RKI Instruments 65-2497RK - Manual (Page 7)

65-2494RK/65-2497RK Oxygen Detector • 3
Detector Housing Body
The detector housing body protects the electronic components within the housing. Use the
mounting threads at the top of the housing to screw the oxygen detector into a 3/4” NPT
hub. Two wires extend from the top of the detector housing body. Use these wires to
connect the detector to a controller. One of the wires is white and one of the wires is green.
The housing body includes two sockets installed on a circuit board. These sockets accept
the plug-in sensor’s two pins to provide an electrical connection for the sensor. The circuit
board with the sockets conditions the sensor’s signal before the signal reaches the
controller.
Housing Cap & Cap Gasket
The housing cap screws onto the detector housing. It retains the plug-in sensor and
protects it from damage. A foam gasket inside the housing cap seals against the face of the
sensor when the cap is screwed on the housing body. A hydrophobic membrane on the
outside of the cap face keeps water and particulates away from the sensor face behind the
cap. Unscrew the detector cap to access the plug-in sensor for maintenance or
replacement. A cap gasket seals the interface between the housing and cap.
Plug-in Sensor
The plug-in sensor is secured in the detector assembly by the housing cap. Through a
series of chemical and electrical reactions, the sensor produces an electrical output that
corresponds to the detection range of the detector. The sensing element used is a capillary
type that is not susceptible to output changes with changes in atmospheric pressure.
Junction Box
Use the junction box to install the oxygen detector at a mounting site that is remote from a
controller and to protect the detector wiring connections. Two conduit hubs allow you to
mount the detector to the junction box and connect the wiring from the detector to a
controller. Three spacers installed on the back of the junction box control the distance of
the junction box from a mounting surface and ensure that there is enough room to install a
calibration cup on the detector during calibration. A terminal block within the junction
box facilitates the wiring connections. A cover on the front of the junction box allows
access to the interior of the junction box.
Installation
This section describes procedures to mount the oxygen detector in the monitoring
environment and wire the detector to a controller.
Mounting the Oxygen Detector
NOTE: If you are installing a 65-2494RK, it does not include a junction box and is usually
factory installed in one of a controller’s conduit hubs or may be field installed
using the 3/4” NPT threads on the end with the wires. The 65-2497RK includes a
junction box as shown in Figure 3 below.
1. Select a mounting site that is representative of the monitoring environment. Consider
the following when you select the mounting site.
• Select a site where the detector is not likely to be bumped or disturbed. Make sure
there is sufficient room to perform start-up, maintenance, and calibration
procedures.