Check Valves BS 1868 ASME B 16.34

Flowtorq Engineering is best manufacturer of check valves often known as non return valves. A check valve is having totally different function in comparision with other valves. Also known as non-return valve or reflux valve is a valve that normally allows fluid (liquid or gas) to flow through it in only one direction. And opposes the flow in any one specified direction. It is designed as per BS 1868, API 6D, API 594, BS 5352, ASME B 16.34, etc. standards. It consists of a swing type disc element or a lift type plug, disc or a ball as a closure member assembled inside of body, resting on the seat surface. These valves are named for their back flow prevention function. These are self operated valves, normally are actuated by reverse fluid flow either by gravity or by back pressure. Arrows are marked on valve body to indicate permissible flow direction. When the flow is towards the permitted direction, the disc or plug is raised from seating and the opening allows flow passage. When the flow is reveresed, the back flow causes the disc or plug to move to its original position and rests on the seat surface thereby preventing flow, e.i. closure of valve.

Function

These are widely used for back flow prevention. Usually, after the discharge line of pumps or equipment, non return valves are installed to prevent back flow. Reactors, Reaction vessels and compressor discharge line often has a non return valve installed to prevent back flow and cause disruption in flow or process. Pumps which needs priming are having chekc valves installed in suction lines to keep the downstream volume and little upstream volume of liquid to preven long dry run and equipment damage. Apart from indsutrial applications, there are ample of domestic and sanitary use of these valves.

Operation

Commonly, swing check valves ( BS 1868, ASME B16.34 ) are having a tilting disc fixed to a hinge inside valve body. This disc is often called as swing disc or tilting disc. When there's no flow, the disc rests itself on the body seat and the valve is closed. When the flow is towards the permissible direction, the flow volume and pressure causes the disc to move upwards and thus the flow passage is open. When there's a back flow condition ( when the flow becomes reverse in the non permissible direction of valve), the flow volume and pressure causes the disc to fall and close the flow passage thereby stopping the reverse flow from the valve to the equipment. Similarly lift type valves ( BS 5352 ) are built with plug disc or ball inside its body and a spring (with pre calculated tension as per flow requirement, cracking pressure and plug / ball weight). The pressure exerted by the flow causes the plug disc or ball to rise from it's seat and open the flow passage, while during the back flow, the ball or plug disc gets seated into it's original position due to back flow pressure and force exerted by spring. Other Valves include Dual Plate type valves ( API 594 ) which are having a split disc connected to a stem or pin. A spring is fixed on to stem and it exerts continuos pressure on discs to keep the valve in close position. During the flow, the pressure exerted by the flow causes the disc to open and during back flow, the spring force, in addition to flow pressure causes the disc to close the flow passage.

API 594 dual plate check valves

Construction as per BS 1868 ASME B 16.34 API 594

Swing Check Valve

A swing check valve (or tilting disc check valve as per BS 1868) is a valve in which the disc, the movable part to block the flow, swings on a hinge or trunnion, either onto the seat to block reverse flow or off the seat to allow forward flow. The seat opening cross-section may be perpendicular to the centerline between the two ports or at an angle. Although swing type can come in various sizes, large types are often swing type. A common issue caused by swing type valves is known as water hammer. This can occur when the swing disc closes and the flow abruptly stops, causing a surge of pressure resulting in high velocity shock waves that act against the piping and valves, placing large stress on the metals and vibrations in the system. Undetected, water hammer can rupture pumps, valves, and pipes within the system. These are strictly in compliance with BS 1868.

Dual Plate Check Valve

Dual Plate Check Valves ( as per API 594) are automatic self operated valves, which open with a forward flow and shut a reverse inflow. The key feature of the check valve is to secure the mechanical equipment in the piping system by avoiding the reverse flow. The swing type valve is an economic kind of non return valve, but has a higher slamming effect. Dual plate type valves are more common than swing type in various industries as they have a low slamming effect. In addition, the cost of the dual-plate type valves is well below the swing type.

Lift Check Valve

Lift check valve ( as per Bs 5352) is also a type of valve used to prevents backward flow. Lift type valves allow fluid to flow in one direction only. Lift type check valve is applicable and suitable for use in high-pressure service applications where the flow velocity is high. Lift type valve designs are typically type of valve to have the disc or ball guided accurately with contact slide and with a centered dashpot seat. Lift type non return valves can be installed in vertical or horizontal orientation.

Wafer Check Valve

A wafer check valve ( as per ASME B 16.34 ) looks like butterfly or wafer-type disk used to open and close fluid flow. A wafer valve has two ports that is the inlet and outlet port. The disc moves like swing and valve opens when the inlet side pressure becomes more than the cracking pressure. When the inlet side pressure becomes less, the disk is forced to shut the wafer valve. Wafer valve are compact and with slim bodies. Despite the body being slim, the valve body is very strong enough to sustain high pressure and high temperature. Wafer type valves are lightweight and compact are used in different industrial applications. These valves are economical and they are available in different sizes, different flow rates, and different materials to best suit different applications.

Non Slam Check Valve

The non slam check valve refers to NON SLAM type operation. The disc does moves to open and close the flow passage but the slamming effect like in swing type are eliminated. Due to no noise and vibration in this valve, it is also known as nozzle type valve. The non slam non return valve belongs to an automatic self operated valve type. Similar to its counterparts, its main functions are to prevent back flow of the medium, prevent the pump and drive motor from reversing, etc. BS 1868, API 6D, API 594, BS 5352, ASME B 16.34.

Applications

Industrial applications such as oil and gas, petrochemicals, chemical, power generation, mining and industries use this valves. Check valves are widely used for back flow prevention. Usually, after the discharge line of pumps or equipment, non return valves are installed to prevent back flow. Reactors, Reaction vessels and compressor discharge line often has a non return valve or a check valve installed to prevent back flow and cause disruption in flow or process. Pumps which needs priming are having chekc valves installed in suction lines to keep the downstream volume and little upstream volume of liquid to preven long dry run and equipment damage. Apart from indsutrial applications, there are ample of domestic and sanitary use of these valves.

Why Select and Use Flowtorq Check Valves ?

Easy Availibility
Wide range of types
Good for handling critical processes
Economic Cost
Wide Range of Size from 1/2" (half inch) to 30" (inches) and large sizes
Wide Range of pressure rating capacity from 150# low pressure to 2500# high pressure and above
Easy Maintenance and handling
Rigid and Robust Construction
Wide Variety of internal trim parts variants
Long Service Life

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asme b 16.34 wafer type non return valve

General Specifications of check valves

Size Range – 1/2″ to 30″ and above
Types - Swing type Valve, Lift type Valve, Dual Plate type Valve, Wafer type Valve, Non Slam Disc type Valve (spring loaded), etc.
Pressure Rating – 150#, 300#, 600#, 800#, 900#, 1500#, 2500#
Certifications – IBR, CE, etc.
Inspected & Witnessed By third party agencies
API Valves, ATex Valves, CE Valves, Process Valves, Gas Valves, Water Valves, Cryogenic Service, Fire Safe