There are two basic types of balancing valves - with and without drains. In cooling and heating systems as well as domestic water systems, balancing valves are used for accurate hydronic balancing (distribution of heat flows in the system) in a wide range of applications. The desired flow rate can be preset as required. The non-draining option offers valve closure. The drain version has a drain option in addition to closing.

Ian Noble is the Global Business Line manager for the Crane range of Engineered Check valves, working within the Crane Process Flow Technologies (CPFT) business segment. Crane Process Flow Technologies segment is a global provider of highly engineered products and systems, serving chemical, petrochemical, pharmaceutical, water and wastewater and general industrial market among others.

John McIlroy has worked in manufacturing for more than 30 years, including 15 in the valve industry. He has had roles in check valve technical sales, applications engineering and manufacturing. McIlroy’s current role of application specialist for Crane Engineered Check Valves has a wide scope from direct customer support, resolving immediate system issues where the correct check valve can be a solution, to technical presentations around the application of check valves within industries like oil and gas, petrochemical, hydrogen production, LNG and renewable energy.

Check valves are self-actualizing devices that respond to both pressure and flow changes in a piping system. #knowyourvalves #gate-globe-check

While presenting in a recent VMA Valve Basics 101 Course in Houston, I found myself in a familiar role: explaining solenoid valves (SOVs) to attendees. (I work with solenoids so much that one VMA member at that conference joked that I needed to be wearing an I Heart Solenoids t-shirt). During the hands-on “petting zoo” portion of the program, which involves smaller groups of attendees, one of the most frequently asked questions I get from people came up: What’s the difference between direct-acting and pilot-operated SOVs, and how do we make a choice?

Simple conventional swing check valves tend to have a very poor response. Under dynamic conditions, relatively long response times are experienced. This yields high reverse velocities resulting in slam and unwanted pressure surges.

As a result of the venturi design, the reduced flow area increases the kinetic pressure and reduces the static pressure allowing the valve to fully open quickly. The spring is selected so that the disc is fully opened and stable against its backstop under normal flow conditions.

When flow is reversed in a pipe, this can cause hydraulic shock waves to pass through (also known as water hammer). This can cause severe damage to equipment in the pipeline if measurements are not taken to prevent this. The introduction of the correct check valve, in a fully closed position during reverse flow can prevent this from occurring and causing severe issues at the site.

The base valve design is available in various body configurations to suit the customers’ needs for industry standards, specification, weight and connection requirements. The majority of axial flow check valves will be sold as flanged.

Central heating systems, water heating systems and cooling systems need to be balanced. Valves are equipped with measuring inserts. Internal threads on both sides of the valve body serve for mounting. The handle is made of durable plastic. Manual balancing valves are manufactured mostly in DN 15 - 50, pressure class PN 20.

When pressure differential between the upstream and downstream side of the valve exceeds cracking pressure of the spring, the obturator will move and allow flow. The flow area of the valve decreases steadily down to the seat diameter; this is the venturi design.

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The primary purpose of check valves is to permit flow in one direction while prohibiting or stopping the flow in the opposite direction. The key point is that the normal resting state of a check valve is the closed position.

Although axial flow check valves can be utilized in a multitude of applications, a growing number of niche sectors the valves have primarily been utilized in the following:

As mentioned, axial flow check valves have an excellent response and are recommended where a high-level performance is essential. As flow decelerates in the pipeline, the forces acting on the disc are reduced, and the spring is able to overcome these smaller forces causing the valve to close. Short displacement of the disc combined with axial spring assistance greatly reduces the response time giving a fast slam-free response with minimal reverse.

The most important thing to remember is that axial flow check valves are specifically designed for fast-reversing systems where backflow is a constant concern.

There are two basic types of balancing valves on offer - with and without drain. In cooling and heating systems as well as in domestic water systems, balancing valves are used for precise hydronic balancing (distribution of heating flows in the system) in a wide range of applications.

Axial check valves are specifically designed for fast-reversing systems where backflow is a constant concern. It is categorized as a non-slam check valve as the valve closes without slamming meaning no excess pressure spikes are created. Most axial flow check valves are spring-loaded, with a single low-mass disc, which facilitates a fast, dynamic response to reduction in flow. Due to having a single disc and spring when the disc is opening, the force is balanced resulting in an even flow.

In the world of low-pressure and low-vacuum relief valves—defined for this article as valves with settings less than 15 psig—there are several different common valve configurations.

Dual plate spring-assisted valves versus conventional swing checks are designed with small plates, which have less inertia than a single thicker disc. Pre-loading with a spring provides a closing force at all angles, thus helping to reduce response time.