Advantages and disadvantages of pressure thermometers
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A pressure-type thermometer uses the volume expansion or pressure change that occurs in a liquid, gas, or saturated vapor within a closed container when heated as the signal for measurement. Its basic structure consists of three parts: a temperature bulb, a capillary tube, and an indicator gauge. It is one of the earliest methods applied to temperature control in production processes. The pressure-type temperature measurement system remains a widely used measurement method for local indication and control of temperature. The advantages of pressure-type thermometers are: simple structure, high mechanical strength, and resistance to vibration. It has a low price and does not require external energy. The disadvantages are: the temperature measurement range is limited, generally ranging from -80 to 400°C; there is significant heat loss and a slow response time; the instrument’s sealing system (thermocouple bulb, capillary tube, bimetallic strip) is prone to damage and difficult to repair, requiring replacement; the measurement accuracy is greatly affected by the ambient temperature and the installation position of the thermocouple bulb, resulting in relatively low precision; the capillary tube has a limited transmission distance
This post was last edited by qugd on 2011-12-19 14:40. Such products are now rare in modern industry. Some friends, even when you meet them, you don’t know what they are like. Take a look at what these things look like. http://fs01.bokee.net/userfilespace/2009/12/26/lyyxsh2451989.jpg http://ftp.gongkong.com/UploadPic/temp/2008-11/2008112613094900001.jpg Thermosets can not only be used for temperature measurement, but also serve as control elements that can be connected directly to actuators. Because the force of thermal expansion and contraction is very strong.
Original poster, among mechanical temperature measuring instruments, compared to bimetallic thermometers, these types of thermometers are not cheap, but they offer a wide temperature measurement range – from -200 to 800 degrees.