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Category: Check Valves

Check Valves: Pumping's One-Way Street (Part 2)


Brass Spring Assisted Check Valve

Last time, we talked about the benefits of check valves in stopping backflow. The benefit is simple to explain. You don’t want contaminants to back up into the line, creating problems.

That blog post focused on swing check valves, which are probably the simplest design of check valve. Put a doorway in the middle of a valve that closes due to gravity and you get the idea behind a swing check valve. With low opening – or “cracking” – pressures, swing check valves function admirably in many situations.

There are a couple of drawbacks to that easy-opening design, however. You are more likely to have excessive wear from the door slamming back into place, especially in a system with pulsating flows. And you cannot install them vertically

Spring-assisted in-line check valves, also known as spring-check valves, vertical check valves, nozzle check valves or silent check valves, need a little more pressure to open. Depending on the spring, it could take 1, 5, 15, 100 or 200 lbs. of pressure to “crack” the valve and allow flow through.

The DuraChoice Brand Valves on DirectMaterial.com crack at 5 psi, in comparison to that company’s swing check valves, which open at 0.5 psi.

A spring-assisted in-line check valve uses a disc fitted against a valve seat and pressed into place by a spring. That spring keeps tension on the disc until the pressure is great enough to push it back. That allows water to flow in one direction.

Because the spring is a constant pressure, it closes the valve as the pressure lessens. That means that the disc has a shorter distance to travel to close off the valve, so flow is shut off quickly and tightly. The quick closing time helps prevent pressure surges in the line which could cause damage to the plumbing.

That quick and quiet closing action is where the valve gets the name “silent check valve.”

Spring-assisted check valves also have the benefit of being installable vertically, horizontally or at any angle, meaning they are more versatile in some situations.

We sell spring check valves in brass and stainless steel, as well as the stainless steel filters which turn the check valves into foot valves for straining particulates.