A brief discussion on ERS system and applicable liquid level gauges

　　ERS (Electronic Remote Sensor) electronic remote transmission system solves common problems in level measurement on high containers and towers. The ERS system is a multi-parameter system that provides additional process optimization control information. In addition to level calculation, ERS provides real-time access to readings from each pressure sensor and proportional output of level or volume measurement. Since the ERS system is so closely related to level measurement technology, what are the level meters suitable for the ERS system? Before introducing it, let's first understand what the ERS system is.

　　ERS is a new type of differential pressure level measurement system. The ERS system consists of two ordinary pressure transmitters connected by cables (CAN communication) to form a differential pressure measurement system. The calculation of differential pressure is completed by the field transmitter. The main meter directly outputs the differential pressure signal. Only a 4mA~20mA loop is required to connect to the main meter, and the sub-meter is powered by the main meter. The ERS system uses patented synchronization technology to directly adjust the differential pressure zero point of the main meter to ensure reliable synchronization of the differential pressure signal. In addition, ERS technology is a supplement to the traditional double flange liquid level measurement, and has its own characteristics and advantages. For example, when using a double flange diaphragm transmitter to measure the liquid level, if the pressure interval is too large and the capillary length is too long, a series of problems will arise. Common problems include: when the capillary is too long, the temperature change has a greater impact on the measurement accuracy, the response speed will also be slower, and the high-temperature oil needs to be heated when the ambient temperature is too low. However, ERS technology can just make up for the shortcomings of double flange liquid level measurement in these cases. Since the ERS system has such obvious advantages, can it be used in all working conditions? The answer is no. Generally, the ERS system is applicable to the following four working conditions:

　　1. For high storage tanks and towers, such as distillation towers, fermentation tanks and other equipment with high heights. Since the distance between upper and lower pressure measurements is relatively large, the use of the ERS system can effectively eliminate the measurement error of long capillaries, shorten the response time and improve the overall measurement performance.

　　2. Working conditions with large differential pressure and small static pressure. ERS calculates differential pressure by measuring pressure. To ensure the accuracy of differential pressure signal, the ratio of static pressure SP to differential pressure DP cannot exceed the minimum accuracy requirement of the transmitter, that is, (SP+DP): DP＜100:1. If it is within 30:1, the effect will be better.

　　3. In situations where there is a large ambient temperature difference or heating is required: Since ERS does not require a pressure pipe or capillary tube, the influence of ambient temperature on the measurement can be fundamentally eliminated.

　　4. For complex installation conditions, ERS only needs to fix two transmitters separately and then connect the communication cables.

　　After understanding the concept of ERS system and its applicable working conditions, we have a certain understanding of ERS system. Next, let's talk about the liquid level gauges suitable for ERS system.

1. Radar level meter

Rada-21 high frequency pulse radar level meter

　　Radar level meter is a non-contact level measuring instrument based on electromagnetic wave technology. It mainly consists of three steps: transmitting, reflecting and receiving electromagnetic wave signals. The signal processor detects the time difference or frequency difference between the transmitted wave and the echo, and then calculates the height of the material. The radar level meter consists of several parts such as signal processor, antenna, display unit, etc. Due to its high accuracy and large measurement range, it is very suitable for ERS system. In addition, the characteristics and advantages of radar level meter also fully prove that it is very suitable for ERS system:

　　(1) It adopts non-contact measurement method, which is less affected by the physical and chemical properties of the measured medium and has a wide range of applications;

　　(2) The electromagnetic waves it emits do not require a transmission medium and can be transmitted in a vacuum, making it suitable for vacuum working conditions;

　　(3) Integrated design, no mechanical moving parts, good reliability, long service life and simple maintenance;

　　(4) Small blind area, large measuring range, high reliability and measurement accuracy.

2. Ultrasonic level meter

Uson-11 ultrasonic level meter

　　Ultrasonic level meters and radar level meters both use non-contact measurement methods to measure the liquid level of the medium. Their working principles are also similar to those of radar level meters, so they are also one of the ideal measuring instruments in the ERS system. The ultrasonic sensor transmits an ultrasonic pulse signal to the surface of the medium, and the medium reflects the echo. The echo signal is then received by the sensor. The intelligent converter measures the time difference between the sensor transmitting and receiving the pulse signal, and calculates the distance from the sensor to the surface of the medium based on the time difference and the speed of sound, and then calculates the actual liquid level based on the installation height of the sensor.

　　The ultrasonic level meter independently developed by Jiwei has the following characteristics and advantages:

　　(1) It is suitable for continuous, non-contact level measurement of corrosive, highly viscous, flammable, toxic liquids, slurries, sewage, etc., and is not affected by medium density, dielectric constant, conductivity, etc.

　　(2) Built-in temperature sensor to compensate for changes in sound speed caused by changes in the temperature of the propagation medium.

　　(3) It can be used to measure liquid level in open containers, pools, etc.

　　(4) High cost performance, long service life, high measurement accuracy, stable performance and strong reliability.