Modular Check Valves - CVIS Series

ISM’s Most Customizable Check Valve Product Line 
The new CVIS Series Modular Check Valves are our most customizable check valve product line. Easily switch internal and housing components to fit your application requirements.

Product Features and Benefits

  • Single barb design
  • 4 O-ring seal material options
  • Multiple cracking pressures
  • Locking tabs for high pressure applications
  • Both imperial (inch) and metric combinations
  • Various sizes of barb and push-in connections
  • 1/8” BSPP female threads fit both BSPT
  • (ISO 7-1 R) and BSPP (ISO 288-1 G) male threaded connections
  • 1/8” BSPP female threads fit both BSPT (ISO 7-1 R) and BSPP (ISO 288-1 G) male threaded connections

CVIS Series Specifications

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Modular Connection Check Valves, with internal O-ring sealing, utilizing a spring loaded floating poppet to allow flow at a predefined cracking pressure.

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C V I S series modular check valve technical specification sheet and drawing samples.

Specs, Drawings and 3D Models

C V I S series modular check valves: red color thread by barb, blue color barb by barb and natural color barb by thread.


Modular check valves product overview P D F front cover.

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Full Specifications

Valve Body (Housing) Material

  • Glass-filled polypropylene – FDA FR21 compliant

Cartridge Body (Housing) Material

  • Polypropylene – FDA CFR21 compliant

Poppet Material

  • Polypropylene – FDA CFR21 compliant

Spring Material

  • 302 Stainless Steel

O-ring Material Options

  • Buna-N (nitrile, NBR), EPDM, Silicone or Viton®

Maximum Inlet Pressure

  • 75 psi (5.17bar) @ ambient 21°C (70°F)

Cracking Pressure Options

  • No spring, 0.1, 1/2, 1, 2, 3, 4, 5 or 10 psi

Inlet and Outlet Connection Options

  • Hose Barbs – 1/8”, 1/4", 5/16” and 3/8”
  • Push-In – 4mm, 6mm and 1/4"
  • Threaded – 1/8” Female BSPP (ISO 288-1 G Series, ISO 7-1 Rp, DIN 259, JIS B 0203)

Mounting Style

  • In-line

Operating Temperature

  • 5°C (41°F) to 50°C (122°F)

Storage Temperature

  • -50°C (-58°F) to 50°C (122°F)


  • Min 100,000 cycles – Maintenance free

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Regulatory and other information

Regulatory Compliance

  • FDA CFR21 compliant
  • RoHS

Clean Room Manufactured

  • Not clean room manufactured

Check valves are generally used in an application that requires free flow in one direction, indicated with an arrow on the check valve, and no flow in the opposite direction.

They can also be useful as bypass valves allowing flow around other circuitry components such as needle valves which would restrict the flow in both directions.

Threaded Connections
Using BSPP male with BSPP female threads requires an O-ring gasket or sealing washer for a leak tight seal. Using BSPT male threads with BSPP female threads requires an appropriate thread sealant to prevent leaking.

A PTFE-based (Teflon™) pipe thread sealant is generally recommended for plastic threads but beware of overtightening. PTFE-based sealants, and thread sealants in general, make it easier to overtighten and potentially deform plastic threaded connections.

BSPP, British (Whitworth) Standard Pipe Parallel, is currently considered an obsolete pipe thread standard. While "BSPP" is still commonly used to indicate this specific type of pipe thread, the standard it is based on has been replaced by ISO 228-1.

ISO 288-1 is currently the international standard for interconnecting and sealing pipe ends and pipe fittings using parallel pipe threads. Officially it is called ISO 228-1:2000, "Pipe Threads where Pressure-tight Joints are not made on the Threads: Dimensions, tolerances and designation".

BSPP or ISO 228-1 (DIN 259) threads are also called G series pipe threads. R tapered external pipe threads (BSPT, BS 21, DIN 2999, ISO 7-1, EN10226-1 and JIS B 0203) will mate with G parallel internal pipe threads.

Materials of Construction

Component Materials

  • 302 Stainless Steel Spring
  • Polypropylene Poppet (Plunger) and Cartridge Body (Housing)
  • O-ring Seals: Buna-N, EPDM, Silicone or Viton®

Valve Body (Housing) Options

  • 30% Glass-Filled Polypropylene in Red, Blue or Natural


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What a Modular Check Valve Part Number Means

Prefix – Inlet – Outlet – Cracking Pressure – Seal – Housing Material

Prefix (CVIS)
CVIS is the Modular Check Valve Series prefix. It is the beginning of every modular check valve part number.
     Example: CVIS-18-14-4#-V-BLPP

Inlet and Outlet (CON)
This is an abbreviation that stands for connection type and its size. The inlet is listed first and the outlet second. If both connections are the same, it is only listed once.
See the Specification Codes section below for the connection codes.
     Examples: CVIS-18-14-4#-V-BLPP (1/8” hose barb by 1/4" hose barb connections)
     CVIS-18-4#-V-BLPP (1/8” hose barb by 1/8” hose barb connections)

Cracking Pressure (CP)
This is an abbreviation for the cracking pressure of the check valve. If no CP code is required (no spring option), then no CP code is used.
See the Specification Codes section below for the cracking pressure codes
     Examples: CVIS-18-14-4#-V-BLPP (4 psi cracking pressure)
     CVIS-18-14-V-BLPP (no spring)

Seal Material (SEAL)
This is where the seal material is listed.
See the Specification Codes section below for the seal material codes
Example: CVIS-18-14-4#-V-BLPP (Viton® O-ring seals)

Material (MAT)
This is the abbreviation for the body material and color. All the housings are 30% glass-filled polypropylene. They are available in red, blue or natural polypropylene.
See the Specification Codes section below for the material and color codes
Example:   CVIS-18-14-4#-V-BLPP (blue glass-filled polypropylene body)


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Specification Codes for Modular Check Valves
Connection Codes
• 1/8” HB = 18
• 1/4” HB = 14
• 5/16” HB = 516
• 3/8” HB = 38
• 1/4” Push-In = 14P
• 4mm Push-In = 4MM
• 6mm Push-In = 6MM
• 1/8” Female BSPP = G2F

Cracking Pressure Codes
• No Spring = (no symbol)
• 0.1 psi = .1
• 1/2 psi = .5
• psi = 1
• psi = 2
• psi = 3
• psi = 4
• psi = 5
• 10 psi = 10

Seal Material Codes
• Buna-N = BU
• Silicone = SI
• Viton® = V

Material and Color Codes
• Red Glass-Filled Polypropylene = RPP
• Blue Glass-Filled Polypropylene = BLPP
• Natural Glass-Filled Polypropylene = NPP

More Modular Check Valve Part Number Examples

1/8” Hose Barb Inlet x 1/4” Hose Barb Outlet, 4 psi Cracking Pressure, Viton® Seals, Blue Glass-Filled Polypropylene

1/4” Hose Barb Inlet and Outlet, No Spring, EPDM Seals, Natural Glass-Filled Polypropylene

1/8” Female BSPP Inlet x 1/4” Push-In Outlet, 1/2 psi Cracking Pressure, Viton® Seals, Red Glass-Filled Polypropylene


Product OverviewThis modular check valves product overview provides details on this part series features and benefits, specifications, regulatory compliance and component materials. It also includes a complete description of how to configure a modular check valve part.


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