Diaphragm Check Valve Featured Products A1172 and A1173

These low pressure plastic diaphragm check valves are durable and economical

Color rendered 3D CAD models of A1172 and A1173 featured diaphragm check valvesAbout the featured miniature diaphragm check valves
Our featured check valves are the compact A1172 (blue) and A1173 (black) plastic diaphragm check valves. They are designed for vacuum and low-pressure systems and only need very low pressure differences to open or close.

The valve bodies are made of quality heat stabilized Nylon resins. They are manufactured in the US using automotive grade component molding and ultrasonic welding production techniques. Learn more about how ultrasonic welding works, what it is and why it is used.

Suitable applications
These check valves are part of the ISM single barb CV series of diaphragm check valves. They are used in a wide variety of applications. Learn more about plastic diaphragm check valves and their uses.

A1172 and A1173 specifications

An exploded view of an ISM modular check valve. Click here to go to a landing page where you can get more information about these valves.

Modular Check Valves

We've taken spring-loaded check valves to a whole new level. Mix and match imperial and metric connections. Watch the video.

A play button for a video about ISM's modular check valves. Click here to go to a landing page where you can watch the video.

  • 1/4" barb size on both inlet and outlet ports
  • Semi-rigid barb style
  • Cracking pressure is about 0.18 psi
  • At 3 psi back pressure, leakage is no more than 10 cc per minute
  • Recommended operating temperature range is about -30°F(-34°C) to 210°F(99°C)
  • Air flow capacity is between about 2.7 to 6.4 standard cubic feet per minute (SCFM) estimated
  • Water flow capacity is between about 0.8 to 1.4 gallons per minute (GPM) estimated
  • Maximum recommended operating pressure is about 50 psi (344.7 kPa)
  • Most efficient at differential pressures between ½ psi (3.4 kPa) and 15 psi (103.4 kPa)
  • Valve bodies are made of heat stabilized polyamide (Nylon) 66
  • Free floating disc diaphragm check valve design
  • Available in two different diaphragm material options
    • A1172 Fluorosilicone (FVMQ)
    • A1173 Epichlorohydrin (ECO)
  • Not for use with oxygen

Learn more about the chemical compatibility of nylon.

The flow coefficient (CV) for these diaphragm check valves is estimated to be about 0.13. Flow coefficient is a number generally used to compare flow through valves. The higher the CV, the greater the flow. Testing samples in actual system conditions is recommended. Sample testing will provide accurate actual gas or liquid flow rates. Learn more about flow and the flow coefficient.

What is SCFM?
Standard Cubic Feet per Minute (SCFM) is a measure of the volume of air or gas flow. “Standard” is intended to imply that this flow rate is measured under standard conditions. Standard conditions for air or gas are assumed to be about 14.7 psi (101.4 kPa) and about 68°F (20°C). Learn more about SCFM.

About fluorosilicone and epichlorohydrin elastomers or rubbers

Fluorosilicone (FVMQ)

  • Very broad service temperature range: -70°F (-56°C) to +350°F (176°C)
  • Poor resistance to gas permeation
  • Very good oil and fuel resistance
  • Low chemical reactivity

Epichlorohydrin (ECO)

  • Broad service temperature range: -30°F(-34°C) to 250°F(121°C)
  • Very resistant to gas permeation
  • Very good oil and fuel resistance

Epichlorohydrin elastomer or rubber is widely known as DuPont™ Hydrin®. It is also called polyepichlorohydrin rubber or epichlorohydrin copolymer.

Learn more about elastomers and rubbers as well as the chemical compatibility of elastomers.

Why are plastic diaphragm check valves so useful?

  • Activated by very low differential pressure
  • Economic
  • Excellent durability and long life
  • Silent operation
  • Install in any position*

*Tips to remember about installing the A1172 and A1173 free-floating elastomeric disc diaphragm check valves:

  • “VAC” is embossed on the downstream or outlet port side
  • Check valves are one way valves and must be correctly oriented in the direction of flow
  • These check valves need a back pressure to close
  • They depend on gravity to help close them in some low flow applications
  • High viscosity or high specific gravity liquids may cause them to malfunction

Learn more about how diaphragm check valves work.

Semi-rigid, automotive or hard-line barb style
This type of barb design is intended for use with semi-rigid plastic tubing. It can also be used with flexible tubing in low pressure applications, about 50 psi (345 kPa) or less. These barbs generally expand tubing to about 20% more than the actual inner diameter of matching tubing, which provides very good pull-off and blow-off resistance. Testing is recommended.  Learn more about barbed connector design and function.

As always, ISM offers samples to our customers as a way to assist their testing and decision-making. These can be requested when browsing our catalog.

Has the selection of diaphragm check valves complicated making the best choice for an application? What specifications were the most or least critical? Help us by telling others what you learned.

Have any questions about plastic diaphragm check valves and their use in flow control components? If so, send me an email - steven.williams@industrialspec.com. You can also ask questions using the comments section below.


Steven C. Williams headshot March, 2018.

About the author
Steven C. Williams my LinkedIn profile link button.
Steven C. Williams, BS, is the technical writer and an inbound marketing specialist at Industrial Specialties Manufacturing (ISM), an ISO 9001-2015 supplier of miniature pneumatic, vacuum and fluid circuitry components to OEM's and distributors all over the world. He writes on technical topics related to miniature pneumatic and fluidic components as well as topics of general interest at ISM.       

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