Air Sampling System - Honeywell ACM 150 Manual To Installation, Operation, And Maintenance

ACM 150

Air sampling system

ACM 150 flow cycles
The ACM 150 monitor is designed to move air samples from one area to the next
as quickly and efficiently as possible, while assuring that each sample is fresh and
representative of the air at the sampled area when it is analyzed. The Cycle Valves
are shown in Figure
The ACM 150 monitor does this by sampling each area in four steps or flow cycles
with the following valves opened:
• Evacuate: S1 and S6
• Surge: S2 and S6
• Fill: S2
• Analyze: S1
Table 1 shows the timing range for each flow cycle and the pressure or range of
pressure in the gas cell during the cycle.
Evacuation cycle: The ACM 150 monitor starts each sampling cycle by switching
the valves so that the Gas Cell Venturi Pump draws a vacuum on the gas cell. The
inlet valve to the gas cell is shut off. This creates a large vacuum in the gas cell and
efficiently removes the sample gas from the area just analyzed. While the gas cell is
evacuated, the Boost Pump draws the sample air from the next area to be scanned,
and its flow is diverted to bypass.
Surge cycle: The Gas Cell Venturi Pump continues to draw on the gas cell, but now
the inlet valve to the gas cell is opened. This allows a surge of new sample from the
Boost Pump into the gas cell. This replaces sample from the last area scanned with
fresh sample from the current area.
Fill cycle: The valve to the Gas Cell Venturi Pump is shut and the gas cell fills with
the new air sample until it reaches atmospheric pressure. The gas cell is allowed
to equilibrate to atmospheric pressure before analysis begins. The calibrations for
the measured components, used to develop the analytical methods, are all done at
atmospheric pressure. If the analysis were not done at atmospheric pressure, the
results would not be accurate.
Analyze cycle: The valves on the inlet and outlet of the gas cell are closed. The FTIR
analyzer collects the infrared spectrum of the current air sample and sends it to
the computer, where the data is extracted from the spectrum and reported as gas
concentrations.
This sequence is automatically repeated for each area sampled on a continuous
24 hours cycle. It is only interrupted by Background scans or when the ACM 150
monitor is no longer in automatic mode.
Bypass and order of scan
When the air sample from an area is being analyzed by the ACM 150 monitor, the
corresponding sample area number and name are displayed in the status bar on the
touchscreen.
As soon as the Analyze cycle begins, the sample valve for the next area in the
scan sequence opens. The Boost Pump draws the sample from that next area and
bypasses it to exhaust (S1 opens). The purpose is to ensure that the internal tubing
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