AQ EXPERT Instruction & Operations Manual
Version 1.13
Page 49 of 63
To replace the filters, remove the top section of the instrument case (see section B
below for more details on how to remove top section of the instrument) and disconnect
the two pieces of flexible tubing that hold the respective filters in place. If you are
replacing the disk filter,
make sure that the filter’s lettering is facing the front face of the
instrument.
B. Sensor Replacement
This should be an infrequent operation, since the sensors have a typical life of a few
years.
If you receive an error message for one of the sensors during instrument operation you
may have to replace the sensor. Please contact E Instruments for replacement
sensors. The user can send the unit back to the factory for sensor installation and re-
calibration of the instrument or the sensors can be replaced in the field. The
replacement sensors will be supplied with installation instructions.
To access the sensor compartment you must remove the top section of the instrument
case. The top section of the monitor case
is held to the bottom section by a total of four
retaining screws. With both hands, slide off the vent covers on each side. Use a Philips
screwdriver to remove both pairs of retaining screws (one pair on each side of the
case). It is best to remove the bottom pair of screws first. Carefully lift the top of the
instrument case together with the attached aluminum mounting shielding plate
especially since the top & bottom cases pieces are connected with cables/wires. When
the plastic case is open, be careful when near the main board because some of the
resistors on the board can get significantly hot. The location of the gas sensors on the
manifold is shown in the figure in Chapter 5.
To replace a sensor, locate its correct position on the manifold. Carefully lift the small
PC board that is mounted on top of the sensor. Grab the sensor with your fingers and lift
it twisting it out of its bayonet fitting.
Take a new sensor. Remove any springs that may be shorting the sensor pins. Install it
on its mount and connect the small PC board on top of it.
Replace the top section of the case and secure it with the four screws.
Wait 30 minutes before zeroing the monitor:
NOTE: You must always span calibrate the instrument every time
you replace a sensor.
NOTE: CO
2
should ALWAYS be Calibrated or Zeroed with a Cylinder of ZERO
AIR. Do Not Use AQ CAL-ZF for CO
2
sensor calibration.
