Sanitary ball valve temperature measurement:
Based on operating conditions, temperature measurement can be conducted using glass tube liquid thermometers, bimetallic thermometers, resistance thermometers, or thermocouples. With the exception of the glass tube liquid thermometer, which must be inserted into a sleeve, all of the aforementioned thermometers can be directly inserted into pipes or placed into sleeves. When the temperature is below 150°, it is advisable to insert the temperature measuring device directly into the pipe without an additional sleeve.
2. When conducting any temperature measurements, the following precautions should be taken:
(1) The temperature measuring device should not have significant heat transfer due to radiation or conduction with the external environment, excluding the medium being tested.
The adjacent area of the insertion point and the exposed part of the temperature measuring device should be insulated.
(3) For small-diameter pipelines, the temperature-measuring device should pass through the centerline of the pipe; when the pipeline diameter exceeds 300mm, it should be inserted at least 150mm into the medium flow.
(4) On pipelines conveying compressible fluids, temperature sensors should be installed where the fluid velocity does not exceed 30 m/s during any flow measurement, whenever possible. If such installation is not feasible, temperature readings may need to be corrected to the appropriate static or total temperature.
(5) The insertion position of the temperature measuring device should be such that the measured temperature accurately represents the temperature of the flowing medium as described in the test setup.
When using a glass tube mercury thermometer to measure temperature, the thermometer should have a graduated rod. If the difference between the measured temperature and the ambient temperature is greater than 5° and the mercury is exposed, a rod extension correction should be applied, or an exposed rod thermometer should be used.
When using a thermometer sleeve, the sleeve should be thin-walled with a diameter as small as possible. The exterior of the sleeve should be free from corrosion or debris, and it should be filled with an appropriate fluid, but not mercury. Mercury has a very low evaporation pressure, which can pose serious health hazards to personnel. Of course, if mercury is used for this purpose, appropriate precautions must be taken.
5. If a thermocouple is used, it should have a焊接 hot junction and must be calibrated along with its connecting wires within the anticipated operating range. The thermocouple should be constructed from materials suitable for the measured temperature and medium. Its electromotive force should be measured using a potentiometer or millivoltmeter. The cold junction of the thermocouple should be achieved using an ice bath (refer to the standard instrument) or by adding a compensation circuit to the potentiometer.
