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What Is Difference Between Single Compression And Double Compression?

Answer»
  • Double compression glands provide extra SUPPORT to the heavy armored cables entering or exiting the panel while single compression glands are used for light armored cables.
  • Normal Cable Gland is also called Single Compression Cable Gland. As the name suggests, while you tighten the gland, the grip or compression is effected only at one p [lace (i.e.) at the cable armour only. There is scope for moisture and corrosive vapour to enter the gland and thus into the cable.
  • Whereas in Double-Compression Gland, the compression happens both at the cable armour as well as at the INNER sheath. This is sort of two sealing. Hence, chances of moisture or vapour entry are minimized. Hence these glands are also known as Weather-proof cable glands or Flame-proof cable glands.
  • The basic difference between single and double compression is in Single comp there no cone and cone ring.
  • The mechanical support for the cable is only Neoprene rubber SEAL, When you tighten the cable.
  • In double camp gland the mechanical support to the cable only cone and cone ring. When we are doing glanding the cable armor sits on the cone and cone ring ACT as a lock for armor.
  • Single compression and double compression glands are used on the basis of area classification. Those who are affiliated with oil and gas sector they will easily understand about area classification.
  • In zone 0 where the presence of hydrocarbon is obvious (IIC) double compression gland is used because the flame path in case of double compression gland is much more than in case of single compression gland.
  • The logic behind this is that if there is any explosion inside the terminal box of the motor no flame should be able to COME out through the cable gland in order to prevent fire hazards but where there is no presence of hydrocarbons i.e. no danger of fire hazards (IIA/ IIB) single compression glands are used.
  • It has nothing to do with mechanical strength. Even in case of lighting fixtures used in IIC zone double compression glands are used.


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