Check valve types pdf

Low Prices - Huge PVC Warehouse. Valve Types and Features. The three basic functions of valves are: 1. To select the correct valve to fulfill these functions properly, an outline of the different types of valves and their features is given below.

Basic Types by function.

Check valve or non-return valve , allows the fluid to pass in one direction only. Flow control valve to maintain and control a variable flow rate through the valve. Poppet valve commonly used in piston engines to regulate the fuel mixture intake and exhaust.

A common type of check valve found in plumbing in general practice and fluid systems in plants is the flap type. This can be seen generally in pump sets used in buildings or in agricultural forms. As foot valves the plunger type check valve is also very common at suction of water pumps in buildings. It is also common in construction and sewage.

The principle is simply a knife or gate which is dropped in front of the flow.

Knifegate valves should never be used in a restrictive role (ie half open) as the base of the knifegate will wear rapidly and not seal properly when closed. Most commonly used are plate valves , ring type valves and poppet valves. Depending on the application different types could be used for a recip compressor. Swing check valves are armatures (valves) for return fl ow prevention in piping systems.

Easy structures and short dimensions are the remarkable features of ZRK-ZRKF-swing check valves. They are constructed to be mounted directly bet-ween fl anges acc. In piping following types of valves are used depending on the requirements. And the cost of a given type and size of the valve can vary 1. It means that if you choose ball valve over butterfly valve for the same function. The Disc check valves are opened by the pressure of fluid and closed through compression spring as soon as flow stops thus preventing reverse flow.

A basic check valve consists of a valve body, bonnet or cover, and a disc which is attached to a hinge and swings away from the valve seat to allow fluid to flow in the forward direction, as in a swing- or tilting-disc check valve , and returns to valve seat when upstream flow is stopped. Thus, reverse flow is prevented. Many series are available to provide check valves for practically every service application.

In a flap type check valve , the disc swings on a hinge along its top. In a butterfly type check valve , the disc swings on a lateral trunnion closer to its center, but still slightly above center. Often applied on the discharge side of pumps, check valves prevent the system from draining if.

Sealing is by differential pressure.

The gate design is always of the through conduit type incorporating an aperture the same diameter as the valve bore. When the gate is in the fully open position it allows free and uninterrupted flow. Class 1gate valves consist of a square joint in 2” and an oval one for all other sizes.

Class 3and 6valves consist of a circular spiral wound gasket. Class 9and above gate valves consist of a ring type joint. The ratio (FL) of the valve flow coefficient (Cv) based on the pressure drop at the vena contracta, to the usual valve flow coefficient (Cv) which is based on the overall pressure drop across the valve in non-vaporizing liquid service.

SECTION INDEX OF GATE VALVES Low operation torque design. PID SYMBOL Outside Screw and Yoke (OSY). Standard construction of body-bonnet connections are bolted bonnet or welded bonnet type. They are designed such that if the air supply fails, the control valve will be either fully open, or fully close depending upon the safety requirement of the process.

This operation is slow, but it gives accuracy and stability to position the closure member, which is necessary in some control valves. Types of valves: Gate valve , Globe valve , Fixed cone valve , Needle valve and Pinch valve.