An explosion proof cable gland protects the one part of a flameproof enclosure that cannot be welded shut. Every other joint on the box is machined and sealed at the factory. The cable entry is opened on site, by an installer, with a spanner — and if that entry does not carry the same protection concept as the enclosure, the certificate stops at the wall.

This guide covers what an explosion proof gland actually does, why IP68 and “explosion proof” are two unrelated claims, and the four compatibility checks that decide whether a correctly installed gland is still the wrong one. For the wider family of cable entries, start with our cable gland hub.

What an Explosion Proof Cable Gland Actually Does

An explosion proof gland does not prevent an explosion. It is not indestructible, and it is not a filter. It closes the last opening in an enclosure that is already designed to be sealed, and it does that in three separate ways:

• It contains an internal ignition. Flameproof design assumes fuel will get inside the enclosure and an arc will light it. Once the pressure wave starts, the flame has one place to go — the cable entry. The gland is built so the only route out is a long, narrow, machined gap.
• It keeps the fuel out. The same gland seals the entry against gas, vapour and dust, so the atmosphere never reaches the ignition source. Containment and exclusion are separate functions on separate surfaces.
• It holds the cable still. A gland that allows the cable to move under vibration will eventually wear its own seal open.

The flame path is worth understanding in one sentence: hot gases forced through a long, narrow gap lose heat to the surrounding metal and leave below the auto-ignition temperature of the gas outside. The width and length of that gap are set by gas group, which is why a gland certified for a mild gas group is not interchangeable with one certified for hydrogen. Our GHX CMP explosion proof gland range shows how those components are arranged in practice.

Two Different Jobs, Two Different Certificates

Most specification errors in hazardous areas begin by treating two certificates as one. They are not related, and one does not imply the other.

A gland can carry IP68 and hold no Ex certification whatsoever. That is the ordinary case for a standard waterproof gland. The reverse is just as normal: an increased safety gland rated IP66 is perfectly compliant, because Ex e protects by sealing and mechanical integrity rather than by flame containment.

The practical consequence: an IP68 line on a datasheet tells you the gland will survive washdown, flooding and hose-down cleaning. It tells you nothing about gas group, temperature class or equipment protection level. If the enquiry only says IP68, the gland that arrives may not be permitted in the zone at all. Sizing an IP rating correctly is a separate exercise, covered in how to choose the right IP rating.

What Is Inside the Gland

Four surfaces carry the entire job. Lose any one of them and the other three do not compensate.

Sizing sits on top of all four. The most common field error is a gland chosen for the wrong cable diameter range, then tightened until it “feels” sealed. Compression seals have a working range for a reason. Outside it, the seal either crushes and splits or never contacts the sheath — and neither condition is visible after assembly.

The Four-Way Match: Why a Correctly Fitted Gland Can Still Be Wrong

An installation can be mechanically perfect and still be non-compliant, because Ex compliance is a match between four pairs of properties rather than a property of the gland itself. Check all four before ordering.

The third row is the one most often missed. A gland that is certified, correctly sized and correctly torqued is still the wrong gland if it is a compression type where the cable construction and enclosure volume call for a barrier type. Thread forms matter for the same reason — a tapered NPT thread and a parallel metric thread are not interchangeable, and the guide to cable gland thread types sets out which form goes where.

Protection Concepts and How to Read the Marking

Four concepts cover most cable entries. Each is a different way of achieving safety, not a quality grade.

Whatever is stamped on the body decodes the same way, field by field:

A marking such as Ex db IIC Gb carries all of that in six characters. A gland with no marking on the body has no certification to claim, however good the datasheet looks.

Temperature Class and Ambient Range Are Not the Same Number

These two figures get quoted interchangeably and they should not be. Temperature class is a ceiling on surface temperature, set by the gas: T6 caps it at 85 °C, T4 at 135 °C, T1 at 450 °C. The gas ignites above its auto-ignition temperature, so the equipment must stay below that ceiling in service.

Ambient range is a different constraint entirely. It is what the certificate permits for the environment the gland sits in, and it comes from the materials and seal elastomers rather than from the gas. A gland certified for a narrow ambient band does not become acceptable because the site gas group is easy. When an installation sits outside the certified band — offshore platforms in winter, or a foundry roof in summer — it needs a gland certified for that band, not a warmer or colder version of the same part number.

Materials and Where Ex Glands Are Used

Material choice is a corrosion decision first and a strength decision second, and it should be led by the site environment rather than by price.

Explosion proof glands are specified wherever an enclosure sits inside a classified area: oil and gas processing, refineries, chemical and pharmaceutical plant, coal handling with firedamp risk, grain and powder handling, and offshore or marine installations. Our stainless steel cable gland range carries the marine and offshore variants, including the PG63 gland for marine environments, and the brass cable gland range covers the general industrial cases.

Indicative Pricing and MOQ

Ex-rated glands cost more than standard glands because of the certification and the machining tolerances, not the metal.

FOB Ningbo or Shanghai, based on 300 pcs per size. Indicative only — final price depends on thread type, size and certification package.

The minimum order for Ex-rated glands is 300 pcs per size, against 1,000 pcs per size for standard brass and nylon ranges. Trial quantities from 100 pcs are possible on standard items; Ex items are not tooled, so that flexibility does not apply to them. Add the certification package to the order — ATEX and IECEx certificates, the IP68 immersion report to IEC 60529, and the material certificates for the brass or stainless steel used.

ЧАСТО ЗАДАВАЕМЫЕ ВОПРОСЫ

Is an explosion proof cable gland the same as a waterproof one?

No. Waterproof refers to an IP rating and nothing else. An explosion proof gland adds a protection concept, a gas group, an EPL and a temperature class. A standard IP68 gland is not permitted in a hazardous area.

What is the difference between Ex d and Ex e cable glands?

Ex d contains an internal explosion and cools the escaping gases through a flame path. Ex e prevents ignition by design and seals with high integrity. They are not interchangeable, and the gland must match the protection concept of the enclosure it enters.

Can a standard gland be used on an Ex enclosure?

No. Doing so voids the enclosure certification at the cable entry, which is the only opening not sealed at the factory. The enclosure and the gland are one system for certification purposes.

How do I choose the right size?

Measure the cable over the surface the inner seal actually grips, then select the gland whose certified range contains that figure. Never tighten a gland outside its range to make it fit.

Next Step

Send us the enclosure protection concept, the zone and gas group, the cable construction with its measured diameter, and the entry thread. We will come back with the matching gland, the certification documents and an FOB price for your quantity — see the full selection guide to cable gland types for the wider picture.