Pressure gauges and temperature gauges are both commonly used industrial instruments for measuring the pressure and temperature of fluid media. The pressure gauge measures and indicates pressure higher than the instrument’s ambient pressure using the elastic element as the sensitive component. The application is extremely common. It is in almost all of the industrial processes and scientific research areas. In the heat pipe network, oil and gas transmission, water supply and gas supply system, vehicle maintenance workshop and other fields can be found everywhere. Especially in the industrial process control and technical measurement process, due to the mechanical pressure gauge of the elastic sensitive element having a high mechanical strength as well as production convenience and other characteristics, the mechanical pressure gauge has been more and more widely used.
Temperature gauge is a use of different principles to measure the object (or space) temperature or temperature gradient of the apparatus. Commonly, there are pointer bimetal temperature gauges with the dial, which can directly measure gas, liquid, and steam. Widely used in machinery, shipbuilding, petrochemical, metallurgy, electric power, light industry, research, and other sectors.
- Measurement Object
The main difference between the pressure gauge and the temperature gauge is that the measurement object is different. The pressure gauge is mainly used to measure fluid or gas pressure in the pipeline or container. In the industrial production process, often need to measure the pressure of the fluid or gas, to ensure the normal operation of the process and production safety. Pressure gauge measurement is a commonly used measurement method to accurately measure the value of various pressures. Common pressure gauge measurement objects include pressure in hydraulic systems, atmospheric and liquid pressure in pneumatic systems, tire pressure in automobile tires, air pressure in cylinders, and pressure in industrial pipelines. Different measurement objects need to be measured using different pressure gauges. The temperature gauge is mainly used to measure the fluid medium, but also can measure the temperature of various solid surfaces, gases, liquids, rubber, asphalt, plastics, and so on.
- Measurement Principle
The pressure gauge and temperature gauge measurement principle is also different. The pressure gauge is based on the principle of elastic deformation of the spring for measurement, when the pressure increases, the spring elastic deformation occurs, through the agency will be deformed into the pointer rotation angle, so as to achieve the purpose of measuring the pressure value. The temperature gauge is to use the thermal expansion characteristics of the medium to measure the temperature, when the temperature of the heated medium changes, through the thermistor, thermocouple or infrared temperature measurement, etc., the thermal expansion of the corresponding electrical or optical signal is converted to a temperature value.
- The Scope of Use
The pressure gauge is commonly utilized to gauge the pressure in a given medium, and is extensively employed within the pharmaceutical, chemical, petroleum, aviation, and other industrial sectors. The temperature gauge is commonly used in measuring mechanical equipment, heating equipment, air conditioning and refrigeration, food processing, and other industries, but also widely used in rubber, textile, paper, shipbuilding, food, steel, and non-ferrous metals, petroleum products, ceramics, glass, and other industries, the object of the application is more extensive.
- Structure Form
The pressure gauge is usually in the form of a dial to show the pressure value, through the mechanical transmission will be converted to the pressure value of the movement of the pointer. The temperature gauge is usually in the form of a pointer to show the temperature value, including a glass thermometer, metal thermometer, electronic thermometer, and so on.
- Installation Location
Temperature gauge and pressure gauge installation locations are based on the specific workplace and equipment to decide. Generally speaking, the temperature gauge should be installed on or near the surface of the object to be measured in order to accurately measure its surface temperature. If the temperature of a fluid is being measured, it should be installed at the inlet or outlet of the fluid. Moreover, temperature gauges are usually mounted on the side or bottom of a pipe or vessel to allow direct reading of the temperature value of the medium. Whereas the installation location of the pressure gauge should take into account the type of pressure to be measured, if it is liquid pressure, it should be installed at the inlet or outlet of the liquid, and if it is gas pressure, it should be installed in the middle of the gas pipeline or close to the source of the gas. It is also common for pressure gauges to be mounted on the side or top of a pipe or vessel where the pressure value of the medium can be read directly.
Furthermore, it is essential to ensure the installation of temperature and pressure gauges prioritizes safety and reliable functioning to prevent any mishaps or errors during usage. Therefore, when choosing the installation location, you need to make a reasonable installation according to the specific working environment and equipment requirements.
- Installation Method
The connection method of pressure gauge is usually flange connection, threaded connection, or insertion connection, which needs to be connected with a pipeline or container. The threaded connector and the installation of pressure gauges are divided into the direct installation of pressure gauges, embedded (disk-mounted) pressure gauges, and convex-mounted (wall-mounted) pressure gauges.
Temperature instrumentation installation can be divided into four types according to the fixed form: flange fixed installation; threaded connection fixed installation; flange and threaded connection common fixed installation; and simple protective sleeve insertion installation. One of the most commonly used forms of installation is flange fixed installation and threaded connection fixed installation. Installed in the equipment or high temperature, corrosive media pipeline, temperature instrumentation should be selected flange connection. The threaded connection is suitable for non-corrosive media, and the pressure level is not a high pipeline, temperature instrumentation should be installed in the measurement of the best position. When equipped with an additional protective sleeve, flange and threaded connection commonly fixed can be selected. It applies to corrosive media pipelines and equipment installation. Simple protective sleeve insertion installation refers to a fixed sleeve and ferrule type interchangeable sleeve (insertion depth adjustable) two forms, applicable to the bar thermometer in the low-pressure pipeline for temporary testing of the installation.
To summarize, this paper compares the differences between pressure gauges and temperature gauges from various aspects, such as measurement object, measurement principle, and scope of use. In practical applications, it is crucial to choose the right meter for measurement according to different application scenarios and needs.