Double Check Valves

How Does Double-Check Valve Work

A check valve must have an upstream threshold pressure (the difference in pressure between the inlet and exit) to open and allow media through. The check valve's "cracking pressure" is the lowest upstream where the valve opens. It is important to ensure that the system's pressure can produce the breaking pressure of the selected check valve because the particular cracking pressure varies depending on the valve's design and size. In systems like fire sprinklers and grass irrigation, reverse pressure and back siphonage are avoided using a dual valve backflow preventer.

A single check valve is frequently employed for hydraulic category two protection when there may be variations in the fluid's temperatures, flavor, or odor. For fluid category three safety, which covers compounds with low hazardous levels, a double-check valve is frequently utilized (like common disinfectants).

Closing

The check valve will close if the upstream pressure drops underneath the breaking pressure or if there is backward flow. The gate on a check valve typically closes the valve by pressing against a seal. The process of shutting might be aided by gravity or a spring. The valve is closed by gravity, a spring, or by utilizing backpressure as soon as the inflow pressure drops just below splitting pressure or backpressure.

Orientation for installation

Given that one-way valves only permit flow in one direction, understanding the right installation orientation is crucial. Usually, a flow direction indicator is an arrowhead on the valve casing. If there isn't an arrow, it is important to ensure the valve is installed in the proper flow direction by looking at it. Media won't be able to flow through the system if the valve is fitted backward, and the consequent pressure buildup may result in damage.

Check valve materials

Brass check valve

For applications involving liquids like water, oil, and fuel, brass check valves are fantastic. They are not, however, resistant to chlorinated, filtered, or seawater. They are primarily utilized for low-pressure applications and are less heat and corrosion-resistant than stainless steel.

Stainless Steel Check valve

Check valves of stainless steel have outstanding mechanical qualities and exceptional resistance to rust, heat, and low temperatures. Relative to brass check valves, stainless steel is often not a cost-effective alternative for applications that do not require significant durability or resistance. High-quality check valves of stainless steel wafers are frequently used in elevated and high-pressure applications.

Cast Iron Check Valves

High-temperature check valves are often made of cast iron. Cast iron has high strength and vibration resistance. In addition, the material is extremely temperature- and wear-tolerant and has exceptional wear resistance. Cast iron, however, is not naturally ductile. Therefore, any bending could result in the cast iron substance cracking and losing its usefulness. Cast iron can withstand higher temperatures than PVC but erodes with time. These valves are used in the sugar and paper industries and oil lubrication systems.

PVC (polyvinyl chloride) Check valve

Systems for water and irrigation management often include plastic check valves made of PVC or CPVC. Most corrosive media, including saltwater chloride solutions, and organic solvents, do not affect their corrosion resistance. However, they are not resistant to chlorinated or aromatic hydrocarbons, and their normal maximum temperature resistance is only about 60 °C.

Selection Standards

When choosing a check valve for an application, several factors must be considered. Some of them include the following:

• The material's suitability for the medium
• Connection point size for lines
• The maximum pressure and required cracking pressure
• Horizontal or vertical for installation
• Envelope measurements
• Accessibility requirements for evaluations and maintenance
• Temperatures

Applications

Check valves are frequently employed in several applications for one of many reasons because of the way they work:

• To prevent downstream equipment from being damaged by backflow
• Avoiding pollution brought on by the reverse flow
• To stop siphoning
• Maintain a vacuum seal

The valves are used in practically every industry due to their primary function. They are applied to typical home appliances and Industries.

Choosing the Right Double Check Valve Supplier

To ensure the most beneficial outcome when purchasing double check valves from a double check valve company, it is crucial to compare several manufacturers using our directory of double check valve suppliers. Each double check valve company has a profile page highlighting their areas of experience and capabilities, along with a contact form to directly communicate with that manufacturer for more information or to request a quote. Review each double check valve business’s website using our patented website previewer to get an understanding of what each company specializes in, and then use our simple RFQ form to contact multiple companies with the same form.