Development of a PLC based gas warning system in a surface coating factory
Nowadays proper life protection is very important for labours who are working in plants. In a surface coating factory life threatening toxic gases are used as raw materials or can be formed during the production as a by-product. Continuous measurement and monitoring of these gases is an important task because if they exceed a certain limit, a protection system needs to respond immediate by starting ventilation with light and sound alarms to prevent threatening humans. Such system must assemble the remotely measured values of the concentrations of these gases and evaluates them. These values must not exceed their limits determined in the proper laws and standards. Furthermore storing these values allow checking the environment later.
My task is to establish a gas warning system which continuously measures and stores the concentration of each type of gases. If one of them crosses the limit the system make sound and light signal, which indicates that a specific area of the plan is under danger. Many of these toxic gases are colourless and odourless, that is why people may not notice them in time.
To implement such system, first we have to examine what kind of gases generated in the plant, what are their properties and the most important question is why and how they are threat to human life. There are two ways of measuring gases: directly or indirectly. We have to examine, which measurement method can be used in a specific type of gases and what kind of sensors can determine the concentration of these gases in air. We need to know how these sensors operate and what kind of information can be obtained from them. Furthermore knowledge of relevant law is essential, because people’s lives depend on the system.
Next step is get to know the whole control system and methods for processing of measured data. I have to analyse the process and deduct the correct conclusion from the extracted information. I also have to specify where the sensors and alarm will be established. It is important that every person staying in a dangerous area can easily see and hear the alarms when the threat is exist.
After learning the structure of the system I have to implement a control system using Siemens TIA Portal environment. This means the processing and storing measured data and in addition communicating with an HMI operator interface.
Finally, I have to test the system and I have to be sure that the system is working properly.