25 Jul Explosion Proof Glands Installation: “Anti Wine Cork” Method
Canary HLE President,
Hazardous Locations industry expert
Courses are led by Brian Schneider, a Hazardous Locations industry expert with over 20-years experience working with clients including Lockheed-Martin and Siemens. He specializes in intrinsic safety and flame-proof/explosion designs and evaluations. Brian is a 12-year member of the Canadian Electrical Code (CEC) Section 18 Committee and has designed and built testing labs in Canada and Europe.
All Certified Flameproof/Explosion proof glands that use a sealing compound around the wires have one thing in common. They all have, what I have termed, an “anti wine cork” mechanism.
Wine corks are “friction fitted” which keeps the cork in place until such time that it is removed. The corks serve their function well as indicated by the many years that they have been in use. However, Flameproof/Explosion proof glands cannot rely on friction fitting. Instead, “mechanical stops” are machined into the units to prevent the sealing material from moving or shifting should an explosion occur (see Figure 1). Failing to install the correct depth of sealing material does not engage the stops (see Figure 2). Therefore, sealing material is relying on the friction fit and wires to maintain the potting in place during an explosion within the enclosure.
Conduit seals also require mechanical stops for the same reason.
Figure 1: Correct Potting Form (Source of illustration: Canary HLE)
Figure 2: Incorrect Potting Form (Source of illustration: Canary HLE)
Note: The damning/packing fiber has been left out of Figures 1 and 2 in order to show the potting forms.
Figure 3 illustrates a conduit wire sealing system with non-asbestos packing fiber being used for the stopping points (Source: J. W. Taylor, E. Cheney and P. Pace, “The advantages, challenges, and critical aspects to achieving robust seals within hazardous location electrical installations,” 2017 Petroleum and Chemical Industry Technical Conference (PCIC), 2017, pp. 79-88, doi: 10.1109/PCICON.2017.8188726).