Taking time to size a valve correctly saves you time, money and yourself a headache!
Picking the right size leads to performance
Our goal is to find the valve with the best control for your specific application. The Cv, or coefficient of flow of the valve, plays a big part in the valve’s performance. A valve that is sized correctly has accurate flow control, lasts beyond its expected life span and does not leak.
All you need to size a valve is the GPM and pressure drop! Calculate the Cv with this equation:
CV = coefficient of flow, GPM = flow rate in gallons per minute and ∆P = differential pressure
Selecting the wrong size results in complications
When a valve is too small, you won’t get enough flow, and the system will be forced to compensate by raising the head pressure of the pump. This causes higher differential pressure across your valve. The sudden drop in pressure causes cavitation and affects the life of the valve. The vibration and turbulence wears out the seals, which results in leaks.
Did you know most engineers oversize a pump by as much as 15% to cover for this type of mistake?
That doesn’t mean you should be lax when sizing your valve though!
When a valve is too big, the main problem is controllability. The system has to compensate with a balance valve. You may see close to 50% reduction in flow, depending on how oversized a valve is, which means if you are modulating the valve, the control loop will have to drastically change. This will wear out the valve and actuator prematurely, increase flow above desired rate and result in poor heat exchange.
Working with Kele is a smart choice
When you need help selecting the correct valve for your application, feel free to lean on Kele by visiting Kele.com or calling 888.584.6165. We have all the major brands, all in one place. Save time, money and yourself a headache today!
Don’t make your work harder than it has to be! Check out Control Valve Central to find all the major brands, all in one place!
