Check Valve

A check valve is a mechanical device that allows the flow of fluid in one direction while preventing its backflow in the opposite direction.

Check valves are generally installed in pipelines to prevent backflow. A check valve is basically a one-way valve, in which the flow can run freely one way, but if the flow turns, the valve will close to protect the piping, other valves, pumps etc.

What is a check valve used for?

Check valves are generally installed in pipelines to prevent backflow. A check valve is basically a one-way valve, in which the flow can run freely one way, but if the flow turns, the valve will close to protect the piping, other valves, pumps etc.

What is the difference between a backflow and a check valve?

Check valves use a hinged plug that allows water to pass through the pipeline but blocks it from coming back. Backflow preventers, on the other hand, apply an increased amount of pressure on a pipe to ensure the water can only flow one way.

Most common types of Check valves are swing, lift (piston and ball), butterfly, stop and tilting-disk.

Swing Check valve

A basic swing Check valve consists of a valve body, a bonnet, and a disk that is connected to a hinge. The disk swings away from the valve-seat to allow flow in the forward direction, and returns to valve-seat when upstream flow is stopped, to prevent backflow.

The disc in a swing type Check valve is unguided as it fully opens or closes. There are many disk and seat designs available, in order to meet the requirements of different applications. The valve allows full, unobstructed flow and automatically closes as pressure decreases. These valves are fully closed when flow reaches zero, in order to prevent backflow. Turbulence and pressure drop in the valve are very low.

Lift Check valve

The seat design of a lift-Check valve is similar to a Globe valve. The disc is usually in the form of a piston or a ball.

Lift Check valves are particularly suitable for high-pressure service where velocity of flow is high. In lift Check valves, the disc is precisely guided and fits perfectly into the dashpot. Lift Check valves are suitable for installation in horizontal or vertical pipe-lines with upward flow.

Flow to lift Check valves must always enter below the seat. As the flow enters, the piston or ball is raised within guides from the seat by the pressure of the upward flow. When the flow stops or reverses, the piston or ball is forced onto the seat of the valve by both the backflow and gravity.

Key features of a check valve include:

Flow Direction Control: Check valves permit fluid flow in one direction and automatically close to prevent backflow in the opposite direction.

Mechanical Design: Typically, check valves consist of a hinged or spring-loaded flap, disc, or piston that opens with forward flow and closes with backflow, creating a unidirectional flow path.

Various Types: Check valves come in different designs, including swing check valves, lift check valves, ball check valves, and diaphragm check valves, each suited for specific applications and conditions.

Versatility: Check valves find applications in various industries, such as water and wastewater systems, oil and gas pipelines, HVAC systems, and more.

Preventing Water Hammer: Check valves help prevent water hammer, a sudden pressure surge that can occur when fluid flow is suddenly halted.

Low Maintenance: Due to their simple design, check valves are generally low maintenance, providing reliable and efficient operation over extended periods.

Sizes and Materials: Available in a range of sizes and materials, check valves can be customized to suit specific system requirements, including different pressures and temperatures.

The Difference Between Backflow Preventers and Check Valves

It’s no secret that backflow is one of the most prevalent threats to the purity of our local water supply. Not only can contamination happen everywhere, but it can happen at any time if your plumbing system isn’t set up to prevent it. As such, business professionals, school administrators, and homeowners are all setting out to stop this occurrence and protect the quality of their drinking water. However, this process often comes with confusion regarding what equipment they should use for the job. This article covers the difference between backflow preventers and check valves.

Construction

Though backflow preventers and check valves have the same overall function, they both work slightly differently. Check valves use a hinged plug that allows water to pass through the pipeline but blocks it from coming back. Backflow preventers, on the other hand, apply an increased amount of pressure on a pipe to ensure the water can only flow one way.

Reliability

Backflow systems are generally more effective at keeping wastewater flowing in the correct manner because they’re highly pressurized. They also have several additional fail-safes that further protect our more sensitive drinking water sources. Check valves have a decent amount of reliability. However, they can fail under the right conditions and contaminate certain supplies with sewer water.

H71 pinch check valve with precision cast valve body.

What are valve standards?

Many kinds of valves are used in the industrial process, and to ensure proper functionality, compatibility, and safety for end-users, EPC, or engineering, every country has particular organizations to make standards.

The major standard organizations include the American National Standards Institute(ANSI), American Petroleum Institute(API), The American Society of Mechanical Engineers(ASME), British(BS), China valve standards(GB, JB, HG), and so on. THINKTANK provides standard resources for all interesting valves friends study.

ANSI Valve Standards

American National Standards Institute

API Valve Standards

The American Petroleum Institute

ASME Valve Standards

The American Society of Mechanical Engineers

BS – British Standard Valves

British – BS – valve standards

China and International Valve Standards

Fluid Control Institute (FCI)

The Fluid Control Institute (FCI) provides standards and other materials to assist purchasers and users in understanding and using fluid control and conditioning equipment such as control valves, solenoid valves, and regulators.

Quality Control

A valve can be described as a mechanism that controls the passage of liquids through a pipe. Research states that valves being manufactured in China are amongst the top valve competitors in the valve industry.

Nondestructive Test

Radiography Inspection guarantees no failures inside of the castings or forgings. Ultrasonic inspection acts an alternative of inspection. Dye penetrant testing and magnetic particle testing can examine surface failures on castings and forgings.

Cryogenic Treatment

-196 ℃ Cryogenic Treatment System is a basic treatment for LNG usage valves or similiar applications.

Leakage Test

Leak testing is a procedure that inspectors use to determine whether an object or system is functioning within a specific leak limit.

Chemical Analysis

All our materials are strictly made under supervision of ladle analysis instrument in the foundries and inspected by high precision spectroanalysis instrument when they arrive in our plant.

Mechanical Properties Test

All mechanical properties test will act before we use the materials to secure the performance and safety.

Heat Treatment

Up to 1200 ℃ electric furnance provide an availability of various heat treatment cycles.