Comark C21 - Manual (Page 2)

Low Alarm – the display will show ‘LOAL’
Use the countdown timer and hold buttons to select or de-
select low alarm, then select the required low alarm value.
Auto Power OFF
– the display will show ‘AOFF’
Use the countdown timer button and the hold button to scroll
between the available options of 3, 10, 30 minutes or none.
Clock Alarms
– the display will show AL 1, followed by
AL 2 and AL 3
Three Clock Timer Alarms can be set. Use the countdown
and hold buttons to select or deselect Clock Alarm, and then
to select the required time. Note that on instruments with no
AM or PM indicator it will show the change by the way the
time changes over midnight or noon. At midnight the display
will change from 11:59 to 0:00, indicating AM, and at noon the
display will change from 11:59 to 12:00, indicating PM.
Repeat for AL 2 and AL 3.
Resolution
– the display will show ‘HrES’
Use the countdown and hold buttons to select or de-select
temperature display in high resolution 0.1° or low resolution
1°.
Care of the Thermometer
C20 series thermometers are dust and splashproof and will
withstand harsh environments. Use a damp cloth or warm
soapy water to remove deposits and prevent them from
hardening or becoming sticky. Do not use solvent-based
cleaners or methylated spirit, etc.
Caution: Do not place any C20 series thermometers in a
dishwasher.
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Changing the Batteries
The symbol BAT appears on the display when the battery
voltage has reduced. Battery replacement is recommended at
this time.
To replace the battery, remove the battery cover retaining
screw on the rear of the instrument, using the correct size
screwdriver. Remove the two cells, and replace with alkaline
cells only. Be careful to observe the correct polarity. Take
care not to over-tighten the screw when refitting the cover.
Note: The C20 series thermometers will not work if the battery
compartment is incorrectly fitted or missing. In this instance
the display will show ‘OPEn’. Please note the small pip on the
inside of the battery cover, which must fit into the hole
provided in the back of the case.
Specifications for C20 Series Thermometers
Measurement
Thermistor 10 K Ohms unicurve
Thermocouple type T and K
6-pin Lumberg and Sub-Min Connectors
Measurement Range
-50°C(-58°F) to +150°C(302°F) Thermistor
-200°C(-328°F) to 400°C(752°F) Type T
-200°C(-328°F) to 600°C(1112°F) Type K
Scales
°C and °F
Displayed Resolution
0.1° > -100°
1°  -100°
Instrument Accuracy
Thermocouple
0.1% ± 0.2°C(0.4°F) full range
@ 23°C Ambient
Thermistor ±0.3°C (±0.6°F)
System Accuracy
0°C (32°F) to 70°C (158°F)
±0.5°C (±0.9°F)
-25°C (-13°F) to 100°C (212°F)
@ 23°C Ambient
Temperature Coefficient
Thermistor
less than 0.005°C/°C (0.01°F per °F)
Thermocouple less than ± 0.01 % of reading ±0.02 °C per °C
(±0.04°F per °F) change from 23°C
5
Specifications Continued
Ambient Temperature Range
-20°C (-4°F) to +50°C (122°F) operating
Display
4 digit, 12.5 mm LCD
Battery
Two Type I.E.C. LR6 Size AA
Battery Life (continuous) Up to 14000 hours with thermistor probes
Up to 7000 hours with thermocouple probes
EMC Emission
Tested to EN61326-1
Criteria B Performance
Dimensions
Length
152mm/6 inches
Width
58mm/2.3 inches
Depth
22/27mm/09./1.1 inches
Weight
178g/6.3 ozs
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Appendix 1
– C20 Series Model Range Options
Models C21 C22
C22 T
Type
C26
C28 K
Type
Part No. C21 C22 C22F C26 C28F
Options
Countdown
Timer
    
Data Hold     
Real Time
Clock
    
Clock Alarms - - - - 
Scale
Selection
    
High Alarm - -  - 
Low Alarm - -  - 
High
Resolution
    
Type T -    -
Type K - - - - 
Thermistor    - -
Connector* L L L S S
Auto Off     
Splashproof     
* L
– Lumberg
S – Sub-Miniature
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