Installation
3.6
Maintaining the X/P Integrity
The Model S104 is rated explosion proof for
Class I, Division 1, Group B, C & D hazard-
ous locations. Some of the factors that influ-
ence the explosion proof integrity of the
Model S104 Housing:
l
Strength of the enclosure material
l
Thickness of the enclosure walls
l
Flame path between the housing and
cover
l
Flame path of threaded joints
The acceptable limits for explosion proof
housings that are used in Class I hazardous lo-
cations are defined in CSA Standard C22.2
No.30-M1986.
Anytime the cover of the smart sensor hous-
ing is removed or the cover bolts are loos-
ened, the flame path between the lid and the
housing is effected. If power is left on before
loosening the cover bolts on the Model S104,
it will be necessary to de-classify the area.
When replacing the cover, the gap between
the lid and the housing should be less than
.0015 inch (.038 mm). This can be verified
by tightening the cover bolts to a torque set-
ting of 50 inch-pounds or by using a feeler
gauge to ensure the gap between the cover
and the housing is less than .0015 inch (.038
mm).
There are four entry holes in the Model S104
housing.
These holes are dedicated for the
sensor, the calibration switch and conduit.
Each hole is tapped for 3/4 NPT threads. If a
particular entry hole is not used it must be
plugged during operation in the field.
The
factory installs plugs for two of the entry
holes.
A plastic red cap plug is placed into the re-
maining hole and must be removed before
conduit can be attached to the housing.
An S104 without a display will have the fol-
lowing items placed in the remaining three
entry holes:
l
A sensor, if present (if not, a plastic
red cap-plug)
l
A calibration switch
l
An aluminum housing plug
An S104 with a display will have the follow-
ing items placed in the remaining three entry
holes:
l
A sensor, if present (if not, a plastic
red cap-plug)
l
Two aluminum housing plugs
The sensor, calibration switch and aluminum
housing plugs have seven threads.
Each of
these components is screwed into the housing
using five to seven turns. If it becomes neces-
sary to replace one of these components, the
user must use five to seven turns to ensure the
explosion proof integrity of the housing.
10
GENERAL MONITORS
Model S104
