Regarding flammable and toxic gases and DCS systems

Generally, combustible and toxic gas alarm systems are installed separately

If the combustible gas and toxic gas alarm systems you are referring to are installed independently, there is no need to connect them to the DCS system, as the independent gas alarm systems can fully meet the requirements for providing alarm alerts. However, if it is desired to see these alarms on the DCS system as well, then integrating it with the DCS system is an option; this is not a principle issue, and project owners often request this as well. If you want to introduce gas detection signals and alarm functions into a DCS system, it is important to ensure that the controllers, displays, and IO cards within that system are all configured independently. If there is a SIS system in that device, it is best to feed these signals into the SIS. However, one thing to note is that if the gas detection system has interlock signals, they cannot be fed into the DCS; either it must be set up independently or integrated into the SIS to carry out the interlock function.

Actually, there is no need to introduce a DCS system, as alarm notifications can be handled through independent setups. Necessary interlock actions must be carried out whenever the levels of colored gases or toxic gases exceed the specified limits. If you want to incorporate gas detection signals and alarm functions into a DCS system, it is important to ensure that the controllers, displays, and IO cards in that system are all set up independently. If there is a SIS system in that device, it is best to feed these signals into the SIS. However, one thing to note is that if the gas detection system has interlock signals, they cannot be fed into the DCS; either it must be set up independently or integrated into the SIS to carry out the interlock function.

The key is to check whether there is an SIS system; if not, it is better to introduce a DCS system for display and alarm functions. Our company has adopted DCS displays.

Our company did not design the SIS system. The original design team’s approach was to create a separate system for flammable and toxic substances, to interlock it with the exhaust fans in each building, and to connect it to the DCS via communication lines for display purposes. Thank you all for your suggestions.

There is no need to connect to a DCSS. The reasons are as follows: 1. Such devices operate as independent systems, with their alarm panels located in the control room. 2. If the purpose of connecting to a DCSS is for display and alarm functions, then it is unnecessary, as the audio and visual alerts provided by the alarm panels are much better than those of a DCSS. Moreover, connecting from the alarm panels to the DCSS would require additional cables and AI cards. 3. If the goal is to enable interlocking between certain components, this approach is also questionable. Consider the situation where detection probes are spread throughout the area to monitor concentrations of potentially hazardous gases, but the location of leaks is unknown – how can interlocking be achieved in such a case? Therefore, unless there is a direct causal relationship, interlocking seems unnecessary. 4. Even when connected to an ESD system and an emergency stop is triggered by a hazardous gas alarm, extreme caution should be exercised

Refering to Article 3.0.10 of the \"Code for Detection and Alarm of Flammable and Toxic Gases in Petrochemical Enterprises\" SH3063-1999, the detection and alarm system for flammable and toxic gases should be a relatively independent instrumentation system. So it’s unnecessary; ordinary combustible gas detection alarms are usually interlocked with ventilation fans.

In a few large projects I’ve worked on, both combustible gases and toxic gases were integrated into the DCS system for display. Maoming Petrochemical, Qingdao Refining & Chemical, Huizhou Refining & Chemical

There is absolutely no need to create a comprehensive alarm system; one simple alarm is sufficient. When toxic or harmful gases are detected, a digital signal is sent to the DCS system to alert operators to which location there is an alarm, so they can check the gas monitoring system.:lol

Introducing DCS facilitates operation by workers