Bacharach Halogen Monitor Instruction - 2.15 The P-Chk Function
Operation
Halogen Monitor
16
Instruction 3015-4584 Rev 9
R134A CALFACTOR
1.000
2.14 The Calibration Function
If greater than standard accuracy is desired, the factory’s default calibration factor of 1.000 may be
adjusted by performing the calibration procedure as described below, and then selecting the monitor’s
CAL
function to enter the new calibration factor.
IMPORTANT:
Changing the calibration factor will VOID the factory calibration. Typically,
the monitor will remain within the factory-calibrated accuracy indefinitely and no calibration
is required. Complex software algorithms adjust for temperature drift, IR source aging, and
pressure changes in order to keep the unit within factory accuracy specifications.
2.14.1 Calibration Procedure
The calibration factor is determined by sampling a known concentration of R-134A refrigerant gas. A
cylinder of a certified calibration gas must be used to ensure that the gas sample is a known
concentration at ambient conditions. A minimum sample size of 5 liters is required.
Calibration is best performed at or near full scale (1,000 ppm). It can, however, be done at any
concentration and ideally in the range where maximum accuracy is desired down to, but not below,
100 ppm.
The monitor should be operating for at least one hour prior to performing a calibration.
Prepare the monitor for sampling by using the
CAL
function to set the calibration factor to 1.000. Also,
use the
LOG INT
function to set the log interval to 1 minute.
With the monitor operating normally, connect the gas-sample bag directly to the gas-inlet port and allow
the monitor to sample the entire bag. When sampling is complete, view the logged ppm values using the
PPM LOG
function. If the bag was large enough for multiple samples, average the most stable ones. The
new calibration factor is computed by dividing the known gas concentration value by the measured value.
Typically this number will be between 0.95 and 1.05. Use the
CAL
function as described below to enter
the new calculated calibration factor
2.14.2 Adjusting Calibration Factor
From the
Data Display
screen, press any one of
the
Keypad
buttons to
display the first
Function Menu
screen. Next, use the
Keypad
buttons to
move the arrow (>) until it is next to the
CAL
function, and then press
ENTER
to display the
Calibration
screen.
With the
Calibration
screen displayed, use the
Keypad
buttons to enter the new calibration factor. Press
ENTER
to save this value.
2.15 The P-CHK Function
2.15.1 Overview
The
P-CHK
function (Pressure Check function) is useful to a service technician for troubleshooting a flow-
fault problem. The monitor will trigger a flow fault if the pressure drop from ambient is less than 0.2 psi
during a purge cycle, and 0.5 psi during a measurement cycle.
2.15.2 Keypad Functions
From the
Data Display
screen, press both
the
Keypad
Left
and
Right
buttons at the same time to
display the first
Function Menu
screen. Next, use the
Keypad
buttons to move the arrow (>) until it
points to the
P-CHK
function, and then press
ENTER
to display the
Pressure
screen.
The
Keypad Left
button toggles the purge valve open and closed. Note that an asterisk (*) appears when
the purge valve is
open
causing the monitor to draw air from the purge-air bag.