CVSF Series Valved Suction Strainers – New Products

Last updated on August 30, 2019

One-way foot valves with built-in 40 mesh strainers prevent coarse particle contamination

The lineup of the CVSF series valved suction strainers from left to right - push-in white nylon, hose barbed gray PVC, male NPT thread black Kynar and female NPT thread white polypropylene.About the CVSF valved suction strainer
Our featured new product is the CVSF series of valved suction strainers, also called suction filters or foot valves. The design of these valved strainers is a spring loaded ball check valve combined with a 40 mesh stainless steel domed strainer.

The CVSF series strainers come in Kynar, Nylon, polypropylene and PVC body material options. 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.

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.

CVSF series features and specifications

  • 40 mesh (about 380 to 425 microns) stainless steel suction screen
  • Kynar (black), Nylon (black and white), polypropylene (black and white) and PVC (gray) body material options
  • Buna-N, EPDM and fluoroelastomer (Viton®) seal options
  • 302 stainless steel, Hastelloy® and “no spring” spring options
  • 302 stainless steel spring cracking pressure options: 1/3, 1, 3, 5, 7, 10 and 12 psi
  • Hastelloy® spring cracking pressure options: 1/3, 1, 3, 5 and 12 psi
  • Maximum recommended operating temperature is about 140°F (60°C)
  • Maximum recommended operating pressure is about 125 psi (861.8 kPa)
  • Seat area open diameter is 0.25 inches (6.35 mm)

Learn more about the chemical compatibility of materials typically used in miniature flow control components.


CVSF series connection options

  • 1/8”, 1/4” Male NPT Threads
  • 1/8” and 1/4" Female NPT Threads
  • 1/8”, 1/4", 5/16”, 3/8” and 1/2" Hose Barb
  • 1/4" and 3/8” Push-In

The flow capacity of these valved strainers is based on a seat area open diameter of 0.25 inches (6.35 mm). Flow rates can best be determined by flow testing in actual operating conditions. Flow rates are heavily influenced by system pressure. Learn more about flow and the flow coefficient.


Suitable foot valve applications

  • Suction lines for well pumping systems
  • Inexpensive and reliable priming for single centrifugal pumps
  • Provide positive seals at low or high pressures without slamming
  • Prevent pump pipe columns from draining when the pumps shut down
  • They are also widely used in all kinds of pneumatic systems

Foot valve suction strainers or foot valves are frequently installed at the bottom of pump suction lines.

Learn more about spring loaded check valves and their uses.


What is a strainer and what makes it different from a filter?
Filters and strainers both protect downstream equipment from the damage or malfunction from loose particles. A filter separates solids from liquids or gases by directing flow through a screen or porous material that removes particles above a certain size. A strainer removes unwanted large particles from liquids with a screen, usually when the liquid is being pumped from a lower level or well. In general, strainers are designed to provide less resistance to flow than filters do.

The strainer section of CVSF valved suction strainers removes particles that can either damage a downstream pump or cause the check valve itself to malfunction.

*Important tip: Use only high quality, durable valved suction strainers like the CVSF series. After installation, they may be difficult to inspect or repair.


About Buna-N, EPDM and fluoroelastomer (Viton®) rubbers

Buna-N (NBR, nitrile rubber)

  • Service temperature range: about -10°F (-23°C) to +250°F (121°C)
  • Poor resistance to gas permeation
  • Very good oil and fuel resistance
  • Low chemical reactivity

EPDM (EP, EPR, ethylene propylene diene)

  • Service temperature range: about -50°F (-45°C) to +300° F (149°C)
  • Fair to good resistance to gas permeation
  • Poor oil and fuel resistance
  • Good resistance to ketones, ordinary diluted acids and alkalies
  • Outstanding ozone resistance

Fluoroelastomer rubber (Viton®)

  • Service temperature range: about -10°F (-23°C) to 375°F (191°C)
  • Good to excellent resistance to gas permeation
  • Resistant to corrosives, solvents and oils at elevated temperatures
  • Outstanding ozone resistance

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


Why are the CVSF valved suction strainers or foot valves so useful?

  • Economic
  • Silent operation
  • Easy to install and service
  • Excellent durability and long life
  • Material options accommodate most chemical compatibility


Tips to remember about installing CVSF valved suction strainersA close-up view of a cutaway section of the CVSF spring loaded check ball valve components

  • Check valves are one way valves
  • Only the no-spring versions of these strainers may need a back pressure to close
  • High viscosity liquids may cause no-spring valved strainers to malfunction under certain conditions
  • Spring loaded or spring assist valves do not depend on gravity to help close them in low flow applications

Learn more about how spring loaded or spring assist check valves work.


NPT tapered pipe thread connections
The most common tapered pipe thread found in the US is NPT, American National Standard Taper Pipe Thread. Tapered pipe threads are used for piping and fittings that carry liquids and gases. When installed properly, tapered threads help create seals that are gas or liquid tight. The male and female threads compress and wedge themselves together. As a result, these connections are strong and leak resistant. Learn more about tapered pipe threads.


Hose barb connectionsA cutaway of flexible tubing showing how it interacts with a hose barb to create a pull-off and blow-off resistant seal.
Hoses barbs are intended for use with flexible plastic tubing. The barb ridges expand the tubing that then tries to relax to its original size on the backside of each barb ridge. This provides the tube-to-hose-barb seal as well as very good pull-off and blow-off resistance. Testing is recommended. Learn more about barbed connector design and function.


Push-in connections
Push-in connectors are leak resistant because they use built-in O-ring seals. This type of connector also has built-in metal teeth that grip the tubing. In order for a push-in connector to function properly, the tubing needs to be soft enough for the teeth to grip but not so soft that the tubing bends instead.

Get more info about the CVSF Series Valved Suction Strainers

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 selecting the right valved suction strainers complicated making the best choice for your new system design or MRO application? What specifications were the most or least critical? Help us by telling others what you learned.

Have any questions about valved suction strainers or foot valves and their use as flow control components? If so, send me an email - 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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