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Barrier glands Armour clamps
A barrier gland is an Ex d cable gland Armour clamps have traditionally been armour
incorporating a compound filled chamber specific, which is to say that a gland would
sealing around the individual cores of the cable require a different armour cone/ring arrangement
to maintain the Flameproof integrity of the for each type of armour it could accommodate,
equipment into which it has been fitted. A barrier this created many logistical problems. Peppers’
gland must be used where the standard method solution has been the development of a
of glanding (elastomeric seals) an Ex cable entry “universal” armour clamp that caters for all
is considered unlikely to maintain the integrity of armour types. We discovered that by extending
Flameproof equipment and contain an explosion the length of the cone and reducing the taper
within the enclosure due either to: angle we could not only clamp all armour types
without the need for a reversible ring, but we
• The construction of the cable and/or could also achieve improved clamping of the
• The magnitude of the potential explosion armour with a lower installation torque. The
universal armour clamp is featured within
Barrier Glands Croclock (CR-***) and the Croclock family of
Glands featuring elastomeric Flameproof glands.
seals are often used where barrier glands are
required. Their specification and marking appear Seals
to confirm that the glands are suitable for use Compression seals, the original style of seal
in ATEX categories 2G (Zones 1 & 2), gas group where a rubber ring is compressed between 2
IIC and as passive components they have no gland parts causing the seal to seal on the cable.
temperature classification limitations. When the Displacement seals are similar to compression
installation code covering electrical installations seals in that the seal itself is a rubber ring.
in hazardous areas IEC 60079-14 is considered However, the seal is affected by one gland part
it is clear that a more detailed examination of pushing the seal down an internal taper. This
specific Flameproof applications must be made. allows for a more controlled application of the
“sealing force” onto the cable sheath.
The Cable Construction
The first questions that must be asked are with Diaphragm seals are affected simply by pushing
regard to the construction of the cable: the inner sheath of the cable through the seal.
• Is the cable substantially round and In our opinion this style of seal has two main
compact? drawbacks. First it is liable to rupture if installed
• Can the cable be deemed to be effectively incorrectly and second it cannot be removed
filled? without damage once installed.
• Is the cable effectively filled are the fillers
non-hygroscopic? Additional Features
If the answer to any of these questions is no, a We now, where applicable, certify our cable
barrier gland must be used. If the answer to all glands to protection concepts Ex d, Ex e, Ex ta and
3 questions is yes, the application must then be Ex nR. Our ATEX approved glands are Category
considered using the selection chart within IEC II 1D / II2G and where applicable II 3DG being
60079-14. suitable for Group II surface gases and Group I
dusts and are suitable for us in Zone 1, Zone 2,
The Cable Construction Zone 20, Zone 21 and Zone 22. All metallic glands
Determining whether the cable is effectively have an impact rating of at least 7Nm. Our
filled can often be difficult as cable companies cable glands featuring an elastomeric seal
do not declare their cable’s compliance and it is now maintain now maintain ingress protection
left to the specifying engineer to decide whether levels of IP66 and IP68 (50 metres) whilst our
or not an explosion within the enclosure could compound barrier glands maintain IP66 and IP68
be transmitted to the surrounding atmosphere (100 metres). Version for deluge protection are
through the cable. also available.
