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Anderson Instrument Co. Inc.
Instruction Manual
Instrument Model Number ________________________________
Instrument Serial Number ________________________________
156 Auriesville Road
Fultonville, NY 12072
1-800-833-0081
Fax 518-922-8997
DIGITAL REFERENCE
THERMOMETER
(DART)
Form Number AIC3329
© March 1994
Revised: October 2016
Supersedes: February 2011
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Table of Contents
SECTION 1 - DESCRIPTION PAGE
1.1 General 4
SECTION 2 - INSTALLATION
2.1 Mechanical 5
2.2 Electrical 5
2.3 QDR – Quick Disconnect Receptacle Wiring 8
SECTION 3 - TESTING PROCEDURES
3.1 Accuracy 9
3.2 Speed of Response 10
3.3 Additional Tests 10
SECTION 4 - TROUBLESHOOTING
4.1 Troubleshooting and Repair 12
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APPENDICES
A - Specications 13
FIGURES
Figure 1 Dimensional Drawing 6
Figure 2 Power Board 7
Figure 3 Display Board 9
Figure 4 Sensor Wiring Conguration 10
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Section 1 - Description
1.1 GENERAL
The Digital Reference Thermometer (DRT) was developed as a replacement for the analog
Mercury-In-Glass (MIG) thermometers required by the Pasteurized Milk Ordinance (PMO) for
verifying pasteurization temperatures. The MIG thermometer has historically been the only
acceptable reference due to several criteria inherent in the design. Among these are readability, accuracy, speed-of-response and the fail-safe aspects of MIG thermometers. Each of
these criteria has been addressed in the proprietary design of the DRT.
The DRT incorporates a 1/2" LED display with 4 1/2 active digits. This provides a readable
display at a much greater distance than the MIG thermometer. In the Fahrenheit mode, 1/10
degree resolution is provided (1/100th in °C) insuring no operator interpolation errors as is
possible with the MIG thermometer. The DRT display is housed in a panel or wall mount
enclosure for mounting exibility. It is expected that the thermometer will be located where it
can be most easily monitored and checked.
The dual element temperature sensor utilizes 4-wire circuitry, thus providing greater accuracy
than conventional 2 or 3 wire sensing elements.
The DRT monitors both sensor signals simultaneously, comparing them electronically to
insure they track one another within ± .50°F (.30°C). If in balance within the prescribed limits,
the primary signal is displayed. If outside these limits, the logic circuit causes the display to
blank. This provides fail-safe operation comparable to an MIG thermometer. In addition,
separate watchdog circuitry monitors for proper sensor wiring. An "open" or "short" circuit
also causes a blank display until wiring is repaired.
The DRT is designed to provide a response characteristic which meets the existing regulations. Based on repeated testing of a number of units, the average response is about three
seconds for the standard test. See Section 3.2 for outline of the procedures.
Diagnostic indicator lights for power, inhibit and failure modes are provided within the instrument for troubleshooting purposes.
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Section 2 - Installation
2.1 MECHANICAL
Refer to Figure 1, page 5 for dimensions and mounting schematics. Choose a location for the
display which allows the thermometer to be viewed from the control panel and/or the Safety
Thermal Limit Recorder. The case may be wall or panel mounted. Protect the display from
direct hose-down conditions.
The thermometer will be shipped with the specied length of pre-wired cable. If disconnected
for ease of installation, reconnect by referring to Figure 2, page 6. Allow enough excess
cable at the sensor end to allow the probe to reach the oor for testing purposes. In addition,
if enough excess cable is available to bring the probe within sight of the indicator for testing,
the procedure will be simplied. Any excess cable at the sensor should be tightly coiled, tie-
wrapped and hung in a protected position.
2.2 ELECTRICAL
Electrical code requirements and safety standards should be observed.
Bring 100 VAC power, with ground through the 1/2" penetration in the base of the instrument.
Route the power lead to the lower left corner of the case. Connect the three leads as shown
in Figure 2, page 6.
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If the sensor input leads have been disconnected for external routing, bring the cable back
through the rubber grommet and reconnect by color code as shown in Figure 2, page 6.
Shortening the cable is acceptable but care should be taken to insure none of the leads are
"nicked" when stripping insulation. Tinning of all leads is recommended.
After wiring is completed, position the F/C switch for Fahrenheit or Centigrade operation. The
switch is located on the display board just to the right of the display.
Note: If RTD is replaced, reconnect cable by color code, see Figure 4, page 8.
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FIGURE 1
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FIGURE 2
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MAIN FUSE 1/8 A SLO-BLO - 3AG (1-1/4")
PROBE FAIL
GREEN L.E.D.
POWER INDICATOR
RED L.E.D.
YELLOW L.E.D.
115 VOLT A.C. POWER 741 SENSOR INPUTS
TEST SWITCH
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2.3 QDR – QUICK DISCONNECT RECEPTACLE WIRING
When used for applications not required to meet Pasteurized Milk Ordinance standards, the
DART may be supplied with a QDR (Quick Disconnect Receptacle). Retort cookers and other
non PMO processes are examples of where this conguration may be used. Wiring this way
allows the cable to remain in place, but disconnected from the sensor and display enclosure.
This is useful for systems with long cable lengths where it is desirable to perform a calibration
of the DART display and sensor at another more convenient location.
PIN8
BLUE
BLACK
PIN 3
GREEN
PIN 2
WHITE
PIN4
PIN 1
RED
PIN5
ORANGE
PIN 6
YELLOW
PIN 7
BROWN
Figure represents QDR found on DART display enclosure
as well as DART dual element sensor.
Color codes correspond to display enclosure inputs found
on Figure2of this manual, as well as sensor terminals found
on Figure4of this manual.
PIN 4
YELLOW
PIN5
GRAY
PIN 6
PINK
PIN 3
GREEN
PIN7
BLUE
PIN 2
BROWN
PIN8
RED
PIN1
WHITE
Wire color codes apply when molded
cord supplied by Anderson, and terminated
using Field Wireable Connector as shown .
Be sure to verify proper pin connections and
color codes if using Customer supplied cabling.
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Section 3 - Testing Procedures
3.1 ACCURACY
Accuracy tests may be performed using documented procedures for existing MIG thermometers. Several important guidelines will insure the most repeatable results.
Note: A "stress" test, although not applicable, may be performed by exposing the
probe to ice water and then boiling water.
GUIDELINES FOR ACCURACY TESTS
1. Use a well agitated and maintained temperature bath at or near the normal operating
temperature for the system.
2. Verify the bath temperature using a certied "lab" thermometer. If the "lab" is a full-
immersion type, be certain to immerse it fully.
3. Locate the calibration bath at a point from which the DRT display is readable. If this is not
possible, a second person will be required to check the DRT against the "lab".
4. Allow at least ve minutes for the bath and both thermometers to stabilize. The large
stainless steel probe will tend to cause slight cooling of the bath upon immersion.
5. Document the DRT display temperature once it has stabilized. At this point the display
should be varying by ± .1°F (± .06°C) or less.
6. If the DRT display is reading in agreement with the "lab", or lightly less (within .2°F), the
DRT is well within calibration specication. The only unsealed adjustment potentiometer
(or "pot") on the display board (labeled "O" in Figure 3), may be used for small zero
adjustments of the display. Errors of greater than .5°F (.5°C) require:
1. Installation of a new probe or
2. Factory Calibration
FIGURE 3
TEMPERATURE DISPLAY
CUSTOMER
"FINE" ZERO
°F/°C INDICATOR
°F/°C SELECTOR
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3.2 SPEED OF RESPONSE TEST
As with the accuracy test, documented procedures apply. Again, a few critical guidelines will
insure satisfactory results:
1. Reading the display accurately for start/stop of the stopwatch can be troublesome with the
tenths (in °F) or hundredths (in °C) showing. Place a small piece of non-transparent tape
(masking or electrical will work) over the digits to the right of the decimal point before
performing this test.
2. The degree of agitation in the bath will greatly affect response time results as with the MIG
thermometer. Approximating the ow-rate of product in a typical holding tube requires a
high degree of agitation. The DRT is designed to meet the response criteria even with
relatively slow agitation. If unsatisfactory results are achieved, test the response again,
stirring the bath with the probe itself. Document the response time and contact the factory
with the results.
3. Due to the rapid digital response, the calculated temperature for starting the watch may
actually be "skipped" upon immersion of the probe. In this case, retest using a starting
temperature 1°F (.6°C) below the original. This will allow starting the watch at a displayed
temperature rather than a "phantom". Expect a slightly longer response time since the test
will be for a 13°F (7.2°C) change rather than a 12°F (6.6°C) change. The response
should still be within the four second limit. If not, contact the factory.
3.3 ADDITIONAL TESTS
1. The diagnostic comparator circuit is provided with an inhibit/fail test button, see Figure 2,
page 6. At any stable temperature (ice water works well for this), this button can be
pushed and held. Within fourteen to twenty seconds, the display will blank. Pushing the
button simulates a sensor imbalance combined with a very fast temperature change. If the
display blanks at a time longer than twenty seconds, or does not blank, contact the factory.
2. Sensor Check: With the DRT operating at a stable temperature (ice water again will work
well), note the displayed temperature. Locate the two sensor input plugs in the lower right
of the instrument, see Figure 2, page 6. Remove and reinstall both plugs in the opposite
position (yellow wire will now be in the furthest right position). Display should read within
.1°F (0.5°C) of the temperature noted above. If not, contact factory.
FIGURE 4
SECONDARY
YEL
BLU
BRN
ORG
PRIMARY
RED
GRN
WHT
BLK
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Effect of Ambient .018°F for 10°F (.01°C for 5.55°C) typical
Temperature Change
Effect of Line Voltage None (from 85-138 VAC)
Change
Long-Term Stability Within ambient temperature range of 50°F to 90°F (10°C to 32°C)
(Electronics only) less than 0.5°F (0.28°C)
Power Consumption 5 watts maximum
Power Loss Reserve .1 second or six cycles minimum.
Time (Condition: voltage prior to loss at least nominal 115V)
Note: Display will "blank" before reading loses accuracy.
Warm-Up Time 1 hour to meet stated specications.
Initial Accuracy Upon ± .1°F (± .06°C)
Power Up
Integrity Display is readable ("On") only when the two measured
temperatures are within .5°F (.28°C). Error limit includes both
sensor and display electronics.
Note: A calibration check module may be purchased
optionally to verify calibration precision.
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Display Blanking For operator convenience, the .5°F agreement error limit
Delay (Inhibit) is automatically waived during large, rapid temperature swings.
Maximum inhibit time is approximately 15 seconds.
Faulty Probe Wiring Immediately detected by "watchdog" circuit causing "blank" display
(no inhibit).
DISPLAY UNIT AND SENSOR
Calibrated Accuracy: ±0.22°F from 32°F-212°F (±0.12°C from 0°C-100°C), ±0.45°F
from 212°F-302°F (±0.25°C from 100°C-150°C) including drift,
linearity and repeatability
Stability Stable within above limits for at least 3 months
Calibration Adjustment "Fine" zero (± .28°F to 0.5°F) only; tracks for °F and °C, easily
accessible. All factory adjustments are sealed.
Speed of Response Within four seconds for standard PMO test
Pasteurized Milk Ordinance, Appendix I, Test 7
Interchangeability of Changing, adding, or subtracting cable length has no effect
Cable on system specications
Fuse Rating 1//8 AMP SLO-BLO (3 AG 1 1/4")
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Section 4 - Troubleshooting
4.1 TROUBLESHOOTING AND REPAIR
The DRT is designed for ease for use and long-term repeatability. No actual repairs may be
performed in the eld. It is highly recommended that a spare probe be purchased with the instrument. Each probe is individually calibrated to an exact standard so replacement requires
no eld calibration. The spare probe works as a troubleshooting aid as well. Troubleshooting
is outlined below.
Problem Probable Cause Solution
Display not in 1. System not at stable 1. Wait for stability of system
agreement with STLR temperature. before checking.
2. STLR not in calibration. 2. Wait for stability, then
adjust pen to agree with
DRT. Test both in bath at
next opportunity.
DRT is found to be 1. Insufcient time in bath for 1. Wait for stabilization before
inaccurate during DRT and reference to checking.
testing against reference stabilize.
thermometer
2. DRT out of calibration 2. Adjust per section 3.1 or
contact factory.
Display is blank 1. System is in temperature ux. 1. Wait for system
temperature to stabilize.
2. Sensor probe imbalance. 2. Replace sensor probe,
test calibration and
response.
3. Problem with diagnostic 3. Contact factory.
circuit.
4. Probe beginning to fail or drift. 4. Press "test" button. See
explanation below.
5. Wiring not correct. Broken or 5. Check wiring (16
shorted wire. connections). Check
connectors in probe and
display.
4.2 TEST BUTTON PROCEDURE
If display is blank, depress test button. If probe wires are not shorted or broken, display will
come on for a few seconds. If it does not, probe should be replaced. If problem still occurs,
interconnecting cable is faulty and needs replacement. If display comes on for a few seconds,
note the displayed temperature. Swap the two sensor input plugs. Push the test button again
and note the displayed temperature. If the two noted displays differ by more than 1/2 degree
F, then the sensor is beginning to fail or drift and requires replacement.
Also, if a calibration test xture is purchased with the instrument, plug this into the unit to verify
its operation. If display unit works with the xture, check probe and wiring.
Note: If display is blank but the decimal point and/or degree F-degree C indicator is on,
115 VAC power is ok. If not, unit has no power.
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Appendix A - Specifications
SENSOR
Type Dual element (8-wire), Resistive
Material 316 Stainless steel
Finish Meets or exceeds 3-A sanitary standards (#09-08)
Process Connections Split ferrule or sanitary clamp type in a variety of sizes
Wiring Connection Integral conduit housing with cap sealable by health authority
Cable Length 25 feet standard; 1500 feet maximum
Stability Within .40°F (.22°C) per year
Linearity ± .036°F (0.02°C) from 0°C to 100°C
Interchangeability ± 0.1°F (± 0.06°C)
DIGITAL DISPLAY
Type Remote mount, wall or panel
Material Die-cast aluminum with two-part polyurethane paint
Closure Fully gasketed with provision for health authority seal
Dimensions See Section 2
Display 1/2" LED, 4 1/2 active digits
Power 115 VAC nominal; 50/60 Hz
85 VAC minimum
138 VAC maximum
Display Value Fahrenheit or Celsius (user selectable)
Display Range -148°F to 392°F (-100°C to 199.99°C)
Resolution 0.1°F (0.01°C)
Linearity ± 0.1°F (0.06°C)
Repeatability ± 0.1°F (± .01°C) at ambient temperature
Ambient Temperature 40°F to 120°F (5°C to 49°C)
Range
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Warranty and Return Statement
These products are sold by The Anderson Instrument Company (Anderson) under the warranties set forth in the following
paragraphs. Such warranties are extended only with respect to a purchase of these products, as new merchandise, directly
from Anderson or from an Anderson distributor, representative or reseller, and are extended only to the rst buyer thereof who
purchases them other than for the purpose of resale.
Warranty
These products are warranted to be free from functional defects in materials and workmanship at the time the products leave
the Anderson factory and to conform at that time to the specications set forth in the relevant Anderson instruction manual or
manuals, sheet or sheets, for such products for a period of three years for the digital display and one year for the sensor.
THERE ARE NO EXPRESSED OR IMPLIED WARRANTIES WHICH EXTEND BEYOND THE WARRANTIES HEREIN AND
ABOVE SET FORTH. ANDERSON MAKES NO WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR
PURPOSE WITH RESPECT TO THE PRODUCTS.
Limitations
Anderson shall not be liable for any incidental damages, consequential damages, special damages, or any other damages,
costs or expenses excepting only the cost or expense of repair or replacement as described above.
Products must be installed and maintained in accordance with Anderson instructions. Users are responsible for the suitability
of the products to their application. There is no warranty against damage resulting from corrosion, misapplication, improper
specications or other operating condition beyond our control. Claims against carriers for damage in transit must be led by
the buyer.
This warranty is void if the purchaser uses non-factory approved replacement parts and supplies or if the purchaser attempts
to repair the product themselves or through a third party without Anderson authorization.
Returns
Anderson’s sole and exclusive obligation and buyer’s sole and exclusive remedy under the above warranty is limited to repair-
ing or replacing (at Anderson’s option), free of charge, the products which are reported in writing to Anderson at its main ofce
indicated below.
Anderson is to be advised of return requests during normal business hours and such returns are to include a statement of the
observed deciency. The buyer shall pre-pay shipping charges for products returned and Anderson or its representative shall
pay for the return of the products to the buyer.
Approved returns should be sent to: ANDERSON INSTRUMENT COMPANY INC.
156 AURIESVILLE ROAD
FULTONVILLE, NY 12072 USA
ATT: REPAIR DEPARTMENT
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