The essential guide to check valves
Check valves are a standard component used in many industries and are used to prevent fluid and gas from flowing in the wrong direction. So, just how do check valves work? What type of check valve applications are there? And what are common check valve uses? Continue reading to find out everything you need to know about check valves.
What is a check valve?
Check valves are a type of valve that are designed to prevent or manage the flow of gases, water and other fluids from going in the wrong direction within a system of pipes. Fluid or gas that passes through a check valve can only move one way, and it’s important to minimise or entirely prevent backflow as it can cause contamination or damage equipment, with potentially serious consequences.
Check valves have a number of alternative names, such as:
Non-return valves
One-way valves
Reflux valves
Foot valves
Retention valves
Stop valves
Check valve uses and applications
Check valves are used in pump outlets to keep water moving in the correct direction. One of the most widely used types of water pump, centrifugal pumps, are not self-priming. This means they cannot expel air from their tubes before operation. So check valves keep the water moving until the air within the pump has been separated from the incoming water and expelled.
Check valves can also be used in heating, ventilation and air conditioning (HVAC) systems, especially ones installed in large buildings. A setup like this requires coolant to be pumped through multiple floors. Check valves play an important role in beating gravity to ensure that none of the coolant flows in the wrong direction.
Another application for check valves is to protect drinking water from exposure to other types of water. They’re also used to stop the spread of contaminated water back up the pipe.
Types of check valves
Check valves are available in a wide range of different shapes and sizes for use in standard pipes and industrial pipelines alike. Each type is designed for use in different check valve applications.
Here is a list of the main types of check valves:
Swing check valves
Can be attached to a shaft and move in response to pressure, swinging open as fluid or gas enters and then falling back into place to seal the valve and block reverse flow. Effective in systems prone to pressure surges.
Ball valves
This standard one-way valve design features a ball bearing mounted on a spring that moves up and down in response to pressure within the valve.
Double check valves
Consists of two attached units. Single check valves provide good protection but can be doubled in applications where it’s essential to prevent contamination through backflow. They can, for example, be used in drinking water pipes. The extra valve creates a stronger seal and can act as an emergency back up if the first seal fails.
Lift check valves
These feature a disc mounted on a spring that lifts vertically from the seat of the valve in response to fluid pressure. Its cracking pressure must be sufficient to overcome gravity because backflow will reverse this movement.
Clapper valves
Clapper valves are used in firefighting systems. They feature a hinged gate that opens in the direction of the incoming liquid and closes when there is no forward pressure.
Reverse check valves
These check valves are used in gas lifts to prevent backflow and fluid mixing, as well as to allow pressure to circulate.
Inlet check valves
Used in vehicles to prevent fuel from spilling back out while refuelling.
Non-slam check valves
A variation of the swing type in which the disc can’t slam shut in response to backflow. Instead, a pressure-sensitive spring moves the disc in a smooth motion.
Low-pressure non-return valves
Designed to be sensitive to low-pressure fluid or gas flow that standard models may not handle as well.
Two-way check valves
Specialist types of check valves used in air braking systems.
Check valve suppliers
At BM Engineering, we provide a large variety of different valves and check valves, ranging from ball valves to knife gate valves. Our stock includes products suitable for a number of different applications, industries and systems, and is sourced from the best industrial check valve suppliers in the world. Some of the exceptional brands we supply include Inoxpa, Bürkert, Valsteam and many more.
Our experience as leading check valve suppliers makes us well-qualified to help you with your valve selection, design and sizing for all your industrial valve applications.
If you’d like to speak to one of our technical experts here at BM Engineering, don’t hesitate to contact us on 0141 762 0657 or email us at sales@bmengineering.co.uk.
