Frequently Asked Questions

Pinch Valves

What is a pinch valve used for?

            A pinch valve is used for both isolation and control of various processes. Most commonly abrasive, scaling, aggressive and plugging slurries. This is a achieved by pinching a rubber sleeve internal to the valve body.

How does a pneumatic pinch valve work?

A pneumatic pinch valve utilizes a pneumatic cylinder to pinch a rubber tube. The air pressure is added to either side of the cylinder open or closes the valve. The added air pushes the piston of the cylinder in the desired direction of travel. This piston connects to a pinch bar which pinches the rubber tube of the valve.

How does a manual pinch valve work?

A manual pinch valve utilizes a handwheel which is turned to either open or close the valve. As the handwheel spins, the pinch bars are either pulled closer together or further apart depending on the direction. This action of the pinch bars pinches the rubber tube and controls the process media.

How does a hydraulic pinch valve work?

A hydraulic pinch valve utilizes a hydraulic cylinder to pinch a rubber tube. The hydraulic fluid pressure is added to either side of the cylinder to open or close the valve. The fluid pushes the piston of the cylinder in the desired direction of travel. This piston connects to a pinch bar which pinches the rubber tube of the valve.

How does a gear box pinch valve work?

A gear box is added to a pinch valve when direct manual actuation cannot be achieved (the rim pull is too high) in a reasonable manner . The gear box reduces both the torque required to actuate the valve as well as the amount of turns required to open/close the valve.

How does an electrically actuated pinch valve work?

An electrically actuated pinch valve uses an electric motor to control the pinch bars and thus open and closes the valve. These types of actuators can be used for both open/close applications and modulating applications for control. Typical manufacturers of these actuators are Auma, EIM, Rotork, Limitorque, etc.

What types of pinch valves are there?

Pinch valves are typically broken into two categories: Open/Close (On-Off) or Modulating. This depends on the application and the objectives of the valve in said application. Additionally, they are categorized by the type of actuator used to open and close the valve (Eg. Manual, Electric, Hydraulic, Pneumatic)

What is a throttling valve?

            A throttling valve restricts the flow through a pipeline by restricting the orifice by which the process can travel through. This is typically used to control the flow from one piece of equipment or process to another. 

What are the advantages of a pinch valve?

A pinch valve has many advantages especially in abrasive, scaling, plugging, and aggressive slurries. These types of processes tend to have high abrasion and wear on the equipment attached to them. The primary advantage of using a pinch valve is that the internal rubber tube is replaceable and designed to accommodate difficult applications. By only needing to replace the tube, the owner/operator of the pinch valve can lower their ongoing operational costs by not having to replace entire valves. 


Air Valves 

How does an air release valve work?

Air Valves utilize a system of floats that will allow air/gas to escape a pipeline, but then close when water arrives at the air valve.

Where does the air release valve go?

Air Valves are placed at apex points in the profile of a pipeline, inside plants and pump stations near pumps, at the top of tanks, anywhere it is desirable to remove excess air from a pressurized water piping system.

What is the function of an air valve?

Modern air valves provide four functions:

1)     Vacuum Protection – when pipelines are draining

2)     Large Air Volumes out – when filling the pipeline

3)     Pressurized Air Release – when pipelines are full of water and flowing

4)     Surge Alleviation – control and prevention of potentially damaging pressure spikes

What is an air release valve?

Air Valves are devices that transfer air / gas that is present inside a pressurized conduit from pipeline to atmosphere and from atmosphere back into pipeline to allow for water to flow efficiently.

What is the function of air valve? 

To control the transfer of air / gas from pipeline to atmosphere and back to facilitate the flow of water in a pressurized conduit as efficiently as possible.

Where are air valves installed?

Primarily at apex points along the profile of the pipeline, between pumps and control valves, as well as after check valves on header piping before exiting the pump stations.

What is a vacuum break valve?

A Vacuum Break Valve is designed to allow the transfer of air from atmosphere to pipeline any time the pressure within the pipeline falls below atmospheric pressure outside the pipeline.

How does a vacuum breaker valve work?

A vacuum breaker is closed anytime the internal pressure within the pipeline is greater than atmospheric pressure outside the vacuum breaker valve. The vacuum breaker opens when the internal pressure inside the pipeline is less than atmospheric pressure, allowing air to be drawn into the pipeline.

What does a vacuum relief valve do?

Same as the vacuum breaker.

What causes a vacuum breaker to leak?

Seal failure is the most common reason. Usually there is an obstruction of some kind that prevents the seal from doing its job.

What is the difference between air release valve and air vacuum valve?

Air Release valves allow air to move from pipeline out to atmosphere. Air / Vacuum valves allow for both air to exit the pipeline as well as allow air to re-enter the pipeline.

What is a combination air valve?

Combination air valves allow for both large volumes of air to exit the pipeline during filling and then there is a combination of a smaller air valve to allow for pressurized air release when the pipeline is full and operating.

Why air valves are needed in water applications?

There are many known troublesome issues with the failure to properly control the transfer of air from pressurized pipelines out to atmosphere and back.   Because water is essentially not compressible and air / gas is greatly compressible, this sets up the potential for the air to act like a “spring” which can lead to tremendous pressure surges and resulting, destructive hammer effects. 


Knife Gate Valves

What is a knife gate valve used for?

            Utilizing a gate or blade is ideally used to cut through heavy liquids and slurries. Slurry Knife Gates are designed to work in harsh environments, are easy to actuate and tend to be less expensive to produce. 

How does a knife valve work?

            A knife gate valve has a blade that is moved up and down via an actuator to block a port on the valve body. Typical types of actuators include Manual Handwheels, Pneumatic Cylinders, Hydraulic Cylinders and Electric Motors.

When would you use a gate valve?

            A knife gate is used for isolation of a pipeline or piece of equipment on a pipeline. It is not recommended to use a knife gate for throttling and control services, only open/close or on/off applications.

What is a knife gate?

            A knife ate utilizes a sharp, beveled edge and designed to cut through the process media. The benefits of a knife gate are their small face-to-face dimensions, ease of actuation and availability.

How does a knife gate valve work?

            A knife gate works by moving a blade or gate up and down to open or close a port on the valve body. This movement is used to allow or block flow in a pipeline.

What are different types of gate valves?

Gate valves are typically divided into two types: Parallel or wedge-shaped. The parallel gate valve use a flat gate between two seats and is more commonly referred to as a knife gate. A wedge shape gate uses two inclined seats and a slightly mismatched inclined gate.