lcd display manufacturers in china

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1 Temperature Meter

The chemical reactions and changes in petrochemical production need to be carried out smoothly under specific temperature and pressure environments. In order to monitor the temperature changes in real-time and control the temperature range precisely, a certain number of temperature meters must be set in the production.At present, the production temperature is mainly measured by contact, and the temperature data is measured by thermocouple, thermal resistance and other temperature measuring components, and the automatic temperature control effect is achieved with the help of Fieldbus technology.

Identification of thermocouple and thermal resistance

The appearance of industrial thermocouple and thermal resistance protection bushing is almost the same, and some temperature measuring elements are very small, such as armored type, and the appearance of both is basically the same.

A.In the case of the nameplate, knowing the model can be identified through the nameplate.

Thermocouple: the principle is the thermoelectric effect, and its grading number is S, B, E, K, R, J, T, seven kinds of standardized models.

Thermal resistance: the principle is the thermal effect of resistance (the resistance value of a conductor or semiconductor changes with the temperature of this property), and its grading signs are Pt10, Pt100, Pt1000, Cu50, and Cu100. PT100 and CU50 are the most widely used.

B.In the case of no nameplate, and do not know the model, the following methods can be used to identify.

(1) look at the lead line of the temperature measuring element, usually, there are only two leads of the thermocouple, if there are three leads is the thermal resistance.

However, for those with four lead lines, it is necessary to measure the resistance value to determine whether it is a two-branch thermocouple or a four-wire thermal resistance.First, find two pairs of leads with almost zero resistance from the four leads, and then measure the resistance value between the two leads. If it is infinite, it is a double thermocouple. A pair of leads with almost zero resistance is a thermocouple.If the resistance of the two pairs of lead wires is between 10-110, it is a single four-wire thermal resistance, and its resistance value is closest to the thermal resistance of what index number, it is the thermal resistance of the index number.

(2) if there are only two leads, you can use the digital multimeter to measure the resistance value to judge, because the resistance value of the thermocouple is very small, the thermal resistance is almost zero;If the resistance value is very small, it may be a thermocouple.Thermal resistance at room temperature, its minimum resistance value will be greater than 10.

2 Pressure Meter

Pressure gauges are of various types, such as pressure sensors, pressure transmitters, special pressure gauges, etc. Pressure gauges can be used for pressure measurement in extreme environments such as high temperature and corrosion, and can also be used for pressure measurement in easy-to-crystallize and powder-granular media.

Under normal circumstances, the pressure regulation system will transmit the collected signal to the distributed control system with the help of the pressure transmitter to realize the automatic pressure measurement and control effect.

3 Level Instrument

According to the different measuring methods, the level instrument can be divided into buoyancy type, direct reading type, differential pressure type, radiation type, radar type, etc. In petrochemical production, radar level instrument is gradually favored by the industry because of its high measuring accuracy and strong applicability to petrochemical materials.

4 Flowmeter

Flowmeter is basically based on two measuring principles, one is volume flow measurement, the other is mass flow measurement.Orifice differential pressure flowmeter, electromagnetic flowmeter, ultrasonic flowmeter, vortex street flowmeter, etc., almost all flowmeters are volume detection flowmeters now.Because now is the use of intelligence, as long as the selection of flow meter internal parameters change, can also detect the mass flow rate.