8 • 35-3001A-10 Oxygen/Carbon Monoxide Sample-Draw Detector
External Components
This section describes the sample-draw detector’s external components.
Housing
The sample-draw detector’s fiberglass housing is weather- and corrosion-resistant. It is suitable for
installation where general purpose equipment is in use.
The housing door is hinged on the left side and is secured by two latches on the right side. The
flowmeter and status LEDs are visible through a window in the housing door.
Four mounting feet are attached to the back of the housing (one at each corner). Use the mounting feet
to install the housing to a vertical surface.
Sample Fittings
The sample fittings are located on the left side of the bottom of the housing. The inlet fitting is near the
front of the housing and the exhaust fitting is near the back of the housing. The sample fittings accept
1/4 in. rigid tubing. See page 13 for instructions to connect tubing to the sample fittings.
Particle Filter
A particle filter with a tubing stub on one end is shipped with the instrument but it is not factory
installed. If the particle filter is installed directly to the inlet fitting, the tubing stub must be used. If the
particle filter is installed somewhere else, like at the end of the inlet line, the tubing stub can be used or
removed.
Conduit Hub
One 3/4” conduit hub is located on the right side of the bottom of the housing. It is used for routing
wiring into the housing by using conduit or an appropriate cable bushing.
Internal Components
This section describes the sample-draw detector’s internal components (see Figure 1). Figure 2
illustrates how the gas sample moves through the flow system.
Figure 2: Flow Diagram
Restrictor
Oxygen
Sensor
Pump
CO
Sensor
Flowmeter
Flow Baffle
Particle Filter
Sensor Flow
Control Valve
Exhaust
Flowmeter PCB
Pressure Switch
Hydrophobic Filter
Inlet
