Guildline Autosal 8400B User manual

TECHNICAL MANUAL
FOR
MODEL 8400B
“AUTOSAL”
NOTICE
The contents and information contained in this manual are proprietary to
Guildline Instruments Limited. They are to be used only as a guide to the
operation and maintenance of the equipment with which this manual was
issued, and may not be duplicated or transmitted by any means, either in
whole or in part, without the written permission of Guildline Instruments
Limited.
TM8400B-L-00
1 November 2004

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TABLE OF CONTENTS
1. INTRODUCTION...................................................................................................1-1
1.1. SCOPE................................................................................................................................................... 1-1
1.2. UNIT DESCRIPTION ......................................................................................................................... 1-1
1.2.1. APPLICATION................................................................................................................................. 1-1
1.2.2. PHYSICAL LAYOUT ...................................................................................................................... 1-1
1.3. CARE AND HANDLING.................................................................................................................... 1-1
1.3.1. USAGE.............................................................................................................................................. 1-1
1.3.2. CARRYING/TRANSPORTATION/STORAGE .............................................................................. 1-1
1.3.3. MAINTENANCE REQUIREMENTS .............................................................................................. 1-2
1.3.4. RECEIVING AND INSPECTION.................................................................................................... 1-2
2. SPECIFICATIONS................................................................................................2-1
2.1. GENERAL SPECIFICATIONS ......................................................................................................... 2-1
2.2. PERFORMANCE ................................................................................................................................ 2-2
3. OPERATING DATA..............................................................................................3-1
3.1. MEASUREMENT THEORY.............................................................................................................. 3-1
3.2. SAMPLE WATER FLOW ARRANGEMENT................................................................................. 3-3
3.3. BATH TEMPERATURE CONTROL................................................................................................ 3-4
3.4. SAMPLE FLOW RATE...................................................................................................................... 3-4
3.5. CONDUCTIVITY MEASURING CIRCUIT.................................................................................... 3-4
3.6. DISPLAY CIRCUITRY ...................................................................................................................... 3-6
4. CONTROLS AND INDICATORS..........................................................................4-1
4.1. GENERAL............................................................................................................................................ 4-1
4.2. CONTROLS.......................................................................................................................................... 4-1
4.3. INDICATORS ...................................................................................................................................... 4-2
5. INSTALLATION....................................................................................................5-1
5.1. GENERAL............................................................................................................................................ 5-1

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5.2. PROCEDURE....................................................................................................................................... 5-1
5.2.1. PRELIMINARY CHECK ................................................................................................................. 5-1
5.2.2. TEMPERATURE BATH FILLING.................................................................................................. 5-2
5.2.3. PRELIMINARY FUNCTION CHECK ............................................................................................ 5-3
5.2.4. BATH TEMPERATURE CONTROL CHECK................................................................................ 5-3
5.2.5. CONDUCTIVITY CELL CHECK.................................................................................................... 5-4
6. OPERATING INSTRUCTIONS.............................................................................6-1
6.1. GENERAL............................................................................................................................................ 6-1
6.2. OPERATING SEQUENCE................................................................................................................. 6-1
6.2.1. CHECKING ZERO REFERENCE ................................................................................................... 6-1
6.2.2. STANDARDIZATION PROCEDURE............................................................................................. 6-2
6.2.3. SAMPLE MEASURING PROCEDURE.......................................................................................... 6-3
6.3. CONVERTING INSTRUMENT READING TO SALINITY.......................................................... 6-5
6.4. STANDARD OPERATING PRACTICES......................................................................................... 6-6
6.5. MEASURING FOR OPTIMAL ACCURACY.................................................................................. 6-6
6.5.1. INSTRUMENT ACCURACY .......................................................................................................... 6-6
6.5.2. PROCEDURAL REFINEMENTS .................................................................................................... 6-6
6.6. SAMPLE HANDLING FOR OPTIMAL ACCURACY................................................................... 6-7
6.6.1. METHOD TO REMOVE SAMPLE BOTTLE AND LEAVE CELL FULL.................................... 6-7
6.6.2. METHOD TO REMOVE WATER FROM PICKUP TUBE PRIOR TO MEASURING NEW
SAMPLE.......................................................................................................................................................... 6-8
7. INSTALLATION AND OPERATING INSTRUCTIONS FOR OPTIONAL BCD
OUTPUT ......................................................................................................................7-1
7.1. GENERAL............................................................................................................................................ 7-1
7.2. BCD CONNECTOR PIN CODE ........................................................................................................ 7-1
7.3. OPERATING PROCEDURE.............................................................................................................. 7-1
8. GENERAL TECHNICAL INFORMATION.............................................................8-1
8.1. INSTRUMENT COMPONENT LOCATION................................................................................... 8-1
8.1.1. CABINET.......................................................................................................................................... 8-1
8.1.2. CHASSIS........................................................................................................................................... 8-1
9. THEORY OF OPERATION...................................................................................9-1
9.1. GENERAL............................................................................................................................................ 9-1
9.2. POWER SUPPLY ................................................................................................................................ 9-1

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9.3. TEMPERATURE CONTROL CIRCUIT.......................................................................................... 9-1
9.4. CONDUCTIVITY MEASURING CIRCUIT.................................................................................... 9-2
9.5. METER ASSEMBLY .......................................................................................................................... 9-3
9.5.1. METER CIRCUIT............................................................................................................................. 9-3
9.5.2. DISPLAY CIRCUIT ......................................................................................................................... 9-3
10. MAINTENANCE..............................................................................................10-1
10.1. INTRODUCTION.............................................................................................................................. 10-1
10.2. GENERAL INSPECTION ................................................................................................................ 10-1
10.3. GENERAL CLEANING.................................................................................................................... 10-1
10.4. OPENING THE CABINET............................................................................................................... 10-1
10.5. BATH TEMPERATURE VERIFICATION TEST......................................................................... 10-2
10.6. DISPLAY METER TEST.................................................................................................................. 10-2
10.7. HEATER LAMP REPLACEMENT ................................................................................................ 10-3
10.8. CONDUCTIVITY CELL REMOVAL............................................................................................. 10-3
10.9. PUMP SERVICING........................................................................................................................... 10-4
10.9.1. SERVICE INSTRUCTIONS...................................................................................................... 10-4
11. SERVICING AND CALIBRATION ..................................................................11-1
11.1. GENERAL.......................................................................................................................................... 11-1
11.2. MAINTENANCE SCHEDULE ........................................................................................................ 11-1
11.3. SERVICE NOTES.............................................................................................................................. 11-1
11.3.1. CLEANING FLUSHING MANIFOLD/TUBES........................................................................ 11-1
11.3.2. CHECKING THERMOELECTRIC COOLING UNIT.............................................................. 11-3
11.3.3. CHECKING IMPELLER ........................................................................................................... 11-3
11.3.4. CHECKING HEATER LAMPS................................................................................................. 11-3
11.3.5. REMOVING TOP PANEL......................................................................................................... 11-3
11.3.6. REMOVING TANK................................................................................................................... 11-4
11.4. AUTOSAL CALIBRATION............................................................................................................. 11-4
11.4.1. POWER SUPPLY CALIBRATION........................................................................................... 11-5
11.4.2. CONDUCTIVITY PCB CHECK ............................................................................................... 11-6
11.4.3. METER CALIBRATION........................................................................................................... 11-7
11.4.4. MATCHING AND BALANCING............................................................................................. 11-7
12. TROUBLESHOOTING....................................................................................12-1

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12.1. GENERAL.......................................................................................................................................... 12-1
13. RECOMMENDED SPARE PARTS.................................................................13-1
13.1. STANDARD SPARE PARTS............................................................................................................ 13-1
13.2. MAINTENANCE KIT....................................................................................................................... 13-1
13.3. PUMP MOTOR REPLACEMENT KIT.......................................................................................... 13-1
14. PARTS LISTS.................................................................................................14-1
15. DRAWINGS.....................................................................................................15-1

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TABLE OF FIGURES
FIGURE 3.1: LABORATORY SALINOMETER FLOW DIAGRAM................................................................... 3-2
FIGURE 3.2: CONDUCTIVITY MEASURING CIRCUIT..................................................................................... 3-5
FIGURE 4.1: FRONT PANEL................................................................................................................................. 4-3
FIGURE 7.1: CONNECTOR PINOUTS ................................................................................................................. 7-2
FIGURE 8.1: CHASSIS BACK............................................................................................................................... 8-2
FIGURE 8.2: FRONT PANEL................................................................................................................................. 8-3
FIGURE 8.3: TOP PANEL...................................................................................................................................... 8-4
FIGURE 9.1: TIMING DIAGRAM......................................................................................................................... 9-4
FIGURE 11.1: CONDUCTIVITY CELL SIMULATOR ....................................................................................... 11-9

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LIST OF TABLES
2-1: GENERAL SPECIFICATIONS ......................................................................................................... 2-1
2-2: PERFORMANCE ............................................................................................................................... 2-2
7-1: BCD CONNECTOR PIN CODING ................................................................................................... 7-2
11-1: MAINTENANCE SCHEDULE...................................................................................................... 11-2
11-2: OPERATING CHECKS SCHEDULE............................................................................................ 11-2
11-3: SIMULATION RESISTANCES................................................................................................... 11-12
12-1: TROUBLESHOOTING GUIDE..................................................................................................... 12-5

Section 1
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1-1
1. INTRODUCTION
1.1. SCOPE
This manual contains technical specifications, detailed description and maintenance information,
parts lists, and diagrams for the Guildline Instruments 8400B AUTOSAL "Laboratory
Salinometer".
1.2. UNIT DESCRIPTION
1.2.1. APPLICATION
The instrument is semi-portable, semi-automatic, and is used in the land based or sea-
borne laboratory to determine salinity levels in saline samples by measuring the
equivalent conductivity ratio to a standard seawater sample.
1.2.2. PHYSICAL LAYOUT
The instrument is enclosed in an aluminum cabinet measuring 68 cm high, 53 cm wide
and 55 cm deep; maximum total weight is approximately 70 kg. The cabinet incorporates
a flushmounted handle on each side for easy carrying and is designed for bench
mounting. The instrument chassis is held in place in the cabinet on four track slides for
easy withdrawal from the front by removing four polished binder head screws.
Removing the three left-hand screws allows the front panel to hinge out. All primary
controls, indicators, and the adjustable sample bottle holder, cell inspection window and
external tubing connections are located on the front panel. Power input, 120/240 volt
switching and the BCD OUTPUT connector are located on the rear panel.
1.3. CARE AND HANDLING
1.3.1. USAGE
Although this instrument is designed for high precision measurement it is quite rugged.
It requires only reasonable care and good maintenance practices to ensure optimum
performance. It can withstand continuous operation and if required, long periods
between operations.
1.3.2. CARRYING/TRANSPORTATION/STORAGE
The handles provided on the sides of the cabinet provide the easiest, safest means of
lifting the instrument. Use the valves provided to drain the internal fluids and so reduce
weight, prevent possible leakage during transportation, and to prevent damage if
subjected to below freezing temperatures. A tank drain plug is provided with the unit for
eliminating drips from the nipple during transportation.

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1.3.3. MAINTENANCE REQUIREMENTS
Use the maintenance schedule (Section 10) as a guide for planning the implementation of
the recommended, in-service maintenance.
1.3.4. RECEIVING AND INSPECTION
This instrument is thoroughly tested and inspected before packing and shipping. As soon
as possible after receipt, inspect the instrument for external damage, ensure that all items
in the packing list are present, and complete the installation checks. Refer to the
warranty card at the front of this manual for further instruction if any damage or
deficiency is found.

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2-1
2. SPECIFICATIONS
2.1. GENERAL SPECIFICATIONS
MODEL 8400B
General Specifications
Operating Temperature
14 to 35
°C
57 to 95
°F
Storage Temperature
-20 to +60
°C
-4 to +140
°F
Operating Humidity (non-condensing)
20 to 50
% RH
Storage Humidity (non-condensing)
15 to 80
% RH
Power Requirements
400
W
Voltage Requirements
115/230 ±10%
VAC
Line Frequency
50/60
Hz
Dimensions (Nominal)
68 high X 53 wide X 55 deep
cm
27 high X 21 wide X 22 deep
in
Weight Bath empty
52
kg
115
lb
Bath full
70
kg
150
lb
Shipping
88
kg
193
lb
Outputs:
TTL compatible BCD
- numerical display readings,
- thumbwheel switch bottle logger
Water Bath Volume
16.8
litres
4.4
gal US
Table 2-1: General Specifications

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2-2
2.2. PERFORMANCE
Measurement Range:
0.005 to 42
PSU
24 Hour Accuracy:
better than ±0.002
(In the range of 2 –38)
PSU
over 24 hours without
restandardization
10 Minute Stability:
better than ±0.0006
(In the range of 2 –38)
PSU
over 10 minutes
equivalent to ±0.00003
units of display
Maximum Resolution:
better than ±0.0002
PSU
at 35 PSU
Sample Volume:
100
ml
including maximum
flushing volume
50
ml
for 3 PSU difference
between samples
Water Bath
Temperature:
18 to 33
°C
Selectable in 3°C steps
Accuracy
±0.02
°C
selected temperature
should be within
[ambient + 4] °C and
[ambient - 2] °C
Stability
±0.001
°C/day
Scale Suppression: Linear scale of conductivity ratio having 22 steps from 0 to 2.2 where
2.0 corresponds to sea-water of 35 PSU (maximum reading is
2.29999, corresponding to a salinity of approximately 42 PSU).
Table 2-2: Performance

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3-1
3. OPERATING DATA
3.1. MEASUREMENT THEORY
The instrument permits measurement of the electrical conductivity ratio of saline samples at a
controlled temperature. Once measured, the conductivity ratio can be used to determine salinity
through the use of a conversion table or the application of a mathematical equation.
Low pressurized air forces the saline sample from the sample bottle and through the sampling
element which is called a conductivity cell. The sample passes as a continuous flow through the
conductivity cell. Electrodes implanted in the cell initiate signals that are proportional to the
sample's conductivity. Using an internal preset electrical reference to produce an error signal, the
instrument provides a numerical readout, which corresponds in magnitude and direction to the
error signal. The display reading provides a valid measurement value when the internal
reference has been preset, or standardized, against a known external reference. Standardization,
using IAPSO recognized sea-water standards, is accomplished by operating the instrument as for
a routine conductivity ratio measurement with the standard sea-water and making adjustments as
necessary to the instrument so that the reading corresponds with the known conductivity ratio for
that particular standard seawater.
In practice the instrument is calibrated so that the displayed reading is a 2 to 1 conductivity ratio
of the measured sample to standard sea-water. The resolution of the instrument is such that the
last digit is approximately equivalent to 0.000 2 PSU at 35 PSU. At this level of accuracy,
fluctuation of the last digit by up to five counts (±0.001 PSU is of minor significance to the total
reading.
In preparation for measurement of the conductivity ratio the following two functions are initiated
by the operator:
(a) Temperature selection - to enable the sample temperature to stabilize at a precise preset
level prior to the conductivity ratio measurement;
(b) A flushing action - to enable systematic purging of the conductivity cell, thereby ensuring
that no residue from the previous sample remains. Residue from the previous sample
would degrade sample purity. Not more than 100 ml is required to measure any sample,
starting from fresh water in the conductivity cell and including flushing volume. Only
50 ml is required if the difference in salinity from the previous sample is not greater than
3 PSU.
Due care must be exercised in preparation and handling of samples in order to ensure accurate
results. For instance, a single drop of rainwater in a sample bottle, or mere hand contact
introducing salts from skin moisture into the sample water, may be enough to cause measurable
errors in salinity.

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3-2
Figure 3.1: Laboratory Salinometer Flow Diagram

Section 3
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3-3
3.2. SAMPLE WATER FLOW ARRANGEMENT
The tank configuration is shown in Figure 3.1. The tank is insulated with polyethylene foam and
has a gasket seal around the top. It has a rectangular cross section with a divider in the middle
and a smooth curved bottom to reduce turbulence and avoid dead zones. Bath circulation is
achieved by an impeller driven by a small motor mounted above the tank. Bath volume is about
17 litres and cycle time for the water is about 15 seconds. The sequence of water flow is from
the impeller to the heat exchanger coil which is mounted near the tank divider then to the cell. In
the space between the heat exchanger and the side of the bath are two 40-watt tubular
incandescent lamps located so that any water heated passes the impeller for mixing before
striking any critical component. On the side of the bath, by the lamps, is the cold element of a
thermoelectric cooling unit which runs continuously. Two thermistors located near the
conductivity cell act as the temperature sensors. A bulb behind the front panel illuminates the
conductivity cell.
The sample bottle is placed in the holder with its neck pressing against an air seal and the thin
Teflon pick-up tube projecting almost to the bottom. Making the seal allows low pressure air
from a pump to build up pressure above the sample, forcing a slow flow (30 ml/min) through the
pick-up tube into a coil of stainless steel heat exchange tubing which is mounted in the precisely
thermostatted water bath. The flow of the sample, now at bath temperature, passes through a
Teflon tube to the Pyrex conductivity cell. Once the cell is filled the sample exits from the other
end of the cell through a plastic tube and out of the tank to a larger tube which leads to a drain
spigot.
The four electrodes of the cell are platinum-rhodium coils mounted in side arms spaced along the
upper side of the cell as shown. The two outer arms are used as potential leads and the inner
arms as current leads. In addition to the electrical lead each side arm accommodates a very fine
Teflon tube which serves as an air vent so that the side arm can fill with water. The cell is
mounted at an angle of about 15° allowing the cell to be emptied by forcing air down the Teflon
tubes into the side arms. Back flow of water in the heat exchanger is prevented by the higher
filling pressure. After flushing, the cell refills via the inlet tube with the first water running
along the bottom of the cell to clean out the previous water. As soon as the cell has been filled
above the electrodes, readings can be taken, or, alternatively, a new flush can be started.
The end of the pick-up tube in the sample bottle is located slightly lower than the conductivity
cell; consequently, if the cell empties just before removing the bottle the water in the tube will
siphon slowly away from the cell thus causing backflow of old sample into the new one. To
prevent the backflow of sample water, a Mylar pickup tube holder has been provided. Insert the
pickup tube into the holder to initiate siphoning towards the cell. Once the sample water reaches
the bend in the pickup tube, it will continue to siphon towards the cell. This also creates a plug
of air to separate the old and new water in the heat exchanger. The thermostatted bath has a
window facing the operator to allow full viewing of the cell.

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3-4
Air pressure for driving the water and for cell flushing is provided by two piston type pumps,
which can be switched on or off. Flushing is initiated by blocking a panel mounted control
orifice, thus diverting the air to the electrode arms and driving the water out of the cell.
3.3. BATH TEMPERATURE CONTROL
A precision control system maintains the bath water temperature at one of six selectable settings
in the range 18°C to 33°C in increments of three degrees. Two incandescent bulbs provide the
bath heating source while a thermoelectric cooling unit provides the cooling. Steadily lighted
during a "heat on" cycle and darkened during a "heat off" cycle, the heater lamps flash on and off
in regular sequence, providing visual indication when bath temperature reaches the selected
setting. The temperature control range enables cooling of the bath to room temperature minus
2°C and heating to room temperature plus 4°C.
3.4. SAMPLE FLOW RATE
It is not possible to obtain a stable reading from a sample which has not achieved bath
temperature due to a combination of a large sample to bath temperature difference and a high
flow rate. If the flow rate is too fast the heat exchanger will be unable to bring the sample to the
correct temperature. Unstable or incorrect readings will result. If the flow rate is too slow an
excessive amount of time will be required to fill the cell and to obtain a reading. If the flow rate
is too fast the indication will be a marked change in the cycling of the heater lamps. A cold
sample will cause an "ON" period. The flow rate should be reduced until the normal cycling of
the heater lamps is restored.
3.5. CONDUCTIVITY MEASURING CIRCUIT
A simplified schematic diagram of the conductivity measuring circuit is shown in Figure 3.2.
The circuit measures the resistance of the cell by maintaining a precise voltage across the
potential arms of the four terminal resistor (cell) and measuring the voltage across a stable
resistor in series with the cell current arms. The current is a square wave alternating current to
prevent polarization of the sample.

Section 3
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1 November 2004
3-5
Figure 3.2: Conductivity Measuring Circuit

Section 3
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3-6
The following references are to Figure 3.2. The precision reference generates precise stable +1
and -1 volt references. The chopper (U209) is driven by the clock signals to alternate the two
reference values and provide a low frequency square wave ±1 volt signal. U208A buffers this
reference, and drives the cell voltage comparator circuit and the suppression resistor chain. The
voltage across the cell resistance is monitored by buffers U200 and U203. These signals are
summed with reference signal (U208A), and a DC bias signal from U208C and fed to U208B
which provides the cell current to keep the voltage between P1 and P2 constant and equal to the
reference voltage. U208D keeps P2 at ground potential - sinking or sourcing current as
necessary. Keeping P2 at ground potential prevents a leakage current to the heat exchanger
which is also at ground potential. In the cell current path, Rcell is the conductivity cell, Rs is the
standardization resistor Rtemp is the temperature compensation resistor chain, Rmatching is the
precisely cut cell matching resistor. The voltage across the matching resistor and the selected
temperature compensating resistance is buffered by U205A and U205D. U205B is an inverting
gain stage. The voltage level from the suppression chain is buffered by U205C, and the three
signals are summed by U207 to provide a signal proportional to the conductivity of the cell. The
dechopper (U212) rectifies and smooths the AC signal to provide a DC signal, and U206
provides a final gain and offset compensation stage. The same precision reference is used for the
reference of the analog to digital convertor.
3.6. DISPLAY CIRCUITRY
The output from the conductivity measuring circuit is changed to a binary coded decimal number
by the meter circuit (16504.01.04). This number is displayed on a 4 digit LED (light emitting
diode) readout and is available for electronic data logging through the rear panel BCD connector.
The analog to decimal conversion is performed by a commercial 4½ digit analog to digital
integrated circuit system.

Section 4
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1 November 2004
4-1
4. CONTROLS AND INDICATORS
4.1. GENERAL
All primary instrument controls and indicators are located on the front panel. The main power,
voltage select switch and main supply fuse are mounted on the rear panel exterior. Figure 4.1
identifies the front panel controls and indicators as well as some other functional items.
4.2. CONTROLS
(a) FLOW RATE: This valve regulates the flow of the sample water by controlling
the air pressure in the sample bottle. A flow rate of 30 ml/min is available with flow rate
valve at maximum (valve fully clockwise). Decreasing the flow rate allows more time for
the sample temperature to equal bath temperature before sample water enters the
conductivity cell.
(b) TANK DRAIN: This valve must be open (fully counter-clockwise) when filling or
draining the tank through the TANK DRAIN/FILL spigot; closed when filling through
top tank opening and for all other operations.
(c) CHECK HEATER: This indicator lights continuously when one of the heater lamps is
open circuit.
(d) PUMPS: This switch is normally left in the OFF position unless filling or
flushing the conductivity cell.
(e) TEMPERATURE-SET C: This six-position switch selects 18°C, 21°C, 24°C, 27°C,
30°C or 33°C bath temperatures. The bath temperature must be set within -2°C to +4°C
of room temperature.
(f) TEMPERATURE SENSOR: This three-position switch is left in the NORMAL
position except to check thermistor sensor operation when positions 1 and 2 are used.
(g) STANDARDIZE: This ten-turn vernier potentiometer (with 100 divisions-per-turn
scale and locking arm) is used with the FUNCTION switch in the READ position when
standardizing the instrument.
(h) FUNCTION: This switch has three positions. In the ZERO position, the display
indicates if the zero reference has drifted. In the READ position, the display indicates
twice the conductivity ratio of the sample to the standard. In the STANDBY position, the
first two digits of the display indicate the setting of the TEMPERATURE SET °C
switch. A change in the reading of the last four digits indicates the STANDARDIZE
control setting has changed or the electronics has drifted from the last standardization.

Section 4
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4-2
(i) SUPPRESSION: This 23-position switch is used with the FUNCTION switch in the
READ position to obtain the first two digits in the display during measurement and
standardization. This control acts as a range switch. Whenever the saline sample is
outside the range of the SUPPRESSION switch setting, the display flashes on and off.
This control is adjusted until the display indicates a positive reading and ceases to flash.
(j) FLUSH: This air vent controls the air pressure in the conductivity cell
flushing manifold. Covering the vent with the finger causes the sample water in the
conductivity cell to discharge through the CELL DRAIN spigot.
(k) 115 V/230 V: Located on rear panel, this switch is used to prepare the instrument
power circuits so as to accept either 115 V or 230 V main supply.
(l) DATA LOG: Momentary pushbutton switch provided with the BCD output to
enable a trigger signal for an external device (printer, recorder, computer etc.).
(m) POWER: This switch, located at the rear next to the line cord receptacle, is
normally left on to maintain water bath temperature.
4.3. INDICATORS
(a) DIGITAL DISPLAY: The display is arranged as follows: digit, decimal point,
digit, + or - sign, digit, digit, digit, digit. The position of the FUNCTION switch
determines what is displayed. The decimal point appears only when the FUNCTION
switch is in the READ or ZERO position.
(b) BOTTLE NUMBER: This four-section thumb wheel switch provides a
mechanical numeric display to identify the sample. It is used with the DATA LOG
pushbutton for data logging samples via the BCD OUTPUT connector.