First, the principle

Let's clarify the principle of the lower pressure transmitter and differential pressure transmitter.

1, Principle of pressure transmitter

The electrical components that Pressure Transmitters use to sense pressure are generally resistance strain gages. Resistance strain gages are sensitive devices that convert the pressure on the device under test into an electrical signal. The most commonly used resistance strain gages are metal resistance strain gages and semiconductor strain gages. There are two types of metal resistance strain gauges: wire strain gauges and metal foil strain gauges. Usually, the strain gauge is tightly adhered to the substrate that generates mechanical strain through a special adhesive. When the substrate undergoes a stress change, the resistance strain gauge also deforms together, causing the resistance value of the strain gauge to change, thereby increasing The voltage across the resistor changes.

2, Principle of differential pressure transmitter

The result measured by the differential pressure transmitter is the pressure difference, that is, △ P = ρg △ h. And because the oil tank is often cylindrical, the area S of the cross-section circle is constant, then, gravity G = △ P · S = ρg △ h · S, S is not changed, and G is inversely proportional to △ P. That is, as long as the △ P value is accurately detected, it is inversely proportional to the liquid level height h and proportional to the height difference Δh. When the temperature changes, although the oil volume expands or contracts, the actual liquid level increases or decreases. The pressure is always the same.

Features

Characteristics of pressure transmitter

1. The Pressure Transmitter has the characteristics of reliable operation and stable performance;

2, dedicated V / I integrated circuit, fewer peripheral devices, high reliability, simple and easy maintenance, small size, light weight, extremely convenient installation and commissioning;

3. Aluminum alloy die-casting shell, three-end isolation, electrostatic plastic spray protection layer, durable;

4, 4-20mA DC two-wire signal transmission, strong anti-interference ability, long transmission distance;

5, LED, LCD, pointer three indicators, the field reading is very convenient. Can be used to measure viscous, crystalline and corrosive media;

6.High accuracy and high stability. In addition to the imported original sensor, which has been corrected by laser, fine compensation for the comprehensive temperature drift and nonlinearity of the whole machine in the operating temperature range is performed.

Differential Pressure Transmitter features

1, measurement characteristics, for pressure, differential pressure, liquid level, flow measurement

2, digital accuracy: + (-) 0.05%

3. Simulation accuracy: + (-) 0.75% + (-) 0.1% F.S

4. Full performance: + (-) 0.25F.S

5. Stability: 0.25% for 60 months

6. Range ratio: 100: 1

7.Measurement rate: 0.2S

8. Miniaturized (2.4kg) all stainless steel flange, easy to install

9. Process connection is compatible with other products for optimal measurement

10. Intelligent transmitter using 16-bit computer

11. Standard 4-20mA DC, with digital signal based on HART protocol, remote control

12.Support the upgrade to fieldbus and field control technology

三 、 Division

It is obvious from the principle and characteristics that there is a distinction between them. The pressure transmitter measures the pressure in the pipeline, and the differential pressure transmitter is used to measure the differential pressure with the orifice flowmeter. Therefore, we must look at the transmitter in two. We cannot simply say that the transmitter is universal and can measure all the pressure and differential pressure.