Check Valves in Thermoplastic Materials

Check Valves are used to prevent back flow in pipe lines.  The four distinct designs; ball style, plug style, diaphragm style and wing styles each have their own place in process systems.  A new design cone shape is a hybrid of the ball check to allow for higher flow rates and offer positive sealing.

Ball Check Valves - Use a solid ball and gravity to form a seal against a rubber seat.   This style requires mounting in a horizontal position or spring assistance.  Offers best value in most cases.  1/2" - 4".

Wing Style Check Valves - Plates (wings) swing with the flow of liquid to offer low pressure drops and then swing back and seal on an internal surface upon reverse flow.   Require low back pressures to seal.  See below.

Diaphragm Style Check Valves - Uses an elastomer diaphragm that is in a normally closed position.  This provides for positive sealing at low pressures with out the use of springs or gravity to close.  See Below.

Plug Style Check Valves - Uses a sliding plug to prevent backflow.  Plug may depend upon gravity or spring assist.  See Below.

gf-360-A.jpg (5655 bytes) Ball Check Valves

Good flow characteristics.  Ball (A) is lifted by solution movement - Seats against elastomer (B) when flow stops to prevent back flow.  O-ring seals (D) at end connectors (C) provide easy installation and service.  

  • PVC or CPVC
  • 3/8" – 2" with union connectors
  • EPDM or VitonŽ Seals
  • Solvent cement socket, NPT threads
  • Available Silicon-Free (contact KTH Sales)

Cone Shape Check Valve - Hybrid Check Valve-  Type 561 & 562

Provides good flow characteristics with positive sealing.  Cone seals into the elastomer seat to provide a bubble tight seal even with low back pressure.  Type 562 provides a 304SS or optional coated spring to provide closing without limits.

  • PVC. CPVC, polypro, PVDF
  • 3/8" – 4" with union connectors
  • EPDM or FPM Seals
  • Solvent cement socket, NPT threads
  • Spring assist if required

      Download data sheet 

Diaphragm Check Valves - CKM Series Check Valves - 1/2" through 1"


  • Self sealing diaphragm is not dependent on gravity, reverse flow, or pressure to seal.
  • No internal sliding parts to bind, rotate, or chatter.
  • Low diaphragm opening pressure - 1 to 1.5 PSI.
  • Smooth internal design minimizes cavitation and pressure loss.
  • Union nut simplifies valve installation.
  • Low price - yet designed to highest industrial standards.
  • Choice of PVC, glass filled polypropylene, PVDF , TeflonŽ. and CPVC 
  • VitonŽ or EPDM diaphragm
  • Note PVDF in 1/2" only.
  • Note:  Teflon - 3/4" and 1" only.

           Bulletin in PDF format - download

OEM Specials - We will consider modification of the above valves to meet special needs.  An example would be a spring in the CKM to increase the opening force to 5 PSI.  Contact KTH Sales with your special requirements.

Pom-ckd.jpg (5819 bytes) CKD Series Check Valves - 1/4" and 1/2"


  • Elastomer disc for quiet operation
  • Low pressure for opening and 1/2 PSI for closing
  • Choice of PVC, polypro, PVDF or TeflonŽ bodies.
  • VitonŽ or EPDM elastomer
  • Compact size: 1 1/2" diameter x 2 5/8" long
  • Note:  Cv - 1/2" = 1.0, 1/4" = 0.5
Pom-cks.jpg (7386 bytes)          CKS Series Check Valves - 1 1/2", 2" and 3"


  • Self sealing check valve is not dependent on gravity, reverse flow, or pressure to seal.   May be mounted in horizontal or vertical pipeline.
  • Low opening pressure - 1 to 1.5 PSI.
  • TeflonŽ PFA coated spring for bubble tight closing
  • PVC construction - Buna, VitonŽ or EPDM O-ring
  • 1 1/2",  2" or  3"
  • True Union end connections
  • Consult regarding CPVC, polypro or PVDF
  • Note:  Cv for 1 1/2" and 2" = 45, 3" = 82

    Download Bulletin for CKS Check Valves  

Spears - Butterfly Check Valves


  • Size 2" to 12" 
  • Quick Response Shut-off In Any Position
  • Chemical Resistant PVC and CPVC Construction
  • Field Replacement Flex-Seal - Choice of Reinforced EPDM or Viton

  Bulletin in PDF format - Download

gf-304.jpg (10932 bytes)
additional details

TYPE 304 – Y-Check Valve – PVC Translucent Body

With a clear body, the movement of the check will indicate flow.  Excellent flow characteristics. Minimum pressure loss. Mount horizontally or vertically. The soft seat (4) and weight loaded (5) check  offer excellent performance.  Efficient at low working pressures.  

  • ˝" through 3"
  • EPDM or FPM Seals
  • Solvent cement spigot end connection

Pom-vbm.jpg (8579 bytes)

VB and VBM Vacuum Breakers - 1/2", 3/4" and 1"


  • Choice of PVC, glass filled polypropylene, PVDF or TeflonŽ.
  • VitonŽ or EPDM diaphragm
  • 1/2", 3/4" or 1"
  • Use for anti-siphon on piping systems
  • Use for vacuum relief of tanks
  • Identical to CKM except with dusk cap on inlet
  • Allows air in through the dusk cap when vacuum reached 3 feet of liquid column.
  • NEW - VKM Series Vacuum Breaker - 1 1/2", 2", 3" -- similar to CKS valve with a dust cover - 

      Download data sheet 

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