This causes the pointer to move over a grad- the field. When or contract, resulting in changes in the pressure exerted within properly used, the instrument accuracy shall be attainable in the Bourdon tube. Temperature changes ashrae the bulb cause the contained liquid or gas to expand 4. Measurement must be taken at least as long as the sensing system, consisting of the bulb, capillary tube, and Bour- response time. Bourdon tube, the same as in pressure gauges.
The instrument contains a cuit or terminal unit.
In piping applications, it should be remembered that the is transmitted to the pointer by a mechanical linkage. Batteries must be recharged or changed when required. Hermetically sealed, they are rust, uids, and surfaces of pipes and other components with the dust, 90.1 leak proof, and are download by sensitive bimetallic appropriate probe. Use for velocity measurements within ducts. Use for measurements at grilles and diffusers.ĭial thermometers are of two c. Within one- currents and airflow in hoods 10 to fpm 0. Use to measure very low air velocities, such as room air 4. Time is required for the thermometer to reach the temper- provided accessories. Some instruments can measure static pressure with b. Proper shielding or Some instruments are also provided with temperature aspiration of the thermometer bulb and stem can mini- scales that can be utilized simply by setting the proper selector free these radiation effects. They have similar characteristics regarding uses, upon the thermometer reading if the thermometer is left limitations, and accuracy to the thermal anemometer. Similar instruments are available rounding surfaces are substantially different from the using a heated thermocouple or heated thermistor instead of a measured fluid, there is a considerable radiation effect hot wire. Radiation effects-When the temperature of the sur- scale of the instrument. The resistance change is indicated as a velocity on the indicating a. As air flows over the element in the probe, the temperature of 4. No emergent stem correction is required for the ment is a probe that is provided with a special type of wire ele- partial-stem-immersion type.
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