Performance Case
Factory Service Facility GAS/Chemical System

Improvement of PLC signal of gas detector in anaerobic zone

PLC automatic detection in anaerobic zone


This time I want to share with you the case of a customer in the optoelectronics industry. The required factory is located in the anaerobic area of ​​the wastewater field. This case uses a large number of gas detectors, and the factory system information needs to be transmitted across regions.
In the underground tank of a confined space, the water treatment process will not only reduce oxygen, but may also generate various gases such as: methane CH4, hydrogen sulfide H2S and other …… dangerous gases, so gas detectors play a very important role in this case .


Difficulties encountered by customers

In the wastewater treatment process in the anaerobic zone, gas detectors must be used to monitor the oxygen concentration, and the oxygen concentration information needs to be transmitted across regions. This part is originally based on the use of the signal distributor AI output to transmit the information. However, the signal distributor has a high probability of failure in use, which caused a lot of trouble in their operation. Therefore, the customer later replaced it with a detector that can output multiple sets, and asked Longzhong to help improve the signal transmission problem.


Longzhong provides solutions

Oxygen concentration data needs to be transmitted across regions. Longzhong engineers re-planned and designed the transmission line according to the layout of the new detector, and optimized the signal return function of the gas detector.
In addition, Longzhong's engineers also replaced the original owner's way of using a signal distributor, and switched to a PLC programmable controller to connect the MODBUS TCP network backhaul, using Ethernet communication to make its network topology structure. more flexible. In this way, the information returned is less error-free, and the status of the detector and which circuit board the detector is connected to can be clearly grasped, and the signal transmission quality is more stable and less likely to be disturbed.


When the value of the detector is abnormal, in order to protect the life safety of the personnel and grasp the emergency repair time of the system, the system safety chain will be activated, and there will be a voice alarm broadcast in the factory area. If such a large motion alarm is used in daily maintenance and testing, it may cause trouble to the operation in the factory. Therefore, you can see the display of "Isolation" of the detector in the factory area on the map control. There are two reasons:
1. The gas detector is undergoing routine maintenance/calibration.
2. There is a problem with the detector, which needs to be repaired.
This part can be manually marked and isolated by personnel to avoid false transmission of alarms, and these information can be clearly transmitted across regions after integration through PLC control.


Gas detector PLC signal improvement


There are many industries that have needs for wastewater treatment. Among them, the optoelectronic industry and the semiconductor industry require more complicated procedures for wastewater treatment due to product process factors. The use of PLC control points through Longzhong can not only provide more stable transmission quality, but also collect and integrate the detector status information, so that the factory personnel can see it at a glance.


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