ENMET ISA-44-RALE-OD - Manual (Page 9)

ISA-44RALE-OD/ISA-44RAHE-OD/ISA-44E-OD ENMET Corporation
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1.4 Special Characteristics
Special enclosures and circuitry protect the instrument from becoming a potential source of ignition. The ISA-44RALE-
OD is housed in an explosion proof enclosure for Class I, Group C, D and Class II, Groups E, F, and G atmospheres.
This means that when the ISA-44RALE-OD is used properly in one of these environments, if combustible gas from the
area is ignited inside the control unit or MOS sensor assembly, the explosion would be completely contained within either
unit. In addition, an intrinsic safety barrier protects the oxygen cell and circuit against possible ignition. Acting as a fuse,
this barrier prevents a surge of electrical power from reaching the oxygen cell, so the cell will not explode or burn. A
surge of electricity will break the circuit connection inside the barrier, so the barrier must be replaced if this should occur.
1.5 Calibration Explained for the ISA-44E-OD
The oxygen portion of this unit is the same as for the ISA-44RALE-OD. The gas portion of this unit will change
depending on the end users criteria. As in the ISA-44RALE-OD the alarm points are preset at the factory and calibration
information can be found labeled on the face plate of the unit.
C AUTION : If the covers of either the control unit or the MOS sensor enclosure are removed, the enclosures are no longer
explosion proof.