Check valves are very important in a hydraulic installation and the selection of the right type is very crucial for an effective and safe operation. GEMAK has a selection program in order to define the most appropriate check valve in each case. In general terms there are some special characteristics of each type of check valves, as mentioned bellow:

1. Membrane Check Valves
   They are recommended where the critical time for the surge wave appearance is more than 2sec. The practical explanation of this is the following: if the critical time is less than 2sec the check valve protects the pipeline but not the pump systems which are damaged. This valve type is practically recommended for pipelines with length more than 1200m.
2. Spring Type Check Valve type AS-S/Y-60
   The valve closes in 80/100 sec and the main purpose of its installation is the protection of the pumps from the surge waves. It is recommended for all types of networks unless the critical time is less than 40/100sec.
3. Flat Check Valve
4. Non Return and Pump Protection Valve AS-A/Y-40 S-A/Y-40
   Closes in 0,23sec. Suitable for short pipelines protecting the irrigation and water supply machinery.
5. Check Valve Diaphragmatic Type AS-A/Y-60

With regulation of the closure and opening speed. It closes rapidly and provides protection to the machinery and the paipeline according to the regulation. Appropriate for pipelines under 400m length.

If the surge wave critical time is less than 0,4sec, please conduct GEMAK, so that we are able to suggest the best and the most effective solution for each case.

6. Check valve with Rubber sealing Disc

suitable for water supply, irrigation and sewage networks

7. Ball type check valve for sewage networks