To assure optimum gas monitoring efficiency and trouble-free operation, CD800/830 and CD802/832
Gas Alarm systems should be installed in accordance with the following procedures and specifications,
based on engineering design considerations and experience.
LOCATION OF DETECTORS
Detectors should be located at sites where the presence and concentrations of combustible gases must
be detected with respect to the following conditions (Figures 2-1 and 2-2):
Air currents: Detectors should be located where prevailing air currents contain the fullest possible
concentrations of escaping gas.
Relative weight of gas: Detectors should be located near the floor for heavier-than-air gases or
vapors from flammable liquid spills, and near the ceiling or roof to detect lighter-than-air gases
such as hydrogen and natural gas. Vapors from all liquids are heavier than air.
Dispersion of gas: Though detectors should not be far removed from any potential source of
escaping gas, liquids of low volatility especially demand location of the detector in the immediate
vicinity of the escaping vapor, since a slow rate of dispersion could result in falsely low sample
readings at short distances from the site.
Heat: Standard diffusion type detectors are designed to operate within a range of from -30° to
+200°F, but must be located away from areas outside this range. Special high-temperature
detectors are available, such as #0050-7005 (for temperatures to 340° F) or High Temperature
Probe #0023-7363 with #0023-7338 element, for temperatures to 600° F. Since diffusion sampling
is not feasible for detectors located remotely from the area to be monitored, the #0023-4017
remote sample drawing detector assembly is recommended for such applications. Practical
sampling line lengths of 75 to 100 feet are possible, using 1/4" OD tubing.
The #0023-4017 detector assembly must not be used to draw
flammable liquid vapors having flash points higher than the
expected ambient temperature from atmospheres at elevated
temperatures. On cooling to ambient temperatures, the vapors
of such samples may condense in the sample tubing before
reaching the reaction chamber. For high flash vapors,