For Belimo combination fire/smoke damper actuators intended for installation in accordance with National Protection Association Standard for Installation of Air Conditioning and Ventilating Systems, NFPA 90A, damper actuators must meet the construction and performance requirements in UL555: Standard for Fire Dampers and UL555S: Standard for Smoke Dampers. Often, customers replace damper actuators for varying reasons […]
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Application Tips: Determining Air Flow in Cubic Ft./ Min
To calculate Air Flow in Cubic Feet per Minute (CFM), determine the Flow Velocity in feet per minute, then multiply this figure by the Duct Cross Sectional Area. Air Flow in CFM (Q) = Flow Velocity in Feet Per Minute (V) x Duct Cross Sectional Area (A)
Read PostSelecting the Appropriate Pressure Transmitter
With so many choices, selecting a pressure transmitter can be a frustrating endeavor, but it doesn’t have to be. With a few simple steps, finding the right transmitter for your application can be considerably easier.
Read PostTech Talk: I need an explosion-proof control panel with a few pilot lights and…
Q: I’ve been buying explosion-proof enclosures and devices from Kele, and I must say that the Hazardous Locations section of your catalog is a gold mine of hard-to-find products! Now I need an explosion-proof control panel with a few pilot lights and externally operable selector switches mounted on the door of the panel. Can Kele help me with […]
Read PostTech Talk: Timing relays are confusing to me. Can you explain the difference between single-shot and interval timers? What happens if the output driving the relay changes state during a timing sequence?
When all of the possible combinations of timing states and initiating device transitions are considered, a stronger word than “confusing” may be in order! Below are some timing diagrams and sequences of operation in simple terms that may be of help. Since it is an electronic circuit that is energized rather than a coil, the […]
Read PostTech Talk: Air Capacity and Consumption – Choosing Electronic to Pneumatic Transducer
When it comes to selecting an electronic to pneumatic (E/P) transducer, the type of input and the pressure range of the output are the most common selection criteria considered. There are a couple of other specifications that are worth reviewing to select the best transducer for the job. These additional specifications are Air Consumption and […]
Read PostEasily Configure Valve Sizes Fast!
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 […]
Read PostRelay Fundamentals
Open an HVAC control panel, and you’re likely to find at least one relay mounted inside. Sometimes you find lots of relays! Even though relay technology has been around since the 1800s, there is still a need for relays in control panels. What components make up a relay? How are relays typically shown in wiring […]
Read PostDivide & conquer those hard-to-read flow meter pulses
“Currently” Playing: Connecting A 4-20 mA Constant-Current Signal To Multiple Loads
One of the most popular and long-lived methods for transmitting analog control signals in the HVAC and industrial control worlds is the “constant-current signal loop.” In this scheme, the value of the current flowing in the circuit is the control variable, rather than any voltages that may appear at different points in the circuit. The […]
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