CM4 Four-Point Continuous Monitor
CM4 Technical Manual
1-5
1.3.3 Chemcassette
®
Detection System
1
2
3
4
5
FLOW
6
7
Figure 1-4: Chemcassette Detection System
Legend
1
Chemcassette
®
tape
5
Sample inlet
2
Electronics
6
Pressure transducer port
3
LED light source
7
Sample outlet
4
Detector
1. The sample enters the inlet (5) and passes through the
Chemcassette
®
tape (1) to the sample outlet (7).
2. Target gas in the sample flow reacts with the Chemcassette
®
tape (1) and produces a stain density proportional to the gas
concentration.
3. An LED (3) in the CM4 detector head illuminates the sample
stain. The detector (4) optically measures the stain.
4. The CM4 CPU interprets the stain, then reports a precise
concentration level in parts-per-million (ppm) or parts-per-
billion (ppb).
1.3.4 Measuring Gases
Chemcassettes
®
are available for measurement of gases as well as
families of gases. Gases and families the CM4 detects include (See
for more information):
Ammonia (NH
3
)
Hydrogen Iodide (HI)
Arsine (AsH
3
)
Hydrogen Selenide (H
2
Se)
Boron Trifluoride (BF
3
)
Hydrogen Sulfide (H
2
S)
Chlorine (Cl
2
)
Hydrazine (N
2
H
4
)
Chlorine Dioxide (ClO
2
)
Monomethyl Hydrazine (MMH)
Diborane (B
2
H
6
)
Nitrogen Dioxide (NO
2
)
Dimethyl Amine (DMA)
Phosgene (COCl
2
)
Dimethyl Hydrazine (UDMH) Phosphine (PH
3
)
Fluorine (F
2
)
Silane (SiH
4
)
Germane (GeH
4
)
Sulfur Dioxide (SO
2
)
Hydrogen Bromide (HBr) Tert-Butyl Arsine (TBA)
Hydrogen Chloride (HCl) Tert-Butyl Phosphine (TBP)
Hydrogen Cyanide (HCN) Triethyl Amine (TEA)
Hydrogen Fluoride (HF)
Tetrakis(dimethylamino) titanium
(TDMAT)
The pyrolyzer Model CM4-P is specially designed to detect special gases
using high temperature to “crack” those gases into Chemcassette
®
detectable gases. Current CM4-P detectable gases are:
Nitrogen Trifluoride (NF
3
)
Methyl Fluoride (CH
3
F)
The Model CM4-P is not designed to accept other calibrations, and
cannot be converted.
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