Non-return valves are threaded
All three versions have a threaded connection and tightness class "A". They differ in design, materials, permissible temperature and list of working media. Current diameters and prices can be viewed in the product cards.
How a threaded check valve works
The valve allows flow in only one direction and automatically closes when the medium stops flowing or reverse flow occurs. Inlet pressure moves the ball, disc, or spool away from the seat and opens the passage. When the pressure is released, the shut-off element returns to the seat under the action of its own weight, flow, or spring, depending on the design.
This principle helps to maintain the filling of the pipeline, prevent the pump from rotating backwards and separate sections of the system. The valve does not create pressure and does not replace the safety valve. For stable operation, it is necessary to observe the installation direction indicated by the arrow on the body.
Types of threaded check valves
In the C302 ball model, the flow lifts the ball and when stopped, it returns to the seat. This design is suitable for the following environments:
- water;
- air;
- waste and sewage water;
- petroleum products within the product parameters.
The NBR coating ensures contact with the seat and affects the tightness.
The rotary C321 has a disc mounted on a stem. When the medium moves, the disc deflects, and when the direction changes, it closes the passage. The C322 also uses a stainless disc, but the exact mechanism diagram and the presence of a spring should be checked in the technical passport. The spring valve is less dependent on the spatial position, but creates additional resistance to opening.
How to choose a valve by diameter and working pressure
First, determine the pipeline diameter and thread parameters. DN25–DN80 is available for C302, while stainless steel C321 and C322 are available in the range of DN15–DN100. All models in the category are marked PN16, but when choosing, you need to take into account the actual operating pressure, temperature and possible water hammer.
The minimum opening drop, pressure loss and flow rate are important. A valve that is too large may operate unstable, and a valve that is too small may create excessive resistance. If the product is installed after the pump, the selection is made according to its flow, pressure and start-up mode. For heating systems, the temperature of the coolant is additionally checked.
Housing and locking mechanism materials
The valves are available in cast iron and stainless steel, so they are selected taking into account the environment, temperature and corrosion resistance requirements. The C302 body is made of high-strength cast iron EN-GJS500-7, and the ball is made of EN 1.0619 steel with NBR. The model is designed for temperatures up to +80 °C. This design is suitable, in particular, for water and wastewater, if their composition is compatible with the elastomer.
The C321 body and disc are made of stainless steel EN 1.4301, and the stem is made of EN 1.4401. The C322 body is made of EN 1.4308, the disc is made of EN 1.4301. Both stainless steel models are rated for temperatures up to +180 °C, but the permissible temperature depends on the medium. Brass and bronze are common in small diameter couplings, but this page presents cast iron and stainless steel versions.
Where to buy a threaded check valve
You can buy a threaded check valve from UKSPAR with a selection for a specific system. For calculation, please inform the working medium, diameter and type of thread, maximum pressure and temperature, required installation position and pump characteristics.
Before installation, clean the pipeline, check the flow arrow, and use a compatible thread sealing material. UKSPAR specialists will help you compare ball, swivel, and disc options, check availability, and arrange delivery across Ukraine.