May I ask about the situations where gland heads are used and where explosion-proof flexible hoses are used?
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My area’s explosion protection rating is EXdIIBT4; the installation uses explosion-proof distribution boxes, and galvanized pipes are used to connect the distribution boxes to the instruments. Currently, sealing is achieved at both the distribution box end and the instrument end using gland fittings. The safety inspection expert came and said it wasn’t acceptable; explosion-proof flexible hoses had to be used. The drawings from the design institute do not include any installation standards for this aspect. Under what circumstances is it necessary to use flexible pipes, and under what circumstances can threaded fittings be used?
As long as explosion-proof flanges are used at both the distribution box end and the instrument end.
Generally, for connections from field instruments to junction boxes, if armored cables are used, explosion-proof sealed connectors and 50x50 size raceways are chosen; whereas if unarmored cables are used, explosion-proof flexible connectors and galvanized protective pipes are selected. It’s a problem using a threaded fitting followed by a galvanized protective tube; the best solution is to replace the threaded fitting with an explosion-proof flexible connection tube.
It is recommended to use explosion-proof flexible connectors outdoors to protect the cables； Gran seal joints can be used indoors.
Does your Gran unit have an explosion protection rating and an explosion protection certificate number? If so, it meets the discontinuous protection standards; of course, it’s best for the cable to be armored, otherwise what they say is correct.
Refer to HG/T21581-2012, which contains examples of various connection methods; a split connection is allowed, provided that explosion-proof fittings are used
You can refer to this post: http://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1250505&extra=&page=1. We use explosion-proof flexible conduits in our explosion-proof applications
Are there any photos from the scene? The safety inspection expert suggests using explosion-proof winding tubes from the perspective of protecting the cables; it’s fine to add gland fittings at both ends. A newly developed tube-type explosion-proof cable introduction device by our company. You may ask for advice.
Previously, the standard was to use explosion-proof flexible hoses; nowadays, guards and explosion-proof sealing joints are used instead. Flexible hoses are useless – they allow water to get into the gauge easily, leading to problems. As long as it is an explosion-proof sealed joint, it’s fine