Intelligent digital electric contact pressure gauge
1、 Product Overview:
The intelligent digital electric contact pressure gauge is an online measuring instrument controlled by a microcontroller. It is an intelligent pressure detector that integrates pressure measurement, upper and lower limit alarm, 4-20mA output, 485 communication, and LCD display; It has the functions of on-site direct display, convenient use, and remote monitoring. The front-end adopts a high-precision piezoresistive pressure sensor, and the output signal is amplified and processed by a high-precision, low-temperature drift amplifier. It is then sent to a high-precision A/D converter and converted into a digital signal that can be processed by a microprocessor. After calculation and processing, the actual pressure value is displayed on an LCD monitor. Setting upper and lower limit alarm values, automatically controlling the action of pumps, valves, or alarms to achieve timely and effective production control. Especially when used in places with corrosion, vibration, etc., its extraordinary performance is even more evident. This product has been certified by national metrology and explosion-proof departments and has been widely used in the fields of tap water, water treatment, petroleum, chemical, power, and metallurgy.

2、 Product features:
1. Large screen: Large screen LCD display, with intuitive and clear readings.
2. High precision: Advanced microprocessor technology, imported measurement and control chips, stable performance, high precision, and wide adaptability to environmental temperatures.
3. Low power consumption: Ultra low power intelligent control.
4. Multi functional: pressure measurement, upper and lower limit alarm, 4-20mA output, 485 communication, LCD display, range migration, etc.
5. Vibration resistance: The device undergoes anti vibration treatment, is securely assembled, and can be used normally in vibration environments.

3、 Technical parameters:
1. Measurement range: Gauge pressure:- 100KPa ~60MPa
2. Accuracy level: 0.2 level
3. Display mode: 4-digit dynamic display
4. Large load of electrical contacts: 5A (AC250V)
5. Overload pressure: twice the standard range
6. Medium temperature:- 20℃～70℃
7. Operating temperature:- 20℃～60℃
8. Explosion proof level: ExiaIIBT4
9. Process connection: M20 × 1.5 (external thread) or according to user requirements

4、 System connection diagram:

5、 Measurement Usage Instructions
When using, first fix the instrument on the pipeline or pressure vessel. To ensure measurement accuracy, the instrument can also measure gases or liquids below 85 ℃. If the temperature exceeds 85 ℃, a radiator should be added, otherwise the measurement accuracy cannot be guaranteed. The liquid receiving part of the instrument is made of stainless steel metal material and diffusion silicon sensor. Diaphragm type digital electric contact pressure gauge should be selected for measuring strong acid and strong alkali media.

6、 Wiring method

Figure 1: Wiring Diagram
Wiring instructions: Two contacts use a common point. When the high limit setting value is reached, the high limit contact is conductive to the common point of the contacts. When the low limit contact is reached, the low limit contact is conductive to the common point of the contacts.
The negative end of the power supply is a suspended wire connector. Engineers can connect the negative end of the power supply to the wire connector and seal it with insulating tape.

Figure 2: Schematic diagram of panel buttons
7、 Contact threshold setting
This instrument has two electrical contacts (one normally closed and one normally open). Before using it correctly, the action pressure value should be set. The default two action pressure values at the factory are both full range. On the lower part of the front panel of the instrument, three operation buttons can be seen (see Figure 2). The button on the left is responsible for entering the pressure value setting mode. Press the setting entry button (release it after 1 second to enter the low limit contact (which is a normally closed contact) L, the pressure value setting program. At this time, the LCD screen displays the last set value. Then press the △ key to increase the value, press the ▽ key to decrease the value. When you reach the desired pressure value, press the confirm key for more than 1.5 seconds and release it. At this time, the low limit contact pressure value is stored. Immediately enter the high limit contact (which is a normally open contact) H pressure value setting program, using the same method as the previous electrical contact setting method, and then press the confirm button for 1.5 seconds to complete the setting completely.

8、 Instructions for using electrical contacts
This instrument has two electrical contacts (customizable opening and closing types). When the pressure exceeds the set action pressure value, the corresponding electrical contacts close and can withstand 5A, 250V AC voltage.

9、 External dimensions

10、 Fault diagnosis:
This product has the functions of sensor failure diagnosis and over range protection. When the pressure sensor is not reliably connected to the circuit, the instrument can automatically diagnose this state and display the word "Err" on the LCD screen. This state will be maintained until the sensor resumes reliable operation.
When the measured pressure range exceeds 10% of the instrument's measurement range, it is considered an over range state. For the safety of the instrument, it is recommended to promptly resolve this situation. In this case, the LCD screen will still display the pressure value normally, but the accuracy will be reduced.
To prevent damage to the instrument, please use an instrument with a measurement range greater than about 20% of the frequently used high pressure value.