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Installation Instructions for Series CK and CKM Diaphragm Check Valves


Series CK and CKM check valves will open when forward pressure is applied, and when properly installed and used within the recommended ranges of pressure, temperature, and chemical compatibility. The ultimate determination of material compatability is previous successful use in the same application.

Caution: Plastic materials will degrade in ultraviolet (UV) light or sunlight.

Caution: Polypropylene and PVDF (Kynar) often look similar. Do not install in your system if you are not sure.


The check valve will operate mounted in any position. Be careful to install the valve in the correct flow direction.

Threaded Connections: A suitable thread sealant (ex. PTFE tape) should be applied to male tapered threads to assure a "leak-tight" seal. The assembly need only be made "hand-tight" followed by a quarter (1/4) turn with a strap wrench. Do not over tighten or use pipe wrenches on plastic pipe and components.

Caution: PTFE tape will "string" as pipe threads are joined. Loose "strings" could lay across the seating surface and prevent the check valve from completely closing. To avoid this problem, clean out the old tape, and do not apply tape to the first thread.

Caution: Connections should be made only to plastic fittings; metal pipe should only be installed with an intervening plastic nipple. Metal pipe and straight threaded pipe tend to cut, stretch, and distort the plastic bodies, which could result in cracking or leaking over time.

Non-Threaded Connections: For solvent cementing or heat fusion, follow instructions supplied with the cement or fusion equipment, or contact your distributor.


Plast-O-Matic recommends keeping a spare diaphragm available for repairs. Seal life will vary in applications due to cycles, temperatures, pressures, chemicals, and concentration. Based on the application, a periodic inspection and maintenance plan should be established.

CKM cut-away

CKM050 ( 1/2 " ) CKM ( 3/4" & 1" ) CK ( 3/4" & 1" )
1021B 4054B 0721B Buna Diaphragm
1021EP 4054EP 0721EP EPDM Diaphragm
1021V 4054V 0721V Viton Diaphragm


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Plast-O-Matic Valves, Inc.
1384 Pompton Avenue
Cedar Grove, NJ 07009 USA
Voice: (973) 256-3000
Fax: (973) 256-4745


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