Infrared Thermometers infer the temperature of an object by measuring the infrared thermal radiation emitted from the object. Objects at thermal equilibrium must balance the energy that is entering the object with the energy that is leaving the object. Often, the energy leaving the object is emitted as electromagnetic radiation. Continue reading “Infrared Thermometers”
Calibrating measurement instrumentation is something that should never go overlooked. To calibrate instrumentation means to determine, check, or rectify the graduation of any instrument giving quantitative measurement. Calibrating a device ensures that the instrument will properly measure within the desired range for your application. This is important because a properly calibrated measurement device will help the user to maintain his or her system. A device can be calibrated either at the factory where the device was manufactured or within the field. Calibration certificates may be obtained once a device has been calibrated. Continue reading “The Importance of Calibrating Measurement Instrumentation”
Dwyer Instruments, Inc. offers a multitude of sensors for monitoring air velocity in HVAC systems. Some of this instrumentation has a simple construction (Pitot tubes, for example) while others are more complex, such as hot-wire anemometers.
The initial term and first “hot-wire anemometer” was developed back in 1914 by Louie Vesso King. He is also accredited for King’s Law, which mathematically describes heat transfer in air flows using a heated wire. As the air moves over the wire, it causes a loss of temperature in the wire and removes some of the wire’s heat energy. Continue reading “Understanding Air Velocity Sensors”
Thermistors are based on the principal that the electrical resistance of semiconductor materials is a function of the temperature. Thermistors work well over smaller temperature ranges with better accuracy than (RTD) but are very non-linear. They also generally offer better response times. Thermistors have much higher resistance values than RTDs, with ranges typically ranging from 100 ohms to 100 megaohms.