How to use Gran?
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Hello everyone. In our newly built factory, the instrumentation and electrical design does not use the original explosion-proof flexible pipes to connect the field instruments to the galvanized pipes; instead, the design specifies explosion-proof flanges. A section of the instrument cable will be exposed between the galvanized pipe and the on-site instrument. So I have two small questions. First: What are Gran’s standards? Won’t the safety inspection fail? Are there any specific, verifiable relevant standards? For example, which specification states that explosion-proof glands can be used and that cables can be exposed? Second: In terms of explosion-proof glands, are there any special requirements for instrument cables? For example, cables dedicated to Gran. Or can we just use a cable similar to a flexible tube? Thank you all for helping me look for it. Thank you
In explosion-proof areas, armored explosion-proof glands are generally used, and cables should be steel-wired armored to prevent mechanical damage. The manufacturer’s instructions for Gran head specify an explosion-proof rating requirement.
Explosion-proof glands serve as a barrier between flameproof equipment and explosive environments. Cables with or without armor can be used, but there are differences; this should be clarified at the time of purchase. In the early days, only explosion-proof flexible pipes and galvanized steel pipes were used; it was non-compliant to do so without adding explosion-proof isolation seal joints (commonly known as elbow connectors). At present, your factory achieves explosion protection simply by using explosion-proof glands, without the need to add additional explosion-proof flexible pipes.
Thank you for your answer. I was wondering if there are any relevant technical specifications or something like that
It won’t work; a gland head is necessary, but the cables still cannot be exposed. The reason your cables are exposed must be that the wires at the connectors don’t match. Re-purchase the corresponding connectors and connect them. Exposed cables are prone to damage, which means they are no longer explosion-proof. Safety inspection will let you pass today, but not tomorrow either. You need to be ahead of safety inspections, rather than just focusing on making corrections.
What you have here is called a disconnectable connection; it’s not clear whether it can be used in explosion-proof areas. If the standards or specifications cannot be found, you can consult your design firm.
It can be used in explosion-proof areas, as well as in the petrochemical and oil industries; this type of wiring is employed in such contexts. However, the cables required are armored cables, as exposed cables need to be protected from mechanical damage
When the safety supervision agency conducts an inspection, it is possible that they will require you to make corrections. Different inspectors have different requirements. You can also raise concerns regarding matters related to the design firm; often, the design firm communicates with the suppliers as well. However, the owner cannot let them do whatever they want – raise these issues directly during the review of the drawings
There are many types of stainless steel cable connectors, nylon cable clamps, metal conversion connectors, and armored explosion-proof gland fittings; you need to choose the appropriate one based on actual requirements and operating conditions. The standards that are commonly applied include: EN50262/UL514B for overall requirements; EN60529/DIN40050/IEC60529 for overall protection performance standards. For explosion-proof products, the applicable standards are IEC60079-7:2001, GB3836.1-2000, IEC60079-0:2004, GB3836.3-2000, and IEC60079-1:2007, GB3836.2-2000. The electromagnetic compatibility standard is IEC61000-4-1-2000
The explanation here is very comprehensive: https://mp.wei*n.qq.com/s/hADTRWUL6PtbxAeopYtr5w
I’ve encountered this situation before: the thermometer was too close to the temperature transmitter on site, perhaps about the length of 3 hoses. The factory managers simply skipped using hoses and connected them with wires instead. I asked the design institute, and they said that in such cases, explosion-proof armored wires must be used.