchronized application with turbine
It is a safety cum regulating device suitable for projects having Francis & Kaplan units in order to limit pressure rise and speed rise in permissible range.
Advantages on Needle type Valve
- Fail safe safety device, as mechanical / hydraulic linkages are used for synchronous operation with turbine.
- Lesser noise and vibrations as water is discharged through large orifice cylinder.
- Highly effective in energy dissipation/pressure reduction.
- Highly effective in flow regulation as per the control requirement of turbine transient.
Selection Criteria
| Valve Type | Size (DN) in mm | Pr. Rating / Class | Application |
| CJV | 500 – 2,000 | PN 6 – 50 (40*) | Bypass |
| PLV | 300 – 1,400 | PN 6 – 25 (40*) | Turbine transient regulation |
| SLV | 50 – 300 | PN 16 – 150 | Bypass |
| Needle | 200 – 1,000 | Pn 6 – 40 | Turbine transient regulation |
About FLOVEL:
FLOVEL name has been synonymous with the hydro power sector for over four decades. FLOVEL is a full-line supplier of electromechanical equipment and services for small and medium size hydro power plants manufacturer of hydraulic turbines, valves and turnkey supplier of electro mechanical packages for hydro power projects and ranks amongst the leading players globally. FLOVEL manufacturers complete range of Pelton, Francis, Kaplan, Axial Flow turbines and Valves for hydropower projects. The strength of FLOVEL is in its ability to offer all-inclusive solutions (Electro Mechanical-Turnkey Packages).
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