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Frequently Asked Questions of Firstrate Pressure Sensor

(Summary description)1. After pressurizing, the output of the transmitter does not change? Answer: In this case, first check whether the pressure port is leaking or blocked. If it is not confirmed, check the wiring method. If the wiring is correct, check the power supply. If the power supply is normal, check whether the sensor zero has output, or perform a simple addition. Look at whether the output changes. If there is a change, the sensor is not damaged. If there is no change, the sensor has been damaged. Other reasons for this situation may also be damage to the instrument or other problems in the entire system.   2. The output of the pressure transmitter does not change, and the output of the pressure transmitter changes suddenly, and the zero position of the pressure relief transmitter cannot return? Answer: The reason for this phenomenon is most likely caused by the pressure sensor sealing ring. Generally, it is due to the specifications of the sealing ring (too soft or too thick). When the sensor is tightened, the sealing ring is compressed into the pressure port of the sensor to block the sensor. The pressure medium cannot enter when the pressure is high, but when the pressure is very high, the sealing ring is suddenly opened, and the pressure sensor is changed by the pressure. When the pressure drops again, the sealing ring returns to block the pressure port, and the remaining pressure cannot be released. Therefore, the zero position of the sensor cannot be lowered. The best way to eliminate this reason is to remove the sensor and directly check whether the zero position is normal. If it is normal, replace the sealing ring and try again.   3. The output signal of the transmitter is unstable?        Answer: There are several reasons for the unstable output signal:        A. The pressure source itself is an unstable pressure;        B. The anti-interference ability of the instrument or pressure sensor is not strong (check whether there are interference sources around, such as motors, inverters, etc.);        C. The sensor wiring is not firm (the cable wiring is bad or damaged, and the wiring needs to be re-wired);        D. Check the grounding condition of the equipment (the induced voltage will charge the sensor or the instrument casing);        E. Sensor failure;   4. There is no output when the transmitter is connected to electricity? Answer: The possible reasons are:        A. Wrong wiring (check both the instrument and the sensor);        B. Open circuit or short circuit of the wire itself;        C. The power supply has no output or the power supply does not match (check whether the input power supply meets the power supply range);        D. The meter is damaged or the meter does not match;        E. The sensor is damaged;   5. After the sensor is connected to the meter, there is no output display?    Answer: The sensor is connected to the instrument, and there is no output display. The sensor and the instrument can be tested separately to confirm which part of the fault is;           Disconnect the signal output line of the sensor and the instrument, first check whether the sensor output is normal;                 The current signal and voltage signal output can be detected separately according to the above figure. If the zero position is normal, slowly pressurize the sensor to see if the output value changes. If the output value changes, it means the sensor is normal and it can be judged as a failure of the instrument. (This method can also be used for sensors with mV signal output). The sensor can be powered by a separate external power supply or a meter to see if the sensor output is normal.   6. How does the installation position of the differential pressure transmitter affect the zero output? Answer: Due to the small measuring range of the differential pressure transmitter, the weight of the sensing element in the transmitter will affect the output of the differential pressure transmitter. Therefore, the zero position of the differential pressure transmitter will appear when the differential pressure transmitter is installed. Changes are normal. During installation, the pressure sensitive part of the transmitter should be made perpendicular to the direction of gravity. If the installation conditions are limited, the zero position of the transmitter should be adjusted to the standard value after installation and fixation.   7. Transmitter output ≥20mA? Answer: The possible reasons are:        A. Check whether the actual pressure exceeds the selected range of the pressure transmitter;        B. Caused by overload of the sensor (severe overload sometimes damages the isolation diaphragm);        C. Sensor failure;   8. The FST500-202 electronic pressure switch is not pressurized and the display is not zero? Answer: The possible reason is that the display of non-pressurization is not zero.        A. After the product is installed, there may be slight pressure on the equipmen

Frequently Asked Questions of Firstrate Pressure Sensor

(Summary description)1. After pressurizing, the output of the transmitter does not change?

Answer: In this case, first check whether the pressure port is leaking or blocked. If it is not confirmed, check the wiring method. If the wiring is correct, check the power supply. If the power supply is normal, check whether the sensor zero has output, or perform a simple addition. Look at whether the output changes. If there is a change, the sensor is not damaged. If there is no change, the sensor has been damaged.

Other reasons for this situation may also be damage to the instrument or other problems in the entire system.

 

2. The output of the pressure transmitter does not change, and the output of the pressure transmitter changes suddenly, and the zero position of the pressure relief transmitter cannot return?

Answer: The reason for this phenomenon is most likely caused by the pressure sensor sealing ring. Generally, it is due to the specifications of the sealing ring (too soft or too thick). When the sensor is tightened, the sealing ring is compressed into the pressure port of the sensor to block the sensor. The pressure medium cannot enter when the pressure is high, but when the pressure is very high, the sealing ring is suddenly opened, and the pressure sensor is changed by the pressure. When the pressure drops again, the sealing ring returns to block the pressure port, and the remaining pressure cannot be released. Therefore, the zero position of the sensor cannot be lowered. The best way to eliminate this reason is to remove the sensor and directly check whether the zero position is normal. If it is normal, replace the sealing ring and try again.

 

3. The output signal of the transmitter is unstable?       

Answer: There are several reasons for the unstable output signal:

       A. The pressure source itself is an unstable pressure;

       B. The anti-interference ability of the instrument or pressure sensor is not strong (check whether there are interference sources around, such as motors, inverters, etc.);

       C. The sensor wiring is not firm (the cable wiring is bad or damaged, and the wiring needs to be re-wired);

       D. Check the grounding condition of the equipment (the induced voltage will charge the sensor or the instrument casing);

       E. Sensor failure;

 

4. There is no output when the transmitter is connected to electricity?

Answer: The possible reasons are:

       A. Wrong wiring (check both the instrument and the sensor);

       B. Open circuit or short circuit of the wire itself;

       C. The power supply has no output or the power supply does not match (check whether the input power supply meets the power supply range);

       D. The meter is damaged or the meter does not match;

       E. The sensor is damaged;

 

5. After the sensor is connected to the meter, there is no output display?

   Answer: The sensor is connected to the instrument, and there is no output display. The sensor and the instrument can be tested separately to confirm which part of the fault is;

          Disconnect the signal output line of the sensor and the instrument, first check whether the sensor output is normal;

     

          The current signal and voltage signal output can be detected separately according to the above figure. If the zero position is normal, slowly pressurize the sensor to see if the output value changes. If the output value changes, it means the sensor is normal and it can be judged as a failure of the instrument. (This method can also be used for sensors with mV signal output). The sensor can be powered by a separate external power supply or a meter to see if the sensor output is normal.

 

6. How does the installation position of the differential pressure transmitter affect the zero output?

Answer: Due to the small measuring range of the differential pressure transmitter, the weight of the sensing element in the transmitter will affect the output of the differential pressure transmitter. Therefore, the zero position of the differential pressure transmitter will appear when the differential pressure transmitter is installed. Changes are normal. During installation, the pressure sensitive part of the transmitter should be made perpendicular to the direction of gravity. If the installation conditions are limited, the zero position of the transmitter should be adjusted to the standard value after installation and fixation.

 

7. Transmitter output ≥20mA?

Answer: The possible reasons are:

       A. Check whether the actual pressure exceeds the selected range of the pressure transmitter;

       B. Caused by overload of the sensor (severe overload sometimes damages the isolation diaphragm);

       C. Sensor failure;

 

8. The FST500-202 electronic pressure switch is not pressurized and the display is not zero?

Answer: The possible reason is that the display of non-pressurization is not zero.

       A. After the product is installed, there may be slight pressure on the equipmen

Information
1. After pressurizing, the output of the transmitter does not change?
Answer: In this case, first check whether the pressure port is leaking or blocked. If it is not confirmed, check the wiring method. If the wiring is correct, check the power supply. If the power supply is normal, check whether the sensor zero has output, or perform a simple addition. Look at whether the output changes. If there is a change, the sensor is not damaged. If there is no change, the sensor has been damaged.
Other reasons for this situation may also be damage to the instrument or other problems in the entire system.
 
2. The output of the pressure transmitter does not change, and the output of the pressure transmitter changes suddenly, and the zero position of the pressure relief transmitter cannot return?
Answer: The reason for this phenomenon is most likely caused by the pressure sensor sealing ring. Generally, it is due to the specifications of the sealing ring (too soft or too thick). When the sensor is tightened, the sealing ring is compressed into the pressure port of the sensor to block the sensor. The pressure medium cannot enter when the pressure is high, but when the pressure is very high, the sealing ring is suddenly opened, and the pressure sensor is changed by the pressure. When the pressure drops again, the sealing ring returns to block the pressure port, and the remaining pressure cannot be released. Therefore, the zero position of the sensor cannot be lowered. The best way to eliminate this reason is to remove the sensor and directly check whether the zero position is normal. If it is normal, replace the sealing ring and try again.
 
3. The output signal of the transmitter is unstable?       
Answer: There are several reasons for the unstable output signal:
       A. The pressure source itself is an unstable pressure;
       B. The anti-interference ability of the instrument or pressure sensor is not strong (check whether there are interference sources around, such as motors, inverters, etc.);
       C. The sensor wiring is not firm (the cable wiring is bad or damaged, and the wiring needs to be re-wired);
       D. Check the grounding condition of the equipment (the induced voltage will charge the sensor or the instrument casing);
       E. Sensor failure;
 
4. There is no output when the transmitter is connected to electricity?
Answer: The possible reasons are:
       A. Wrong wiring (check both the instrument and the sensor);
       B. Open circuit or short circuit of the wire itself;
       C. The power supply has no output or the power supply does not match (check whether the input power supply meets the power supply range);
       D. The meter is damaged or the meter does not match;
       E. The sensor is damaged;
 
5. After the sensor is connected to the meter, there is no output display?
   Answer: The sensor is connected to the instrument, and there is no output display. The sensor and the instrument can be tested separately to confirm which part of the fault is;
          Disconnect the signal output line of the sensor and the instrument, first check whether the sensor output is normal;
     
          The current signal and voltage signal output can be detected separately according to the above figure. If the zero position is normal, slowly pressurize the sensor to see if the output value changes. If the output value changes, it means the sensor is normal and it can be judged as a failure of the instrument. (This method can also be used for sensors with mV signal output). The sensor can be powered by a separate external power supply or a meter to see if the sensor output is normal.
 
6. How does the installation position of the differential pressure transmitter affect the zero output?
Answer: Due to the small measuring range of the differential pressure transmitter, the weight of the sensing element in the transmitter will affect the output of the differential pressure transmitter. Therefore, the zero position of the differential pressure transmitter will appear when the differential pressure transmitter is installed. Changes are normal. During installation, the pressure sensitive part of the transmitter should be made perpendicular to the direction of gravity. If the installation conditions are limited, the zero position of the transmitter should be adjusted to the standard value after installation and fixation.
 
7. Transmitter output ≥20mA?
Answer: The possible reasons are:
       A. Check whether the actual pressure exceeds the selected range of the pressure transmitter;
       B. Caused by overload of the sensor (severe overload sometimes damages the isolation diaphragm);
       C. Sensor failure;
 
8. The FST500-202 electronic pressure switch is not pressurized and the display is not zero?
Answer: The possible reason is that the display of non-pressurization is not zero.
       A. After the product is installed, there may be slight pressure on the equipment, which is not completely released;
       B. Whether the sensor may be blocked by the pressure hole and the residual pressure is not completely released;
       C. The zero position of the product has not been adjusted properly. After confirming that there is no pressure, press and hold the S1 button of the product for zero adjustment;
 
9. How to distinguish whether the analog output of FST500-202 electronic pressure switch is consistent with the pressure display value?
Answer: The analog output is divided into voltage and current.
      For 0-5V output, the signal has a value change of 5V. For products with a range of 160Bar, the pressure display corresponds to the value = analog output value*160Bar/5;
      If the analog output value is 2.5V, then the actual display pressure value is 2.5 *160/5=80Bar, then the display pressure value corresponding to the pressure switch is 80Bar;
      4-20mA output, the signal interval has a value change of 16mA. For products with a range of 160Bar, the pressure display value = (analog output value-4mA);
*160Bar/16 If the analog output value is 8mA, the corresponding display pressure value is (8-4)*160Bar /16=40Bar. When the measured output value of the product is 8mA, the corresponding pressure display value is 40Bar.
 
10. What is the alarm control of FST500-202 electronic pressure switch?
Answer: The electronic pressure switch is equipped with two alarm modes, which the user can set according to their needs;
      If the user chooses the relay alarm output mode, he can set and control one output mode, S1 switch point;
      If the user chooses the transistor alarm output mode, two output modes can be set to control, S1 and S2 two switching points;
      Control output:
      The control mode of the relay is pull-in and disconnection;
      The control mode of the transistor is high level (input voltage -0.7V) and low level;
      Upper limit alarm and lower limit alarm:
      S1, S2 set the alarm value, r1, r2 alarm recovery value;
      The first channel S1>r1 upper limit alarm (S1≠r1), S1＜r1 lower limit alarm (S1≠r1);
      The first channel S2>r2 upper limit alarm (S2≠r21), S2＜r2 lower limit alarm (S2≠r2);
      (See the introduction of FST500-202 electronic pressure switch manual for details)
 
11. Matters needing attention and maintenance during the use of pressure sensors and transmitters.
Answer: Matters needing attention during use.
      The correct installation position of the transmitter on the process pipeline is related to the measured medium. In order to obtain the best measurement effect, several points should be noted.
       1. Prevent the transmitter from contacting corrosive or overheated media;
       2. When measuring liquid pressure, the pressure tap should be opened on the side of the process pipeline to avoid sedimentation and slag;
       3. Prevent dross from depositing in the duct;
       4. When measuring gas pressure, the pressure tap should be opened at the top of the process pipeline, and the transmitter should also be installed on the upper part of the process pipeline, so that the accumulated liquid can be easily injected into the process pipeline;
       5. When measuring steam or other high-temperature media, a condenser such as a buffer tube (coil) should be connected, and the working temperature of the transmitter should not exceed the limit;
       6. The pressure guiding tube should be installed in a place with small temperature fluctuations;
       7. When freezing occurs in winter, the transmitter installed outdoors must take anti-freezing measures to prevent the liquid in the pressure port from expanding due to icing and causing damage to the sensor;
       8. When wiring, pass the cable through the waterproof joint or flexible tube and tighten the sealing nut to prevent rainwater from leaking into the transmitter housing through the cable; the ninth point is the installation of the transmitter when measuring the liquid pressure The location should avoid the impact of liquid to avoid damage to the sensor due to overpressure;
 
12. What kind of capability does the stability of the sensor indicate?
Answer: Under the same conditions and a long period of time, its input and output characteristics cannot change.
 
13. According to the nature of the sensor output signal, how many types of sensors can be classified?
Answer: There are three types: switch type, analog type and digital type.
 
14. The key points of pressure sensor purchase-sensor
1. Pressure sensors and transmitters generally measure the pressure of fluids (such as liquids, gases, and melts). Commonly used units of pressure are: Pa, KPa, MPa, bar, etc. Each pressure sensor and transmitter has a certain pressure measurement range, and the maximum pressure value that can be measured is called the range.
2. The output signal of the pressure sensor is generally a voltage signal in mV (millivolt). The size of the signal output is directly related to the voltage of the power supply to the pressure sensor. The output of most sensors is 1-2mV/V. That is, when the pressure of the measured medium reaches the maximum nominal pressure of the sensor, if the power supply to the sensor is 1V, the output signal is 1-2mV. Similarly, if the power supply to the sensor is 10V, the output signal is 10---20mV.
3. The output signals of pressure sensors are commonly used: 4--20mA, 0---20mA, 0---5V, 1---5V, 0.5---4.5V, 0---10V, RS485, RS232 and so on. The signals are all standard, and the output size is only proportional to the pressure of the measured medium. Within the rated voltage range, the output will not change with the change of the power supply. Commonly used frequency converters, plc, control display instruments, etc., its signal receiving module can receive these kinds of standard signals.
4. In order to feel the pressure of the measured medium, pressure sensors and transmitters have threads or flanges to connect with pipes or containers.
5. Range, signal, and connection thread are the three elements that must be figured out before buying pressure sensors and transmitters. After a sensor is completed, these three elements cannot be changed.
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