Page 1
Data sheet
testo 645
Humidity/temperature
measuring instrument
testo 645 – Highly precise
measurements for industry
Highly accurate humidity measurement up to ±1 %RH
Connection of 2 plug-in probes
Measurement of temperature, relative humidity and
pressure dewpoint
Internal measurement store (3000 measurement values)
PC software for the analysis, archiving and documentation
of the measurement values (option)
Button for Hold, min./max. values, mean value calculation
Convenient data analysis
The highly accurate thermal hygrometer testo 645 has two
probe inputs for the connection of an extensive range of
probes:
- Channel 1: temperature Type K/J/S, NTC
- Channel 2: combi probe humidity/temperature or
temperature probe Pt 100
The measuring instrument automatically displays the
measurement parameters temperature, relative humidity,
dewpoint, pressure dewpoint, absolute humidity, degree of
humidity and enthalpy, and additionally presents the current
values, the last measured values, min., max. and mean
values at the press of a button.
%RH
°C
Measurement data can be stored by measurement site
in the testo 645, and analyzed on a PC, or documented
using the Testo fast printer (option). The TopSafe (option) is
available for tough applications. The measuring instrument,
probes and accessories can be stored safely and tidily in
the transport case (option).
www.testo.com
Page 2
testo 645
Technical data
General technical data
testo 645
testo 645, humidity/temperature measuring
instrument, with battery
Part no. 0560 6450
Operating temperature 0 to +50 °C
Storage temperature -20 to +70 °C
Display LCD, 4 lines
Battery type 9V block battery
Battery life 45 h
Dimensions 215 x 68 x 47 mm
Weight 255 g
Housing material ABS
Accuracy of temperature: ± 1 digit at +22°C
Ni 10000 sensor: meas. range: ...+180 °C
Typical battery lives: 9V block (Al-Mn) 20-45h.
The hour times are reduced by a factor of 5 if a 9V rech. battery is
used
Calculated humidity parameters: td, g/m³, g/kg, J/g (pressure
compensated)
Mains connection and battery recharging in instrument
Save data by measurement site
and analyze on a notebook
Connections for temperature
probes Type K/J/S, NTC and
combi probe humidity/temperature
or temperature probe Pt100
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testo 645
Technical data / Accessories
Measuring rangeSensor type Accuracy ±1 digit Resolution
Testo humid. sensor,
cap.
Pt100 -200 to +800 °C ±0.1% of m.v. (+200.1 to +800 °C)
Type K (NiCr-Ni) -200 to +1370 °C ±0.5% of m.v. (-200 to -60.1 °C)
Type S (Pt10Rh-Pt) -50 to +1700 °C
Type J (Fe-CuNi) -40 to +750 °C
NTC -50 to +150 °C 0.1 °C (-50 to +150 °C)
Accessories Part no.
Transport and Protection
Transport case (plastic) for measuring instrument, probes and accessories
for safe and orderly storage
TopSafe (indestructible protection case), with bench stand and belt clip
0 to +100 %RH See probe data 0.1 %RH (0 to +100 %RH)
0.1 °C (-200 to +800 °C)
±0.2 °C (-200 to +200 °C)
0.1 °C (-200 to +1370 °C)
±0.5% of m.v. (+60.1 to +1370 °C)
±0.3 °C (-60 to +60 °C)
±0.5% of m.v. (-200 to -60.1 °C)
±0.5% of m.v. (+60.1 to +1370 °C)
±0.3 °C (-60 to +60 °C)
0516 0445
0516 0440
Printer and Accessories
Testo fast printer IrDA with wireless infrared interface; 1 roll thermal paper; 4 AA batteries
Spare thermal paper for printer (6 rolls), permanent ink
measurement data documentation legible for up to 10 years
Software and Accessories
ComSoft Professional Pro software incl. data archiving
RS232 cable connects instrument to PC (1.8 m) for data transfer
0554 0549
0554 0568
0554 1704
0409 0178
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testo 645
Accessories
Additional accessories and spare parts
Measures equilibrium moisture in bore holes
Testo humidity probes
Calibration Certificates
Calibration points 11.3 %RH and 75.3 %RH at +25 °C
saturated saline solutions: calibration point 11.3%RH
saturated saline solutions, calibration point 75.3%RH
electronic hygrometers; calibration points 11.3%RH and 75.3%RH at +25°C
Part no.
0554 1143Desk-top power supply with international connection options
0515 00259V rech. battery for instrument, instead of battery
0430 0143Cable, 1.5 m long, connects probe with plug-in head to meas. instrument, PUR coating material
0409 0063Extension cable, 5 m long, between plug-in head cable and instrument, PUR coating material
0554 2140Cap for bore holes, for humidity probe Ø 12 mm
0554 0660Control and adjustment set for Testo humidity probes, salt solution with 11.3% RH and 75.3% RH, incl. adapter for
0430 0145Cable, 5 m long, connects probe with plug-in head to measuring instrument, PUR coating material
0600 1693Adapter to connect NiCr-Ni thermocouples and probes with open wire ends
0554 0004Silicone heat paste (14g), Tmax = +260°C, improves heat transfer in surface probes
0363 1712Spare measuring tip for smelting probe
0554 0636testo saline solution pot for checking humidity probes, 33 %RH
0520 0006ISO calibration certificate humidity
0520 0013ISO calibration certificate/humidity
0520 0083ISO calibration certificate/humidity
0520 0206DAkkS calibration certificate/humidity
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testo 645
Probes
Probe type
Dimensions
Probe shaft/probe shaft tip
Type K (NiCr-Ni)
Quick-action surface probe, Plug-in
head. connection cable 0430 0143
or 0430 0145 required
Super quick-action immersion/
penetration probe for
measurements in liquids , Plug-in
head. connection cable 0430 0143
150 mm
Ø 10 mm
150 mm
Ø 1.5 mm
or 0430 0145 required
Super quick-action immersion/
penetration probe for high
temperatures , Plug-in head.
connection cable 0430 0143 or
470 mm
Ø 1.5 mm
0430 0145 required
Spare meas. head for pipe wrap
35 mm
probe, TC Type K
15 mm
1) According to norm EN 60751, the accuracy of Classes 1 / 2 refers to -40 to +1000/+1200 °C.
Pt100
Highly accurate immersion/
penetration probe , Plug-in head.
connection cable 0430 0143 or
0430 0145 required
200 mm
Ø 3 mm
Measuring
Accuracy
range
-200 to +300 °C
-200 to +600 °C
-200 to
+1100 °C
-60 to +130 °C Class 2
-100 to +350 °C
Class 2
Class 1
Class 1
±(0.06 °C +0.1% of m.v.) 30 s
t
99
1)
1)
1)
1)
3 s
1 s
1 s
5 s
Part no.
0604 0194
0604 0493
0604 0593
0602 0092
0628 0015
Flexible precision immersion probe,
cable heat-proof up to +300°C ,
Plug-in head. connection cable
0430 0143 or 0430 0145 required
1000 mm 50 mm
Ø 3.5 mm Ø 6 mm
Humidity probes
Standard ambient air probe up to
+70°C, Plug-in head. connection
cable 0430 0143 or 0430 0145
required
Thin humidity probe incl. 4
attachable protection caps for
ambient air measurements,
measurements in exhaust air
Ø 12 mm
250 mm
Ø 4 mm
ducts and equilibrium moisture
measurements , Plug-in head.
connection cable 0430 0143 or
0430 0145 required
Highly accurate reference humidity/
temp. probe, Plug-in head.
connection cable 0430 0143 or
0430 0145 required
Humidity/temperature probe ,
Plug-in head. connection cable
0430 0143 or 0430 0145 required
2) According to standard EN 60751, the accuracy of Class A and B refer to -200 to +600 °C.
Ø 21 mm
Ø 21 mm
-100 to +265 °C
0 to +100 %RH
-20 to +70 °C
0 to +100 %RH
-20 to +70 °C
0 to +100 %RH
-20 to +70 °C
0... +100 %RH
-20 to +70 °C
±(0.06 °C +0.1% of m.v.)
±2 %RH (+2 to +98 %RH)
±0.4 °C (-10 to +50 °C)
±0.5 °C (remaining range)
±2 %RH (+2 to +98 %RH)
±0.4 °C (-10 to +50 °C)
±0.5 °C (-20 to -10.1 °C)
±0.5 °C (+50.1 to +70 °C)
±1 %RH (+10 to +90 %RH)*
±2 %RH (remaining range)
* in the temperature range from
+15°C to +30°C
±0.2 °C (+10 to +40 °C)
±0.4 °C (remaining range)
±2 %RH (+2... +98 %RH)
±0.4 °C (+0.1 to +50 °C)
±0.5 °C (-20 to 0 °C)
±0.5 °C (+50.1 to +70 °C)
80 s
12 s
15 s
12 s
12 s
0628 0016
0636 9740
0636 2130
0636 9741
0636 9742
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testo 645
Probes
Probe type
Probes Process humidity
Standard pressure dewpoint probe
for measurements in compressed
air systems , Plug-in head.
connection cable 0430 0143 or
0430 0145 required
Precision pressure dewpoint probe
for measurements in compressed
air systems incl. cert. with test
point -40°C tpd, Plug-in head.
connection cable 0430 0143 or
0430 0145 required
High humidity level probe w/
heated sensor element, no
humidity on sensor, Plug-in head.
connection cable 0430 0143 or
0430 0145 required
Robust high temperature/humidity
probe up to +180°C , Plug-in head.
connection cable 0430 0143 or
0430 0145 required
Flexible humidity probe (does not
retain shape) for measurements in
inaccessible places , Plug-in head.
connection cable 0430 0143 or
0430 0145 required
Dimensions
Probe shaft/probe shaft tip
300 mm
300 mm
300 mm
Ø 12 mm
300 mm
Ø 12 mm
1500 mm 100 mm
Ø 12 mm
Measuring
range
0 to +100 %RH
-20 to
+50 °C tpd
0 to +100 %RH
-40 to
+50 °C tpd
0 to +100 %RH
-20 to +85 °C
0 to +100 %RH
-20 to +180 °C
0 to +100 %RH
-20 to +180 °C
Accuracy
±0.9 °C tpd (+5 to +50 °C tpd)
±1 °C tpd (0 to +4.9 °C tpd)
±2 °C tpd (-5 to -0.1 °C tpd)
±3 °C tpd (-10 to -5.1 °C tpd)
±4 °C tpd (-20 to -10.1 °C tpd)
±0.8 °C tpd (-4.9 to +50 °C tpd)
±1 °C tpd (-9.9 to -5 °C tpd)
±2 °C tpd (-19.9 to -10 °C tpd)
±3 °C tpd (-29.9 to -20 °C tpd)
±4 °C tpd (-40 to -30 °C tpd)
±2.5 %RH (0 to +100 %RH)
±0.4 °C (-10 to +50 °C)
±0.5 °C (-20 to -10.1 °C)
±0.5 °C (+50.1 to +100 °C)
* in the temperature range from
+10°C to +30°C
±2 %RH (+2 to +98 %RH)
±0.4 °C (+0.1 to +50 °C)
±0.5 °C (remaining range)
±2 %RH (+2 to +98 %RH)
±0.4 °C (+0.1 to +50 °C)
±0.5 °C (-20 to 0 °C)
±0.5 °C (+50.1 to +180 °C)
t
99
30 s
30 s
30 s
Part no.
0636 9840
0636 9841
0636 2142
0628 0021
0628 0022
Probes Material and equilibrium moisture
Robust humidity probe e.g. for
measuring equilibrium moisture
or for measurements in exhaust
ducts to +120°C, Plug-in head.
connection cable 0430 0143 or
0430 0145 required
Probes aw value
aw value set: pressure-tight
precision humidity probe with
certificate, measurement chamber
and 5 sample bowls (plastic),
Reproducibility of aw value ±0.003
300 mm
Ø 12 mm
0 to +100 %RH
-20 to +120 °C
0 to +1 aW
0 to +100 %RH
-20 to +70 °C
±2 %RH (+2 to +98 %RH)
±0.4 °C (-10 to +50 °C)
±0.5 °C (remaining range)
±0.01 aW (+0.1 to +0.9 aW)
±0.02 aW (+0.9 to +1 aW)
±1 %RH (+10 to +90 %RH)
±2 %RH (0 to +10 %RH)
±2 %RH (+90 to +100 %RH)
±0.4 °C (-10 to +50 °C)
±0.5 °C (remaining range)
30 s
0636 2140
0628 0024
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testo 645
Covering caps
Caps for humidity probes Ø 12m and 21mm
Metal protection cage, Ø 12 mm for humidity probes, for measurement in
flow velocities of less than 10 m/s
Cap with wire mesh filter, Ø 12 mm
PTFE sintered filter, Ø 21 mm, for corrosive substances, high humidity
range (long-term measurements), high velocities
Sintered PTFE filter, Ø 12 mm, for corrosive media, High humidity range
(long-term measurements), high flow velocities.
PTFE sintered filter, Ø 12 mm, for corrosive substances, high humidity
range (non-stop measurements), high flow speeds
Stainless steel sintered cap, Ø 21 mm, can be screwed onto humidity
probe, protection in case of high mechanical load and high velocities
Stainless steel sintered filter, pore size 100 µm, probe protection in dusty
atmospheres or higher flow velocities, for measurements at higher flow
velocities or in contaminated air
Illustration
Ø 12 mm
Ø 21 mm
Ø 12 mm
Ø 12 mm
Ø 21 mm
Ø 12 mm
For humidity probes
0636 9740, 0636 9715
All humidity probes with Ø
12 mm
All humidity probes with Ø
21 mm
0636 9769, 0636 9740, 0636
9715
0628 0021, 0628 0022, 0636
2140, 0636 2142
All humidity probes Ø 21 mm
0636 9740, 0636 9715
Part no.
0554 0755
0554 0757
0554 0666
0554 0756
0554 0758
0554 0640
0554 0641
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testo 645
0981 9634/msp/I/01.2019
www.testo.com
Subject to change without notice.
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