Digi-Sense 20250-91 User manual

User Manual
THE STANDARD IN PRECISION MEASUREMENT
Single-Input Thermometers
with NIST-Traceable Calibration
Thermocouple Meter, Type J/K/T Input
Model 20250-91
Thermistor Meter
Model 20250-93
RTD Meter
Model 20250-95

3
Introduction
The Digi-Sense Professional Single-Input Thermometers
(20250-91, -93, -95) offer fast response and laboratory
accuracy. Features include automatic backlight, Max/Min
readings, and automatic power-off. The instrument is fully
tested and calibrated to NIST-traceable standards. Careful
use of this meter will provide years of reliable service.
Unpacking
Carefully unpack the instrument and accessories from ship-
ping package. Check individual parts against the list of
items below. If anything is missing or damaged, please
contact your instrument supplier immediately.
1. Meter
2. Soft carrying case
3. Lanyard
4. One 9 volt battery
5. User manual
6. NIST-traceable calibration report with data

4
Key Features
• Large backlit display
• Max and Min readings
• Data Hold
• Electronic Offset function allows compensation
of errors to maximize overall accuracy
• User-selectable readout in °C or °F
• Automatic power-off (sleep) mode to conserve
battery life
• Accept a wide range of probes

5
Meter Description
1. LCD
2. Down () button
3. Data HOLD button
4. MIN button
5. User-selectable temperature
units (all models); backlight
button (20250-91 only)
6. Power on/off button
7. CAL (offset/calibration)
button
8. MAX button
9. Up () button
10. Temperature sensor
input
11. Type JKT button
(20250-91 only);
backlight button
(20250-93 and -95 only)
20250-91 20250-93 and -95

6
Display Layout
1. Thermocouple type JKT
icon (20250-91 only)
2. HOLD icon
3. Low-battery indicator
4. User-selectable
temperature units
(°C or °F)
5. Primary display (current
or Hold readings)
6. MAX icon
7. MIN icon
8. Secondary display
(Max or Min readings)

7
Setup and Operation
Measuring Temperatures
1. Plug the probe into the T1 input connector. Make
sure that the polarity is correct.
2. Press power on/off button to turn on the thermom-
eter. After one second the thermometer displays
the first reading. The screen will display the current
measured value and the maximum temperature.
3. If no probe is plugged into the selected input or the
probe is not connected properly, the display shows
"- - - -". If the temperature being measured is out-
side the meter’s valid range, the display shows
“OL” (overload).
Thermocouple Input Function (20250-91 only)
1. Press JKT button to set the correct thermocouple
type as J, K, or T.
Backlight Function
1. Press Backlight/°C/°F button for 2 seconds to
turn on or off the backlight (20250-91 only).
2. Press Backlight button to turn on or off the
backlight (20250-93 and -95).
Temperature Units Function
1. Press °C/°F button to toggle between temperature
scales.

8
Setup and Operation (continued)
Hold Function
1. Press the HOLD button to freeze the readings on
the display. The display shows the HOLD icon.
2. Press the HOLD button again to turn off the
Hold function.
3. The Hold function does not freeze the Max or Min
function or stop the meter from updating.
Max/Min Function
1. Press MAX or MIN button to display the maxi-
mum (Max) or minimum (Min) readings on the
secondary display.
2. The display shows the related MAX or MIN icon.
3. Simultaneously press the Up () and Down ()
buttons to recalculate the stored maximum and
minimum values in the meter.
Auto Power-Off (APO) Mode
1. The meter’s default mode is to automatically shut
off after 15 minutes of non-use.

9
Offset/Calibration Function
Using the Offset to Adjust for Probe Errors
Use the offset/calibration function to adjust the meter’s
readings to compensate for the errors of a specific
sensor. The allowable adjustment range is ±9.0°F or
±5.0°C.
1. Plug the probe into the meter’s input connector.
2. Place the probe in a known, stable temperature
environment (such as an ice bath).
3. Allow the readings to stabilize.
4. Adjust the offset until the primary reading matches
the calibration temperature.
Adjusting the Offset
The primary display shows the temperature plus the
offset and the secondary display shows the offset.
1. Press the CAL button for 3 seconds to enter user
calibration mode.
2. Press the Up () or Down () buttons to adjust the
offset by 0.1°. The max offset value is 5°.
3. Press the CAL button to save the setting and return
to normal measurement mode.

10
Specifications
Sampling rate: Three times every two seconds
Auto power-off: Unit shuts off automatically after 15 minutes
to preserve battery life
Operating temperature: 32 to 122°F (0 to 50°C)
Storage temperature: 14 to 122°F (–10 to 50°C)
Weight: 6.2 oz (177 g)
Dimensions: 7" x 21⁄4" x 1" (17.8 x 5.7 x 2.6 cm)
Power: One 9 volt battery
Range Resolution Accuracy
Thermocouple meter 20250-91
Type J: –328 to 1832°F
(–200 to 1000°C) 0.1°F (0.1°C) from –148 to
1832°F (–99.9 to 999.9°C);
1°F (1°C) outside range
±1 of reading + 1.8°F (1°C)
below –148°F (–99.9°C);
±1 of reading + 0.9°F (0.5°C)
above –148°F (–99.9°C)
Type K: –418 to 2501°F
(–250 to 1372°C)
Type T: –418 to 752°F
(–250 to 400°C)
Thermistor meter 20250-93
–40 to 257°F
(–40 to 125°C) 0.1°F (0.1°C) ±0.9°F (±0.5°C) from
32 to 158°F (0 to 70°C);
±2°F (1°C) outside range
RTD meter 20250-95
–320 to 1562°F
(–200 to 850°C)
0.1°F (0.1°C) from –148 to
1562°F (–99.9 to 850°C);
1°F (1°C) outside range
±1.5°F (0.8°C) from –148
to 392°F (–99.9 to 199.9°C);
±2°F (1°C) + 0.5% of reading
outside range

11
Maintenance, Recalibration, and Repair
Cleaning and Storage
• The meter should be cleaned with a damp cloth and
mild detergent when necessary. Do not use solvents
or abrasives.
• Store the meter in an area with moderate temperature
and humidity (refer to the operating and storage ranges
in the specifications chart earlier in this manual).
Battery Replacement
When the battery power falls low, the low-battery icon will
appear on the screen. Replace the one 9 volt battery by
removing the screw holding the rear battery compartment
cover to access the battery compartment. Ensure that the
compartment cover is securely fastened when finished.
Note: If you do not intend to use thermometer for a long time,
remove the batteries.
It is recommended that Digi-Sense products are calibrated
annually to ensure proper function and accurate measure-
ments; however, your quality system or regulatory body
may require more frequent calibrations. To schedule your
recalibration, please contact InnoCal, an ISO 17025 calibra-
tion laboratory accredited by A2LA.
Phone: 1-866-INNOCAL (1-866-466-6225)
Fax: [phone]
E-mail: [email protected]
Web: InnoCalSolutions.com

For Product and Ordering Information, Contact:
1065DGMAN_20250-91,-93,-95 Manual Part No. 00100-21
[e-mail]
www.novatech-usa.com
Tel: [phone] Fax: [phone]
Tel: [phone] Fax: [phone]