Solving the problem of non-explosion-proof large motors in explosion-proof areas
Thread Content
The safety supervision agency has inspected our factory on several occasions and raised concerns regarding the fact that multiple large motors in use are not explosion-proof. However, replacing these large non-explosion-proof motors (such as those used in ammonia refrigeration units or 5000KW hydrogen-nitrogen compressors) would involve significant costs. Experts from the safety supervision agency mentioned that Article 50058 states that positive pressure ventilation can be used to convert areas into non-explosion-proof zones; yet after conducting further research, it was found that there are also strict requirements regarding positive pressure ventilation. Therefore, I would like to ask the experts: are there any specific requirements and standards for converting explosion-proof areas in a factory into non-explosion-proof areas? Is it possible to provide positive pressure ventilation only for the motor and control box? Are there any specific PPTs or examples recommended? reward_7ree
First, it is necessary to understand why this area is a blast-proof zone – is it because the concentration of flammable and explosive gases exceeds the specified levels? If so, ventilate the workshop, that is, maintain positive pressure
A fully enclosed cement wall is built to completely isolate the equipment from other devices; forced air supply is provided from a distant, non-explosion-proof area using centrifugal fans, and flame arresters are installed at the exhaust outlets.
I have a question, OP: Are the equipment in your factory not meeting explosion-proof requirements due to their age, or was the original design not built to such standards, or did it result from subsequent expansion and renovation efforts? First, we need to figure out the reason for this hidden risk before we can come up with a solution for you. Not all of the methods proposed in 50058 can be used.
The original poster did not clarify your actual situation. In the past, regulations regarding explosion protection for systems involving ammonia were not strict. Ammonia is lighter than air and has a strong pungent odor; its explosive range is 15.5% to 27%. According to the current standard **“Code for Design of Electrical Installations in Explosive and Flammable Environments” GB 50058**, which stipulates that explosive hazard zones should be determined based on the level of the source of emission and ventilation conditions, ammonia compressor rooms can be classified as Zone 2, with the zone classification to be adjusted according to the ventilation conditions. It is recommended to find a professional design firm with reliable credentials; they will identify appropriate corrective measures and prepare design plans. You can then submit these plans to the safety supervision agency for approval, and once approved, carry out the necessary corrections according to the plans
The design institute’s drawings did not include any provisions for explosion-proof areas, let alone the design of explosion-proof motors. I asked experts whether it was possible to avoid replacing the motors, but they said it was not possible. They suggested that if the design institute issued a certificate stating that the factory area had positive pressure ventilation, then they would accept that solution. In other words, the design institute would have to take responsibility for this
Strictly speaking, you should have a dedicated safety design document before putting the system into operation. This document must be reviewed and approved by experts recognized by the safety supervision system (there are specific regulations regarding such reviews), and it is also necessary to comply with the principle of simultaneous implementation of safety measures, something that you seem not to have done properly
I’m begging for some wealth points; I need to download 3836
Exhaust fans can be installed within the area; additionally, ventilation ducts can be added to draw in outside air and blow it toward the equipment through these ducts.