How to Select a Right Sanitary Check Valve?
The sanitary check valve is made of imported SUS304 and 316L, which can meet the special requirements of various mediums in the field of food and biological pharmacy. Its smooth, seamless, and automatic emptying handicraft fluid passage is also very suitable for steam and local cleaning.
Sanitary class check valves can be classified according to service.
* Swing sanitary check valve
The disc of the swing check valve is disc-shaped and rotates around the axis of the seat channel. The flow resistance of the valve is smaller than that of the lift-type check valve because of the streamline of the inner passage of the valve, so it is suitable for large diameter occasions with low flow rate and in constant flow. However, it is not suitable for pulsating flow, and its sealing performance is not as good as the lifting type.
* Lifting sanitary check valves
The upper part of the disc and the lower part of the cover of the lifting sanitary check valve are processed with guide sleeve slips, and the guide slips of the disc can be lifted and lowered freely within the guide slips of the valve cup. When the medium forward flows, the disc by the medium thrust opens; when the media stop flow, the disc by the vertical landing on the seat, thus preventing the media countercurrent effect.
* Butterfly sanitary check valve
Butterfly sanitary check valves are those in which the disc rotates around the pin in the seat. The butterfly sanitary check valve is simple in design and can only be installed in horizontal piping and is poorly sealed.
* Piping sanitary check valve
Piping sanitary check valves are valves in which the disc slides along the center line of the valve body. The piping check valve is a new kind of valve, and it has many advantages such as its small size, lightweight, and good processing technology, which is one of the development directions of the check valve. However, it has a slightly larger fluid resistance coefficient than a swing check valve.
Then how to select the right sanitary check valve for you? Let’s see the advice below.
Check valves for incompressible liquids
Sanitary check valves for incompressible liquids are selected primarily for their performance in closing without the possibility of an unacceptably high impact pressure resulting from a sudden closure due to backflow.
Sanitary check valves for compressible liquids
Although check valves are used for incompressible fluid lines to minimize disc impact, they can be selected according to similar selection methods for incompressible fluids using check valves. However, the impact of compressible media can also become considerable for very large pipelines.
Check valves for compressible liquids may use a speed reducer if the range of media flow is large. The device works during the entire movement of the closing member to prevent rapid and continuous hammering on its end.
Determination of sanitary check valve dimensions
Check valves shall be sized so that normal fluid keeps the shutoff open steadily. For the maximum shut-down time, the check valve should close as soon as possible after the downstream medium begins to slow down. In order to size the valve in this case, the valve manufacturer must provide data for the selected size. In this way, it should be possible to find the valve size at a given flow rate when the valve is fully open.
Selection of sanitary check valve types
* For high-pressure check valves below DN50mm, vertical lift check valves and straight lift check valves should be used.
* For low-pressure check valves up to DN50mm, butterfly, vertical lift, and diaphragm check valves are recommended.
* For high-pressure check valves with DN greater than 50mm and less than 600mm, swing check valves are recommended.
* For DN greater than 200mm, less than 1200mm in the middle, and a low-pressure check valve, it is appropriate to choose a non-wear spherical check valve.
* Butterfly and diaphragm check valves should be used for low-pressure check valves with DN greater than 50mm and less than 2000mm.
* Slow closed swing check valve and slowly closed butterfly check valve should be used for piping with low or no water impact.
