What is a Belimo Valve and how is it typically used?

Belimo actuated valves are commonly used in the beverage industry to control coolant flow at distribution points in conjunction with thermostat controllers amongst other applications. There are a wide range of valve types that the actuator controls such as 2-way/3-way ball valves, butterfly valves, globe and diaphragm valves just to name a few. They are a very good alternative to solenoid valves as they are slow closing and can prevent or limit pressure surges and hammering.

Another application, specific to chillers, as opposed to controlling coolant flow for heat transfer is to prevent backflow glycol at the chiller reservoir in the event the process pump stops. These are fail-safe valves where the valves are powered open and return to the closed position if the pump or chiller loses power.

Spring Return actuators utilize an internal spring that drives the actuator open or closed on loss of power. Electronic Fail-safe actuators utilize super capacitors that discharge stored energy to the motor and the actuator is driven open or closed on a loss of power. Non-Spring return actuators stay in their current position on loss of power.

The valves can be full port or standard port. The difference between a standard ball valve and a full-port ball valve is in the size of the ball and bore in relation to the nominal pipe size of the valve. For example, the bore size in a 3/4-inch full-port ball valve is 3/4-inch in diameter, while the bore diameter in a standard ball valve is 1/2-inch in diameter. Full-port bore size equals pipe size; standard-port bore size is the next smaller pipe size. Full port valve bodies require high torque to open and close the ball. The Belimo Characterized Control Valve offerings, CCV and HTCCV, are standard port valves. The full-port ball valve provides minimal resistance to flow and thus creates only a very small pressure drop when it is full open; it is typically used for isolating flow. The standard-port ball valve causes a larger pressure drop when it is full open; it is typically used for regulating flow to a coil.

A modulating actuator will position, or throttle, the damper or valve as commanded by the controller to achieve a desired position or flow.  An open/close, or on/off, control signal produces a two-position response (0% open or 100% open) for the damper or valve; usually with 24 VAC to 230 VAC contacts.

Valves are typically sized based on the required flow to a given distribution point. Cv is the capacity of the valve to deliver flow with an available differential pressure (∆P) across the valve. Cv by definition is the number of gallons per minute (GPM) a valve will flow with a  1 psi pressure drop across the valve. For example a valve with a Cv of 10 will flow 10 GPM with a 1 psi pressure drop. The formula used to select the valve Cv with the specified differential pressure is: Cv=GPM/((SQ RT(∆P)). If the specified ∆P is 4 psid and full flow is 10 GPM the calculated CV is 10/SQ RT of 4 = 5.

Parameters for valve selection are as follows:

• Full flow GPM (or steam lbs/hr capacity)
• With pressure independent (PI) valves, only the full flow GPM is required to select the body size for series: ePIV, PIQCV, or Energy Valve
• Design pressure drop to achieve full flow (N/A for PI Valves between 5-50 psid)
• Valve porting, 2-Way or 3-Way (if 3-way is it mixing or diverting)
• Valve type: CCV, Globe, PI, Butterfly, Rotary, ZoneTight
• Control Signal: On/Off, Floating, Proportional, or other
• If On/Off, what is the voltage (24V,110V, 230V or other)
• If Proportional what is the control signal input (2-10VDC, 0-10VDC, or other)
• Fail-safe on power loss, if yes specify the fail position
• Any other items: end switches, feedback, conduit connections, etc.
• Outdoor weather covers, or NEMA 4 enclosure
• Media type and application temperature

Another consideration when selecting a valve is never reduce the valve smaller than half the line size.  When a smaller valve than the pipe size is installed, pipe reducers have to be used. The resultant Cv value of the valve with the reduction fittings will be less than the nominal Cv value. Fp (friction from piping) is the piping geometry correction factor. Cvc = Fp x Cv states that the corrected Cv equals the geometry factor times the Cv. Fp = 1 when the valve is the same as the pipe size. 

The pipe geometry has a strong effect upon valves which have a large Cv-value compared to their size, such as full ported ball valves and butterfly valves. Most globe valves and reduced port ball valves are affected relatively little.  The pipe geometry has its largest influence when the valve is fully open, but it is insignificant when the valve is almost closed.  Therefore, the pipe geometry has a distorting effect upon the valve characteristics. Also when reducing, use pipe and/or valve supports since reducers weaken the structural strength of the assembly. 

When installing actuated valves, it is important to consider position orientation. Actuator can be mounted in any orientation when mounted onto a damper. When an actuator is mounted on a valve the actuator should not be mounted below horizontal on most valves in order to avoid water damage to the actuator that may occur if there is condensation or a water leak that travels along the piping and into the actuator. When an actuator is mounted on a globe valve, the actuator cannot be mounted lower than 45 degrees of center unless additional bracing is provided.

As always, we at G&D Chillers are here to answer any questions that you may have. Feel free to reach out and we will be happy to help.