6. Flow control FCV, non-return valves

Flow control FCV, non- return valves {Hydraulics} Making India Employable

Flow Control Valve? • The valves which are mainly used to regulate the flow of fluid in hydraulic circuits are known as “flow control valves”. The flow control valves are widely available in many different types according to their use. • In hydraulics, flow control valves are used to control the amount of oil supplied to various parts within a hydraulic system. In this way, the momentum of a cylinder or the rotational speed of a hydraulic motor can be controlled. • However, a basic flow control valve has an opening that can be changed to increase or decrease the flow rate. The many benefits of using flow control valves include the variety of materials from which they can be made (such as brass, carbon steel, stainless steel, and zinc). • Flow control valves can provide many choices for simple and complex systems that adjust for pressure, temperature, and other flow variables. For internal Training purposes only

Parts of Flow Control Valve Following are the parts of the flow control valve: 1. Body 2. Bonnet 3. Trim 4. Disk and seat 5. Stem 6. Actuator 7. Handwheel 8. Valve packing For internal Training purposes only

#1 Body It is the main part of the flow control valve, in which all other parts are kept together by a structure called the body. The piping in the valve body is achieved with the help of bolts and welded joints. It is usually made of cast iron and is also called a valve shell. #2 Bonnet The bonnet is a cover that is used for the opening in the body and is divided into two parts which are fastened together. Some valve bonnets are used only as covers while some of them are used for valve interior accessories. #3 Trim The trim is usually presented on the inside of the valve and consists of the stem, sleeve, seat, and disc. Valve performance can be detected by the seat and disc interface. For internal Training purposes only

#4 Disk and Seat A disc is an essential part of the flow control valve that allows and restricts fluid flow. If the disc is in the closed state then the total system pressure is applied to the disc and the pressure is exerted towards the outlet. #5 Stem These are liable for the connection of the actuator and the disc, which holds the disc in position. The connection is done by the threads and welded joints. Generally, two types of the stem are used which are non-rising stem and rising stem. #6 Actuator This is the main part of the flow control valve, which is driven by the stem and disc assembly. Control valve actuators may be operated manually or by an electric motor. For internal Training purposes only

#7 Handwheel It is a common type of valve actuator. A valve handwheel is used to manually control the opening and closing of the valve. #8 Valve Packing It is a sealing system, that has a deformable material in the solid form or split rings held in a packing box. These are used for packing in valves which consequently prevents leakage between stem and bonnet. For internal Training purposes only

Working of Flow Control Valve The flow of the fluid can be controlled by changing the place through which it is passing. In this, a pressure drop occurs and this must be considered when choosing a flow control valve. In a hydraulic circuit, the pressure fluctuates across the load, sometimes more or less. Although the inlet pressure is constant, the pump is delivering fluid at constant pressure but the outlet pressure can vary. To avoid this fluctuation in load we can easily install a pressure compensated flow control valve. By using this flow control valve, the flow rate can be kept constant even under variable loads. These valves have a spool and by changing the position of the spool, the field direction of the passage can be adjusted. Therefore, the required flow can be maintained during the flow of the fluid through the control valve. For internal Training purposes only

Types of Flow Control Valves Following are the types of flow control valves: • Gate valve • Plug valve • Needle valve • Non-return valve • Butterfly valve • Pressure compensated flow control valves • Pinch valve • Globe valve • Diagram valve • Ball valve For internal Training purposes only

#1 Gate Valve #2 Plug Valve • The valve controls the flow of the oil in a • As the name suggests, this valve is having a pipe by moving a flat plate called a gate or plug. This plug can be turned to move its disc valve. Gate is built perpendicular to ports to control the flow of oil and it the length of the pipe with the help of a features to reduce the friction between the handwheel. plug face and the body seat when the turning of the plug. • This mechanism is achieved by connecting the gate with the handwheel through a • The valve consists of a tapered wedge threaded spindle that rotates in the valve mechanically seated in the body. The body. The advantage of a gate valve is that tapered edge has a rectangular window. it offers little or no resistance to flow when When the valve is fully open rectangular it is fully open. It is usually made up of window aligns itself with the holes running gunmetal. through the valve body.

#3 Needle Valve #4 Non-return Valve • It is a kind of screw-down stop valve. Its • The non-return valve permits flow in one use is restricted to small sizes which have direction and stops the flow completely in the body ends in line or right angles with one direction and stops the flow each other or maybe oblique type. completely in one direction. It consists of a valve body, a poppet, a spring, and a seat. • Here disc is in the form of needlepoint. By rotating the handwheel, the tapered • When the force of fluid is available at the needle advances, and the area of the valve inlet port exceeds the strength of the seat decreases. Hence the oil flow is spring and the backpressure of oil the gradually reduced. These valves are used in poppet is pushed up and the valve opens to hydraulic systems in lines of delicate permit the flow through it. When the oil is pressure gauges. flow is reversed, the valve piston is pushed back to its seat, completely blocking the flow.

#5 Butterfly Valve #6 Pressure Compensated Flow Valve • The butterfly valve has a circular disc that • The pressure compensation flow valve can be rotated through one complete provides a uniform volume flow rate revolution. The circular disc has a diameter independent of the pressure drop across equal to that of a pipe. the valve. On the other hand, the non- pressure-compensated valves have a • The valve is connected across both faces by variable flow rate that changes as the two pipes with flanges. A circular disc is pressure in the valve fluctuates. made to rotate around an axis passing through the vertical diameter of the disc. This type of flow control valve is used for controlling moderate flow.

#7 Pinch Valve #8 Globe Valve • These are types of flow control valves, • These are considered valuable for starting, which are inexpensive and are used in stopping, and regulating the flow in a linear motion. almost all industries. It consists of flexible Globe valves are used for throttling applications elements such as rubber tubes for sealing because the disc of the valve can be completely purposes. They are designed to give a tight removed from the flowline and are also capable of seal around trapped solids with their closing the flowline completely. flexibility, these rubber tubes are the • Unlike the other types that are straight-through moistened part in a pinch valve. valves, these valves produce slightly high-pressure • Pinch valves are perfect for liquids that drops. The closure in a globe valve is opened by contain large amounts of suspended solids. means of a plug that covers a flat bottom and is The valve body acts as a built-in actuator, then lowered onto a horizontal seat in the center of reducing the need for expensive operators this valve. The plug in the globe valve lifts when the such as pneumatic, hydraulic, or electric user opens it, and this allows the fluid to flow. operators.

#9 Diaphragm Valve #10 Ball Valve • These valves are built to handle conditions • Ball valves are commonly used in a variety that require erosive, corrosive, and dirty of industries because of their low cost, services. It consists of a flexible disc that durability, and excellent closing capability. reaches the top of the valve body along These are similar to a butterfly valve, they with the seat to form a seal. These are used are not suitable for flow control to control the opening or closing of the applications as they require high accuracy valve. and control. • These valves work by an elastomeric • This is because a high level of torque is diaphragm in the valve body, rather than required to open and close a ball valve an elastomeric liner, which is attached to a which prevents an operator from making compressor to isolate the closure element fine adjustments. The ball valve is used for from the fluid flow. This gives the filling a tank with reasonable accuracy. A advantage that they feature a leak-proof trunnion or V-port ball valve design is seal and are easy to maintain. usually the best type.

NRV (Non-Return Valve) NRVs (or non-return valves) are installed within hydraulic systems in order to prevent hydraulic fluid flowing in the opposite direction to which it is intended. A non-return valve allows a medium to flow in only one direction and is fitted to ensure that the medium flows through a pipe in the right direction, where pressure conditions may otherwise cause reversed flow. The flow through the non-return valve causes a relatively large pressure drop, which has to be taken into account when designing the system. There are different types of non-return valves, such as spring- loaded, swing type, and clapper type valves. Non-return valves are for example used with mixing loops in heating and cooling systems to ensure proper operation, and with domestic water systems to prevent backflow. For internal Training purposes only

How Does A Non-return Valve Work? A non-return valve, also known as a check valve, clack valve, one-way valve or retention valve, is designed to allow fluid to flow in one direction only, therefore preventing the liquid or gas from flowing back upstream of the valve. A non-return valve usually only has two openings in the body, with a closing member situated between them. Whenthe fluid enters the valve its pressure holds the closing mechanism open. If the fluid attempts to flow back through the valve in the wrong direction, the closing member is forced back over the entrance of the valve preventing any flow. Non-return valves work automatically, which means that most are not controlled by a person or an external control but by the media flow itself. Depending on exactly What a non-return valve is used for, where it is used, the media flow and the budget available, there are a variety of different types of design to select from according to the specific application. Types of non-return valve include those designed using a diaphragm, a swing or tilting disc, a stop, a lift, or a ball non-return valve. For internal Training purposes only

Which Applications Is A Non-return Valve Used For? • Pumps: Many pump applications include non-return valves to prevent backflow on the pump head on both the inlet and outlet lines. For example, the feed pumps for steam boilers would usually have a check valve fitted, as well as metering pumps, used to maintain a flow rate at a specific outlet pressure. They are also found in chromatography, which is a laboratory purification method for separating out components of a mixture. • Industrial processes: Fluid and processing systems, such as those found in power plants and pharmaceuticals, as well as fuel systems on transportation, commonly use non return valves within their pipeline systems. An example of what a non-return valve is used for in the nuclear industry could include within the dump lines, in the nitrogen feed system and in areas where water control systems are used. Non-return valves are used in fuel injection systems; the injectors are simply check valves which are designed to work with a high opening pressure and would be found in aircraft fuel systems as well as on spacecraft where the launch vehicle would use include them in the propulsion propellant control. • Domestic uses: Home heating systems, sprinkler systems and inflatable mattresses all use non-return valves. In some cases, the non-return valve can be a critical safety feature, for example to prevent contaminated, used water from re-entering a domestic water supply. For internal Training purposes only

For internal Training purposes only

https://www.youtube.com/watch?v=jbOdnEwUYOw Flow Control Valves in Hydraulics

https://www.youtube.com/watch?v=9cosVSstZ88 Hydraulic || Flow Control Valves || FCV

https://www.youtube.com/watch?v=-sso1yk4Oo0 Non return valve. How does a check valve work?

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