Capacitive Differential Pressure Transmitter

I. Product Overview:

ZW1151DP series capacitive differential pressure transmitter is a new type of instrument developed jointly according to international advanced technology and domestic technical forces. The instrument adopts micro-processing technology to compensate the temperature characteristics and non-linearity, which greatly improves the measuring accuracy, temperature characteristics, expands the range ratio, adds intelligent functions, and further meets the requirements of high reliability and high stability of the instrument in the industrial field. The application of digital technology in capacitive pressure/differential pressure transmitter can not only ensure the high reliability and other superior performance of the instrument, but also realize the remote digital connection between intelligent instrument and control room, and ensure the fast and reliable communication. The control room can query the transmitter remotely or configure it in real time.

II. Working Principle:

The process pressure of ZW 151DP series capacitive differential pressure transmitter is transmitted to the center measurement diaphragm of the delta chamber through the isolation diaphragm on both sides or one side and the filling liquid. The central diaphragm is a tensioned elastic element, which produces a corresponding deformation displacement for the pressure difference between the two sides acting on it. Its displacement is proportional to the differential pressure. The Zui large displacement is about 0.1mm. This displacement transformation forms a differential capacitance on the capacitor plate. The differential capacitance is converted into a 2-wire 4-20mADC signal output by an electronic circuit.

3. Application occasions:

ZW 151DP series capacitive differential pressure transmitter is mainly used to measure the pressure and differential pressure of gas, liquid and steam, and then convert it into 4-20mA.DC signal output. It can measure absolute pressure and differential pressure of exhaust system, distillation tower, evaporator and crystallizer. Widely used in petroleum, chemical, power, paper, food and municipal industries, a full range of differential pressure, pressure, absolute pressure measurement.

Fourth, main characteristics:

1. Super measurement performance for pressure, differential pressure, liquid level and flow measurement;

2. Digital accuracy: +(-) 0.05%;

3. Stability: 0.25% for 60 months;

4. Range ratio: 100:1;

5. Measurement rate: 0.2S;

6. Miniaturized (2.4kg) stainless steel flange, easy to install;

7. Process connection is compatible with other products to realize measurement.

8. The sensor (technology) with H-alloy sheath has achieved excellent cold and thermal stability.

9. Using 16-bit computer;

10. Standard 4-20mA, with HART-based digital signal, remote control supports upgrading to fieldbus and field control technology.

Technical parameters:

1. The object of use: liquid, gas and steam;

2. Output signal: 4-20 mADC (special for four-wire 220 VAC power supply, 0-l0 mADC output);

3. Power supply: 12-45 VDC, generally 24 VDC;

4. Load characteristics: It is related to power supply. The load capacity at a certain power supply voltage is shown in the figure above (load characteristics). The relationship between load impedance RL and power supply voltage VS is: RL < 50 (Vs-12).

5. Indicator table: pointer linear indicator 0-99% equal scale or LCD liquid crystal, LED digital tube display;

6. Explosion-proof: a. Flameproof dIIBT4;

B. Intrinsically safe iaIICT6;

7. Range and Zero: External continuous adjustable;

8. Positive and negative migration: After positive or negative migration of zeros, the upper and lower limits of measurement range and measurement range can not exceed 99% of the upper limit of measurement range.

9. Temperature range: Amplifier operating temperature range: - 29 ~93 ~C;

10. Static pressure: 1, 4, 10, 25, 32 MPa;

11. Humidity: Relative humidity is 0-99%.

12. Volume uptake: <0.16cm3;

13. Damping (step response): When silicone oil is filled, it can be continuously adjusted from 0.2S to 1.67s.

6. Daily use precautions:

1. Do not use voltage higher than 36V to add to the transmitter, causing damage to the transmitter;

2. Do not touch the diaphragm with hard objects, resulting in damage to the isolation diaphragm.

3. Ice is not allowed in the measured medium. Otherwise, the isolation diaphragm of the damaged sensor elements will lead to the damage of the transmitter. If necessary, temperature protection should be carried out to prevent the transmitter from freezing.

4. When measuring steam or other high-temperature medium, its temperature should not exceed the limit temperature of the transmitter, and the radiator must be used when it is higher than the limit temperature of the transmitter.

5. When measuring steam or other high temperature medium, heat sink should be used to connect the transmitter with the pipeline, and the pressure on the pipeline should be used to transmit to the transformer. When the measured medium is water vapor, appropriate amount of water should be injected into the radiator tube to prevent the superheated steam from directly contacting the transmitter and damaging the sensor.

6. In the process of pressure transmission, the following points should be paid attention to.

A. Do not leak air at the junction of transmitter and radiator pipe.

B. Before starting to use, if the valve is closed, the valve should be opened very carefully and slowly, so as not to directly impact the sensor diaphragm and damage the sensor diaphragm.

C. The pipeline must be unblocked. The sediment in the pipeline will pop up and damage the sensor diaphragm.

All, in the use of smart pressure transmitter must bear in mind the above points, in order to avoid unnecessary losses.