CM4 Four-Point Continuous Monitor
CM4 Technical Manual
1-3
1.2 Sampling and Monitoring System
The system draws sample flow simultaneously from all four points.
Two different types of sample movement are:
• Transport flow: high-velocity, large-volume air movement
through the lines
• Sample flow: air admitted to the Chemcassette
®
detection
system
The high speed of transport flow allows rapid monitoring and response
time when using long lines from monitoring points to the CM4. A small
portion of the transport flow is analyzed to determine concentration
levels.
NOTE:
On newer style CM4 (S/N XXX-5000 and greater) and all CM4-P
models, the flow controls (item 6) are located on the lower left
of the front panel. An ambient air filter (item 10) is located on
the lower right.
The flow system includes:
Flow connections (Manifolds) Orifice
Pump
Valves
Filters
Transducers
1.2.1 Flow Connections
Flow connections consist of quick-connect ports on the back of the
CM4. There are four inlets, one for each monitored point, and an
exhaust outlet.
1.2.2 Pump
The pump provides a vacuum source for transport and sample flow
during monitoring.
1.2.3 Filters
Filters protect the internal precision orifice from dust particles. Filters
are located in a removable filter block on the top of the instrument.
See
for information about filter replacement.
Figure 1-2: CM4 Components and Controls
LEGEND
1. Tape load lever
2. 20-character display
3. Alarm relays
4. Detectors and electronics
5. Status and alarm LEDs
6. Flow controls
7. Keypad
8. Filter block
9. Carrier
10. Air filter
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6
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Table Mount
Wall Mount
9
6
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