Is an explosion-proof sealing box an essential component for instruments in explosion-proof areas?

Explosion-proof sealing boxes are not necessary in some applications, depending mainly on the site conditions and safety requirements. If the explosion-proof gland already meets the requirements for explosion protection and sealing, then there may be no need to use an additional explosion-proof sealing box. It is recommended to consult relevant professionals or check the specific safety standards and regulations to ensure the security and compliance of the system. .

A transmitter plus a gland is sufficient; use mortar or rubber plugs at the cable ducts or tray openings. Armored cables can be used to address cable issues.

I haven’t even found this thing in any specifications

I’m posting and upvoting myself; I hope experts who happen to pass by can offer some advice

What is an explosion-proof sealing box? Wire gland? My standard approach is to use a transmitter + explosion-proof flange with internal threads (sealed) + explosion-proof flexible tube (unsealed) + galvanized pipe (unsealed).

The continuous protection system mentioned in the self-control installation manual HG/T 21581 also does not refer to explosion-proof sealing boxes. I understand that as long as either the flange or the flexible tube provides a sealing function (usually the flange does the sealing).

It’s a Y-shaped wire gland that can be filled with glue; it seems to be a product that doesn’t come with a gland fitting. I haven’t seen this type of thing used much before, but the company has continued to use it. Now we want to eliminate it and are looking for any theoretical basis for doing so, after all, it’s been in use for many years.

A standard was indeed found. Section 5.3.4 of the national standard GB-50257-2014, \"Code for Installation of Electrical Installations – Construction and Acceptance Specifications for Electrical Installations in Explosive and Fire-Hazardous Environments\", stipulates that for steel pipe wiring in explosive environments classified as Zones 1, 2, 20, 21, and 22, isolation seals must be installed, and the following requirements must be met: 1. Isolation seals shall be installed at the entry points of electrical equipment that do not have built-in sealing devices. 2. During normal operation, the area within 450 mm of all ignition source enclosures shall be isolated and sealed. According to 8.4.7 of the SHT3521-2013 – Technical Specifications for the Construction of Petrochemical Instrumentation Projects, when connecting the protective tube to components such as local control panels, instrument boxes, wiring boxes, and conduit boxes, sealing measures must be taken, and the tube must be fixed securely. The inlet ports for instruments and instrument equipment should be sealed using cable sealing joints. The isolation seal mentioned here should refer to the explosion-proof flange, right?

Yes, the explosion-proof gland you mentioned is indeed one of the devices used to achieve isolation sealing. According to the national standards GB-50257-2014 and SHT3521-2013 you cited, it is indeed necessary to seal the power inlet of electrical equipment in specific hazardous environments to ensure safety. Explosion-proof gland fittings can clamp the cable and provide a seal, thereby preventing potential sparks or flammable substances from entering the equipment. If the explosion-proof gland already meets the requirements for isolation sealing specified in the standards, then it may not be necessary to use an additional explosion-proof sealing box. However, the specific details still need to be determined based on the actual application environment and the specific requirements of the device. It is recommended that you consult relevant professionals or security audit agencies further to ensure compliance with safety standards while also optimizing costs. .

This description refers to the situation where there is no isolation joint between the explosion-proof flexible tube and the instrument; in other words, the flexible tube and the equipment are considered to be connected. In such a case, an additional isolation device must be installed at the other end of the flexible tube to ensure sealing.