Instruments: [One Question per Week] Fourth Week of 2011

Hydrogen sulfide: Sample and analyze in enclosed or semi-enclosed environments; use a gas mask

I can only talk about my previous employer, the chlor-alkali PVC company; the highly toxic substances there are mainly chlorine and vinyl chloride monomer. (Note: Vinyl chloride monomer is not classified as a highly toxic substance in the List of Highly Toxic Substances (2003 edition)). For toxic, volatile liquids or gases, my former company installed alarm and detection devices for such hazardous gases; therefore regular inspections were carried out. As for installation or emergency maintenance, the company had relevant regulations in place, and the procedures followed by different companies were more or less the same: the main valves and branch valves were closed, the pipes or equipment were evacuated with nitrogen, or negative pressure was created using exhaust fans (the process seems to involve both blowing air in and extracting it). Once sampling showed no issues, work could begin.

Highly toxic substances are those that can cause severe damage to the body or lead to death even in amounts of less than 50 grams entering the human body, such as fluorine, hydrofluoric acid, phosgene, and carbonyl fluoride. Protective measures: 1. Wear a gas mask to protect against toxic gases ； 2. Rotate tasks to reduce the time spent in toxic gas ； 3. Improve local ventilation to reduce the concentration of toxic gases at the work site ； 4. Before entering toxic containers such as towers and storage tanks to carry out work, the container should be isolated from other equipment and pipelines using a blind flange, and then purged with an inert gas or steam. Then the manhole is opened and ventilated with a blower; entry is permitted only after it has been confirmed that all toxins have been completely removed. People entering the container to work must wear long-tube gas masks, with the ends of the tubes placed in an area outside the container where the air is clean. When a person is working inside the device, the supervisor must not leave at any time.

What I was exposed to was H2S. At room temperature, hydrogen sulfide is a highly toxic gas that is colorless and has an odor similar to that of rotten eggs. The gauge is used for measuring pressure. The measures to be taken when repairing or disassembling the gauge are as follows: wear a Type 4 gas mask, pay attention to the wind direction, and position yourself upwind. After removing the gauge from the device, it’s advisable to blow the connection tubes with steam, which can help remove any impurities and odors. Work should be carried out by two or more people, with a skilled technician present.

There are many toxic and hazardous substances in chlor-alkali plants! These include: chlorine gas, vinyl chloride gas, hydrochloric acid gas, and many others; generally, we wear gas masks or respirators!

We are a refinery, and the catalytic units produce highly toxic substances such as hydrogen sulfide gas. The protection measure is to use respiratory masks, but they aren’t used very often; for minor tasks, it’s done without wearing masks. There are basically no special methods for installation or maintenance. The MTBE produced in the gas-phase MTBE facility is low in toxicity, and methanol is also low in toxicity; it’s best to avoid direct skin contact, and rubber gloves are advisable. I’m not sure how to deal with the issue of inhalation – even a small amount inhaled can cause nausea, while slightly more can lead to vomiting and dizziness

Reply to 1# cnooczhouyx: Determine the proper escape direction and wear the appropriate gas mask

For installation: proper selection, installation standards, and successful acceptance. For routine maintenance: follow the maintenance procedures and use proper personal protective equipment. More importantly, the process must meet the conditions required for equipment handover before maintenance work can proceed; for example: (1) In toxic and hazardous areas, vacuuming is a crucial step. (2) In flammable and explosive areas, displacement and analysis are particularly important. One thing they have in common is: positive pressure operations must be avoided at all costs. In abnormal situations such as emergency repairs, experience from drills may be necessary as a safeguard; qualities such as a calm mind, thorough consideration, decisive decision-making, and prompt action are essential. Regarding the flash explosion incidents reported in the media recently, it would be a great shame if they were caused by human-induced fires, after all, the combustible gas alarms had already issued warnings in advance. In this regard, it is more valuable to have experts in process engineering delve into the matter. . .

We used to have an acrylonitrile plant here, which has been shut down for several years now. An allergy test injection is required every year, and those who show a reaction cannot work on this device. For those who work on instrument maintenance, wear gloves, safety goggles, and work clothes, and follow the operating procedures. There are no special protective measures. To be honest, in the chemical industry, there are few products or semi-finished goods that are non-toxic, from the raw materials used in production all the way through. There are always some toxic and harmful gases in the air, yet many people still have to work here. It is beneficial to drink milk every day.

I have mainly been exposed to chlorine and hydrogen sulfide. As an instrument maintenance worker, I carry a portable detector when conducting routine inspections in the designated areas, so that I can respond promptly in case of an alarm. During maintenance work, I usually wear an air respirator before entering the area where the work is to be carried out