35-3010A-11 Sample-Draw Detector • 7
Flow System
The sample draw detector’s flow system consists of the INLET fitting, hydrophobic filter,
charcoal filter, pump, flowmeter, bypass valve, status lights, pressure switch, flow block,
and EXHAUST fitting (see Figure 1). Figure 2 illustrates how the gas sample moves
through the flow system.
Figure 2: Sample Draw Detector Flow Diagram
INLET Fitting
The INLET fitting on the bottom of the housing allows the gas sample to enter the sample
draw detector. The INLET fitting accepts 1/4 in. rigid tubing. See “Installation” on
page 13 for instructions to connect tubing to the INLET fitting.
Hydrophobic Filter
The hydrophobic filter is to the left of the main circuit board. It is held in place by a metal
clip. It prevents water and other liquids from contaminating the flow system. Replace the
filter when it appears dirty, discolored, or clogged. If a liquid other than water is drawn
into the filter, replace the filter as soon as possible.
CO2
Charcoal
Filter
Pressure Switch
H2S
Oxygen
Dummy
Plug
Flow meter
Bypass
Valve
Flow Block
CO
Dummy
Plug
LEL
Pump
Exhaust
Inlet
Hydrophobic
Filter
