Sanitary Check Valves- An Overview

January 27, 2014
Sanitary Ball Check Valve

Sanitary Ball Check Valve

This is the third of our posts giving basic overviews of the various sanitary valves commercially available on the market.   Today we going to discuss  sanitary check valves

Principles of operation
Sanitary check valves allow product to flow though it in only one direction.  These are two-port valves, meaning that they have two openings in the body, one for fluid to enter and the other for fluid to exit.  There are various types of check valves used in a wide variety of applications.  There are two basic categories of sanitary check valves, disk type and ball type.  Check valves work automatically and most are not controlled by a person or any external control.  Bodies of check valves are generally made up of plastic or metal.  In most sanitary applications you will find the composition of the valve being 316L stainless steel and are CIP capable if applied properly.  Most have sanitary clamp connections but can be configured with buttweld ends of various other sanitary connections.

One important concept about check valves is the cracking pressure.  Cracking pressure is the minimum upstream pressure at which the valve will operate.  These valves are typically designed for and can be specified for a specific cracking pressure.

Types of Sanitary Check Valves
Ball check valves are valves in which the closing member is a spherical ball.  Some ball check valves contain a spring-loaded ball in order to help keep it shut, most operate by gravity.  Ball type sanitary check valves have a Y body configuration.  The combination of gravity and back pressure forces the ball against the valve seat in the main run of the valve.  When forward pressure is applied the ball is forces up into the Y branch of the valve allowing full flow through the valve.  Normally Y type ball check sanitary valves are used in horizontal lines and are completely drainable. They are commercially available in sizes 1 1/2” through 3”. Ball check valves can be equipped with another type of check valve, an air blow check, to evacuate lines of product or CIP solution with compressed air.

Sanitary Disk Type Check Valve

Sanitary Disk Type Check Valve

Disc type sanitary check valves consist of a straight through body with a valve seat machined into the ID.  A spider insert holds a metal disc that is normally spring loaded to push against the valve seat.  Discs are available with straight metal seats or a metal seat with an o ring seal.  Disk type sanitary check valves can be used in both horizontal and vertical applications.  For horizontal applications, special configuration are available to make the valve completely drainable.  Disk type sanitary check valves are commercially available in sizes 1” through 4”.

There is a variant of the traditional disk type check valve manufactured by Check All Valve that eliminates the valve body entirely.  Instead the valve features fluoropolymer disk assembly that mount in place of a standard Tri-Clamp gaskets.  These are relatively inexpensive and can save a lot of space in tight piping applications.

Considerations When Choosing the Right Sanitary Check Valve

Check All Insert Disk Check Valve

Check All Insert Disk Check Valve

Here are some of our thoughts on choosing the right valve for your application gleaned from applications we have worked with over the years.

  • Thick sticky products can sometimes be problematic with ball type sanitary check valves.  If you have something thick, the ball may lodge itself into the Y branch and not seat properly.
  • With ball checks, you have to make sure you pick the right elastomer ball for your application.  Balls are normally available in Buna, FKM(Viton) and EPDM.  Make sure you pick a material that is compatible with your product.
  • Metal disk type sanitary check valves do not always create a perfect seal.  To ensure you get proper sealing, get one with an O ring seal.
  • Disk type sanitary check valves with have a higher pressure drop.  Because the disk and spider are in the flow path.  Ball type valve have virtually no pressure drop.
  • You can PIG your line through a ball type check valve.  You cannot through a disk type.
  • Disk type check valves have a wider range of springs for greater precision when selecting crack pressure
  • If you are using a disk type valve in a horizontal line, make sure you specify the eccentric model to ensure you get complete drainage.
  • If you need a sanitary check valve in a 1” size, only disc types are available. The same holds true for 4”.

We offer all of different types of sanitary check valves we have discussed above.  We also offer customer variations of these such as jacketed sanitary check valves.   If you have any questions about the offerings or how may fit into your application contact us here at Holland.