Check Valves

Introduction
Check valve, also known as non return valve, reflux valve, one way valve or counterbalance valve, belongs to automatic valve, which is installed on one-way flow pipelines. It is mainly made up of valve body, disc, bonnet and gasket. It is used to prevent reverse flow and leakage of medium, such as fluid, gas, etc. This type of pipe valve is also applied to stop reversal of pump and driving motor. Check valve can be widely applied in tap water, sewage, construction, petroleum, chemical, food, medicine, textile, electric power, shipbuilding, metallurgy, and other pipeline systems.

Advantages
1. Small friction between sealing surfaces ensures low wear rate of check valve (non return valve, reflux valve or one way valve).
2. Two times shot blasting of valve surface make the valve look fine and smooth.
3. CNC processing technology is adopted to produce disc.
4. Disc is with high strength and stiffness.
5. Disc restrainer is designed to prevent that the open position of disc is too high to be shut down.
6. Check valve features small closing torsion and excellent sealing performance.
7. High intensity and flexibility of rocker are beneficial to close disc.
8. The disc sealing surface can be customized. Customer can choose sealing material according to media in order to increase sealing property and wear resistance.
9. Our pipe valves have passed API6D, DIN and CE certification.

Classification
1. According to structure, check valves can be classified into lift type (including vertical type and horizontal type), swing type (with single plate, dual plates and multiple plates) and butterfly type (straight through).
2. According to connection type, the above valves can be divided into threaded connection, flanged connection, welded connection and wafer connection.

Working Principle
Check valve (non return valve, reflux valve or one way valve) opens and closes automatically depending on force from media flowing. It allows medium to flow through it in only one direction, and prevents reverse direction flow. Disc will open under the pressure of forward flow fluid. When fluid flows in reverse direction, the disc will be closed by fluid pressure and dead weight so as to cut off the flow.

Malfunction, Reason and Solution

Attentions
1. Before installing check valve (non return valve, reflux valve or one way valve), please make sure
1) The valve conforms to operating requirement.
2) No dirt is attached to valve cavity.
3) Screw bolt is evenly screwed down.
4) The opening and restoration performance is flexible (by pushing the disc from entrance).
2. When installing the valve, please ensure that
1) Vertical disc lift check valves should be installed on vertical pipes. Horizontal disc lift valve should be mounted on horizontal pipes.
2) The media flow direction should be consistent with the arrow direction marked on valve body.
3. When operating the pipe valve, do not make it bear weight in pipeline. Large check valve (non return valve, reflux valve or one way valve) should have independent support to ensure that the valve will not be affected by pressure from pipe system.

Maintenance
1. For check valves that are not to install temporarily, they should be stored in dry and ventilated room, side flange of the flanged valve must be sealed.
2. The valve for long-term storage should be checked regularly. The surface of the valve must be clear of dirt and coated with anti-rust oil.
3. The following conditions of check valve should be inspected regularly after installation:
1) Wear pattern of sealing surface
2) Wear pattern of rotary rocker
3) Dirt accumulation between the inner chamber of the valve body and sealing surface
4. Sealing performance test should be implemented after every maintenance and assembly of check valve (non return valve, reflux valve or one way valve).

Payment, Package, Transportation & Warranty
1. Products can be paid by T/T, D/P, D/A, L/C, and so on.
2. Standard exporting wooden cases are employed for packaging.
3. Items are transported by air, sea or railway.
4. All our pipe valves have 18 months warranty.