Carbon Monoxide Alarm User Manual

Page 20
(Pressing the MODE button at any time cancels the
calibration mode, and returns the instrument to the gas
reading screen.)
(7) Slip the sample draw / calibration adapter over the
end of the instrument.
(Make sure to use the adaptor supplied with the hand
aspirated sample draw assembly. Do not use the
battery operated sample draw pump for this
purpose.)
(8) Attach the regulator to the calibration gas cylinder.
Make sure the regulator, cylinder seating surfaces,
and threads are clean and dry.
Make sure the regulator, cylinder
seating surfaces and threads are clean and dry
before attaching the regulator to the cylinder of gas.
Introduction of contaminants through the regulator
fittings may alter or degrade the concentration of the
gas contained in the cylinder and may lead to
inaccurate and potentially dangerous gas readings.
(9) Connect the flexible hose between the calibration
adapter and the regulator on the calibration gas
cylinder.
(10) Open the calibration gas regulator valve fully to
obtain a flow of approximately 1.0 liters per minute.
(11) When the readings stabilize, use the "+" and "-" keys
to raise or lower the readings to match the
concentration printed on the calibration cylinder
label.
(12) When the span calibration for a particular sensor is
completed, advance to the next channel by pushing
the "Cal" button.
(13) Make sure the correct cylinder of gas is attached
before attempting to adjust the span! If the
concentration of gas reaching the sensor is too low to
allow the instrument to be adjusted, or if the wrong
type of gas is applied to the sensor being adjusted, a
screen will be displayed indicating that the span gas
concentration is too low. Verify that the flow rate of
the regulator is 1.0 lpm. Replace the cylinder, or
choose the correct sensor, and continue.
(14) When span calibration has been completed for all
channels, press and hold the "Cal" button down until
the information screen indicates that calibration is
complete. The PhD
2
will then turn itself off.
CAUTION: The “Cal” button must be held down until
the screen indicates that span calibration has been
successfully completed.
If the button is released before this message is displayed,
span values will not be updated, and remain unchanged
from the last time a span calibration was successfully
completed.
3.4.1 Calibration procedures for sulfur
dioxide, ammonia, chlorine, hydrogen
cyanide, and hydrogen chloride
“corrosive gas” sensors.
Highly reactive or "corrosive" gases such as sulfur
dioxide, ammonia, chlorine, hydrogen cyanide, and
hydrogen chloride tend to react quickly with or be
absorbed by other substances. These reactions can
occur so quickly that there may not be adequate time for
the gases to diffuse through the moisture barrier in the
standard PhD
2
sensor compartment cover before they
are gone.
The standard sensor
compartment cover (which includes a moisture
barrier) may not be used as long as a corrosive gas
sensor is installed. When the sensors installed in
your PhD
2
include a corrosive gas sensor, a special
sensor compartment cover (part number 35-692)
must also be installed.
Note: The sensor compartment cover used when a
sulfur dioxide, chlorine, ammonia, hydrogen cyanide,
hydrogen chloride, or TOX 1 sensor is installed does
not include a moisture barrier filter. Avoid direct
exposure to liquids to reduce the chance for damage
due to leakage.
Sulfur dioxide, ammonia, chlorine, hydrogen cyanide, and
hydrogen chloride calibration kits include a special
Teflon

calibration adaptor, and a length of FEP (fluoro-
polymer) lined tubing used to connect the adaptor to the
cylinder of calibration gas.
The standard sample draw / calibration adapter used
during non-corrosive span adjustment procedures flows
gas to all sensors simultaneously. The Teflon

calibration adaptor is a small white cylindrical cup
designed to flow gas to a single sensor at a time.
3.4.1.1 Corrosive gas sensor functional
(bump) test
It is possible to do a functional (bump) test to verify the
accuracy of a corrosive gas sensor. The sensor
compartment cover may be left in place for this
procedure.
(1) Attach the regulator to the calibration gas cylinder.
Make sure the regulator, cylinder-seating surfaces,
and threads are clean and dry. It is best to leave the
regulator “open” and flowing gas when attaching it to