27
8.
After calibration, the detector will show
"CAL"
and the instrument will beep briefly.
Remove the probe from the gas outlet. Replace the black #4-40 screw and the
instrument is ready for use.
Note:
During calibration, the selector switch remains in the TRACK GAS position.
After calibration is complete and
"CAL"
is displayed, the selector switch must be
placed at the OFF position to return the detector to a normal operation mode.
Note:
Error codes during calibration are the same as those during SCAL calibration (see
Sect.11C).
CAUTION:
Automatic calibration presupposes and depends on using Bascom-Turner's
calibration gas (Part No. MC-620). Do not use a gas of a different composition
for automatic calibration.
E.
Adjustment of the Block Limit of the Pump
If a
"bloc"
signal is not displayed when the air intake to the instrument is directly
blocked, the problem may be corrected by adjusting the block limit used to detect a block.
1.
Observe the Pump Current in Normal Operation and When Blocked
To adjust the
"bloc"
limit, first enter the set up mode, described at the beginning of this
Section 11 (press RESET and the push-button simultaneously while switching the front panel
switch to AUTO ZERO), and note the reading on the display following
"Pu"
(see Table 2). It
represents in arbitrary units the current to the pump. When the probe is blocked, a reading with a
decimal point, for example 350.0, should be displayed.
If a decimal point is not displayed, the block limit may be too high. If required, adjust the
block limit, as described below, to some lower value. The block limit should not be set to a
value less than one and a half times (1.5x) the value observed when the probe is
not
blocked.
Otherwise, a
"bloc"
signal may appear in normal operation. If this margin to normal operation
cannot be maintained, the pump must be re-adjusted mechanically.
2.
Adjust the Block Limit
To adjust the block limit to some lower value, for example, 3000 place the front panel
switch in a position other than AUTO ZERO and then back to AUTO ZERO and press the push-
button. The instrument will be in the alarm setting and option selection mode (Section 10).
Press the push-button until
"Pu"
appears on the display followed by 3500. Press RESET to show
"On"
, then press the push-button to show 3500 with the underlined digit flashing. Press the
push-button again to advance the flashing digit to the second position. Now press RESET to
advance this digit to 0 and then press the push-button three more times until Pu appears followed
by 3000. Exit by placing the front panel switch at some position other than AUTO ZERO.
