The selection and installation of the temperature instrument

Temperature instrument choice: in meet the measuring range, working pressure and accuracy requirements, should be preferable. Pressure type thermometer: - Under 80 ℃ low temperature, can't close observation, a vibration and accuracy requirement is not high situation can choose. Glass thermometer: because mercury pollution, is generally not recommended. Except as a complete set of machinery, measurement accuracy is not high under the condition of use. Temperature protection tube choice: (1) detecting element insertion length choice: the insertion length should be selected to detect components sensitive to temperature changes measured medium, and the position of representative for the principle. (2) temperature protection pipe material qualitative choice: should be selected according to the conditions of the measured medium right. Temperature instrument installation: (1) components installed on the pipeline, should guarantee the temperature measuring elements and fluid full contact, therefore, demand falling in to test components to meet flow measured medium, and the flow of measured medium into at least 90 o, never measured medium and form downstream; (2) install mercury thermometer or thermocouple, if the nominal pipe diameter is less than 50 mm, and installing resistance thermometer or bimetallic thermometer nominal pipe diameter less than 80 mm, the thermometer should be installed in the expansion of arm; (3) the work side of temperature measuring element in pipe flow rate, biggest expansion thermometer should be the center of the temperature measuring points in pipe line, thermocouple, platinum thermal resistance, copper thermal resistance to protect casing should be across the beam center line at the end of 5 ~ 10 mm, 50 and 25 ~ 30 mm to 70 mm. The center of the pressure type thermometer bulb deficiency with the center line of the pipeline; (4) to have enough insertion depth, falling in to to reduce the measurement error; (5) thermocouple and thermal resistance of the junction box should be down, to escape the rain water or other liquid infiltration affect measurement, thermocouple shall not have a strong magnetic field; 6 to reduce temperature lag, but outside the protection and protection of casing pipe with good heat transfer between fillers, such as transformer oil ( < 150℃) Or copper chip, quartz sand, > 150℃) 。 Temperature meter on pipeline equipment installation: (1) threaded head fixed; Threaded head fixed way, no corrosive medium is generally applicable to pipe installed on the temperature measuring element. Has the advantages of small size, installation is relatively compact. (2) the flange fixed. Flange fixed way, suitable for temperature measuring element installed on the equipment. In high temperature and strong corrosive medium, the coking in slurry medium, virulent, powder medium and catalyst layer of multi-point temperature measurement, also should use the flange fixed way, with convenient maintenance.