Setting of alarms in the methanol section

In accordance with the requirements of GB 50493-2009 Code for Design of Detection and Alarm Systems of Flammable and Toxic Gases in Petrochemical Industries, alarm systems should be installed for carbon monoxide (toxic) as well as for flammable gases such as hydrogen and methanol. Of course, the deployment of alarms for toxic and flammable gases is still determined based on the source of the leak.

Assume it is flammable; due to the low alarm threshold, detection of toxicity can also be taken into account simultaneously

1# Pei Yuming: Please, the original poster, select the appropriate devices in accordance with the relevant provisions of GB50493-2009 \"Code for Design of Detection and Alarm Systems for Flammable and Toxic Gases in Petrochemical Industries\": 3.0.1 In areas where processes involving the production or use of flammable and toxic gases take place, as well as in storage and transportation facilities, detectors for flammable gases and detectors for toxic gases should be installed in accordance with the following rules: When there is a leak of flammable gases or flammable gases containing toxic substances, and the concentration of flammable gases may reach 25% of their lower explosive limit, but the concentration of toxic gases does not reach their maximum allowable level, then detectors for flammable gases should be installed； When toxic gases or toxic gases containing flammable gases leak, the concentration of the toxic gases may reach the maximum allowable level; however, as long as the concentration of the flammable gases does not reach 25% of the lower explosive limit, toxic gas detectors should be installed ； 3 In areas where flammable gases and toxic gases are present simultaneously, and where the concentration of flammable gases may reach 25% of the lower explosive limit while the concentration of toxic gases may reach their maximum allowable levels, separate detectors for flammable gases and toxic gases should be installed.

The key is to look at the process: what gases are involved and what are their properties? Next, it’s necessary to consider the risks: how frequent are leaks (the probability of them occurring) and what are the consequences? Only then can a decision be made.