Matt Ogden, Cable Gland Product Specialist at Hawke International, the leading manufacturer of glands for harsh and hazardous environments, discusses the limitations of using glands with metallic compound pots, and the benefits delivered by transparent, non-metallic alternatives.
In hazardous environments, every item of equipment – no matter how small – must successfully play its part. This absolutely includes cable glands, tasked with protecting extremely expensive machinery. But cable gland strategies are too often overlooked.
This is a mistake. Cable glands are not commodity products, not mere bits of brass and rubber. Indeed, there have been some recent developments with the development of non-metallic compound pots, which could have a profound effect on organisations working in hazardous environments. So let’s take a closer look at the merits of non-metallic compound pots for cable glands compared to more traditional, metallic pots.
The benefits of these new compound pots can be seen in terms of installation, inspection, and overall safety.
Installation
When installing a metallic compound pot, it’s not possible to see the resin. This removes an element of control from the installer. When potting a non-metallic pot, such as a silicone alternative, this problem is avoided as the resin is visible. This means that any issues such as voids or underfilling can be immediately addressed before the compound cures; not a possibility with metallic pots.
Inspection
Also, to inspect a traditional compound pot, one made out of brass for example, you need to cut the pot off the resin. That’s because you can’t see what’s going on inside glands with metallic pots. But clearly, the issue here is that in doing this, you destroy the sample. Put simply, after inspecting a metallic cable gland, it needs to be remade!
Cable glands with clean compound chambers that allow full visibility during inspections solve this problem. The resin is observable in-situ and so glands can be inspected accurately and quickly without the additional time and money associated with inspecting (and remaking) a traditional metallic pot. If any issues are spotted, they can be addressed straight away.
Flame Paths
In addition to these installation and inspection benefits, non-metallic pots boast superior health and safety credentials. Traditionally, metallic pots rely on maintaining flame path clearances between a gland and the pot itself. These flame paths are designed to dissipate energy and prevent anything igniting – something that must be avoided at all costs in hazardous environments, especially in potentially explosive zones. However, if the clearance becomes too large, perhaps due to machining tolerances, there is a risk of ignition. Certainly, if a flame path is compromised with a metallic pot, the cable gland is no longer compliant and no longer safe; it’ll have to be discarded.
Non-metallic pots, on the other hand, can be compressible. In this case, there’s no need to rely on controlled clearances or flame paths to reduce the ignition risk. This is not to say that damage can’t still occur. But, if it does, you can simply cut the pot off and replace it without needing to replace the whole gland – not the case with metallic types.
Conclusion
Historically, metallic components have been favoured when it comes to designing compound pots for cable glands, and the issues encountered regarding installation, inspection and repairs have just been accepted as par for the course. Now however, we’re seeing a shift in thinking and exciting new options for businesses with the rise of non-metallic pots. This presents a huge leap forward for decision-makers considering cable gland strategies, as accurate installation is now easily attainable, inspection is simplified and unparalleled safety benefits are provided, all while reducing costs in the process.
For more information and to read about Hawke International’s new world-first cable gland range with NEC® compliant, fully transparent, non-metallic pots, visit:
https://www.hubbell.com/hawke/en/NEC-Compliant-Glands
