What are the requirements for positive pressure ventilation?
Thread Content
Currently, there are some hazardous locations where the electrical equipment uses non-explosion-proof motors, or where the electrical equipment in the control rooms is not explosion-proof and is located within those hazardous areas. What are the basic requirements for using positive pressure ventilation? Do tests still need to be done at the same time?
It is clearly stipulated in GB50058 \"Code for Design of Electrical Installations in Explosive and Flammable Environments\", GB50160 \"Code for Fire Protection Design of Petrochemical Enterprises\", and HGT20508 \"Regulations for the Design of Control Rooms\"!
The design of the control room for positive pressure ventilation is quite complex, and there are several key points that need to be understood. Make the volume of the control room as small as possible, so that the air flow required is lower. . The doors and windows of the control room must have good sealing properties to maintain a slight positive pressure inside the room over the long term. . Monitoring equipment should be installed to ensure a slight positive pressure inside the area compared to the outside, and combustible gas detection alarms should also be set up indoors. . The ventilation openings in the control room should draw air from non-explosion-proof areas.
The above is already quite comprehensive; as an additional point, a protective mesh should be installed at the fan inlet to prevent foreign objects from entering and causing a short circuit.
Yes, another thing to arrange is a safety interlock device for indoor pressure and the fan; the supply fan should be equipped with dual power supplies. Positive pressure ventilation is easy to talk about, but difficult to implement.
Personal understanding: 1. Generally, high-voltage motors are difficult to make explosion-proof; positive pressure ventilation is used as an explosion prevention measure. 2. Some of the control cabinets on site, such as the circuit breakers and contactors inside them, cannot be made explosion-proof; therefore, positive pressure ventilation is used for these control cabinets. 3. In the on-site control room, since many of the electrical equipment and instruments located there cannot be made explosion-proof, positive pressure ventilation is employed in the control room. The requirements for positive pressure ventilation of electrical equipment can be based on GB 3836.5-87, Electrical equipment for explosive atmospheres – Positive pressure electrical equipment. The requirements for positive pressure ventilation in control rooms can be referred to in Article 2.6.4 of the \"HG/T20508-2000 Specifications for the Design of Control Rooms\"