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Fluke Calibration 1620A Digital Thermometer-Hygrometer
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Personal Greeting

The Fluke 1620A (DewK) thermo hygrometer and humidity monitor measures temperature to ± 0.125 °C and humidity to ± 1.5 % on two channels, and displays it on a big, clear screen. Ethernet, or RS-232 will allow you to network as many Fluke 1620s (DewKs) as you’d like. And the LogWare III software will allow real-time logging of multiple Fluke 1620s (DewKs), data storage to your computer and seamless integration with MET/CAL® software.

  • Superior accuracy
  • Network enabled
  • Powerful logging and analysis tools
  • Two interchangeable calibrated sensors
  • Huge memory
  • Upgraded software

Two types of sensors are available.

The high-accuracy sensor (“H model) reads temperature to ± 0.125 °C over a calibrated range of 16 °C to 24 °C. Relative humidity readings are to ± 1.5 % RH from 20 % RH to 70 % RH.

The standard-accuracy sensor (“S model) reads temperature to ± 0.25 °C over its calibrated range of 15 °C to 35 °C. Relative humidity readings are to ± 2 % RH from 20 % RH to 70 % RH.

All Fluke 1620A (DewK) thermo-hygrometer sensors come with NVLAP accredited certificates of calibration for both temperature and humidity, complete with data and NIST traceability.

Ethernet capability

With its built-in Ethernet RJ45 jack, multiple Fluke 1620A (DewK) thermo hygrometers can be monitored from the same screen using LogWare III client-server software. Ethernet also gives you the possibility for remote connectivity over the internet, so you can monitor critical conditions while you’re away.

If you need a printout, send data to a printer through the RS-232 interface in real time.

Math and statistical functions

In addition to temperature and humidity, the DewK calculates dew point, heat index, and rates of change for both temperature and humidity. Min, max, and a variety of other statistics are also calculated and can be shown on-screen. Daily summary statistics, including min, max, and maximum rates of change are stored for the most recent sixty days.

Calibrated sensors

With inputs for two sensors, each measuring both temperature and relative humidity, one Fluke 1620 (DewK)can monitor two locations at the same time. Both sensors can be run via extension cables to remote locations up to 100 feet away, or one sensor can be directly mounted to the top of the DewK.

Each sensor is calibrated for both temperature and humidity by Fluke Calibration. The calibration constants assigned to the sensors reside in a memory chip located inside the sensor housing, so sensors may be used interchangeably between different Fluke 1620 (DewKs), and the recalibration of sensors doesn’t require an accompanying Fluke 1620 (DewK).

Sensors may also be assigned a unique identifier (up to 16 characters) to facilitate record keeping by matching the sensor identifier with the collected data. Each DewK ships with one sensor, with additional sensors available from Fluke Calibration. Spare sensors may also be purchased as a kit, which includes a wall mounting bracket and a 25-foot extension cable.


The DewK thermo hygrometer and humidity monitor has enough on-board memory to store up to 400,000 date- and times stamped data points. That’s two years’ worth of data for both measurements from two sensors if readings are taken every ten minutes!

Alarms and battery backup

Alarm settings can be set up quickly in the Fluke 1620 (DewK)based on temperature, the rate of change in temperature, RH, the rate of change in RH, and instrument fault conditions. Alarms can be both visual (flashing display) and audible (beeping). Likewise, alarm settings can be set up and events triggered in LogWare III. The Fluke 1620 (DewK)is also equipped with a 0 to 12 volt alarm output that can trigger a process control system.

A backup battery shuts down the Fluke 1620 (DewKs)display but maintains measurements for up to 16 hours in the event of a power failure.

Large, easy-to-read display

Want to view data from across the room? Want to view data from two temperature and two humidity inputs simultaneously? Want to view data graphically, statistically, or both? At the same time?! The Fluke 1620 (DewKs)thermo hygrometer and humidity monitor does everything you could want—or at least everything we could think of. Up to sixteen different display setups can be stored and recalled at the touch of a single button. And all 16 can be easily modified, so you get exactly what you want.

Operating Range
   0 °C to 50 °C (32 °F to 122 °F); 0 % RH to 100 % RH
Calibrated Temperature Accuracy (“H” Model)
   ± 0.125 °C from 16 °C to 24 °C
   (± 0.225 °F from 60.8 °F to 75.2 °F)
Calibrated temperature Accuracy (“S” Model)
   ± 0.25 °C from 15 °C to 35 °C
   (± 0.45 °F from 59 °F to 95 °F)
Calibrated RH Accuracy (“H” Model)
   ± 1.5 % RH from 20 % RH to 70 % RH
Calibrated RH Accuracy (“S” Model)
   ± 2 % RH from 20 % RH to 70 % RH
Expected Extrapolated Performance (Uncertified)
   ± 0.5 °C (± 0.9 °F) outside calibrated range
   ± 3 % RH outside calibrated range
Delta Temperature Accuracy
   ± 0.025 °C for ± 1 ° changes within 15 °C to 35 °C
   (± 0.045 °F for ± 1 ° changes within 59 °F to 95 °F)
Temperature Resolution
   User selectable up to 0.001 °C/°F on front-panel display (0.01° recorded)
Delta Humidity Accuracy
   ± 1.0 % RH for ± 5 % changes within 20 % RH to 70 % RH
RH Resolution
   User selectable up to 0.01 % on front-panel display (0.1 % recorded)
   Up to two sensors, measure temperature and relative humidity, detachable, cable-extendable, interchangeable, self-contained calibrations, may be assigned unique 16-character identifications
   240 x 128 graphics monochrome LCD, displays password-protected temperature/humidity data graphically, numerically, and statistically (one or both channels); 16 pre-defined, user-changeable screen setups
   400,000 typical individual date/time-stamped readings
   Password-protected visual, audible, and external alarms for temperature, temperature rate, RH, RH rate, and fault conditions
Alarm Port Output
   2.5 mm two-conductor subminiature plug, 0 V normal, 11 to 12 V active, sources up to 20 mA
   RJ45 jack, 10 Base-T or 100 Base-TX; static or dynamic (DHCP client) IP address assignment
Web Page
   Embedded web page interface features: instrument identification, measurements, password-protected terminal page; can be disabled
Wireless Option
   Requires wireless modem. 802.15.4 (underlies Zigbee), 2.4 GHz frequency, 1 mW transmit power, 30 m (100 ft) typical unobstructed range; can be disabled
   Wall mounted (hardware included) or set on a bench top
   12 V dc from external 100 to 240 V dc power supply
Battery Backup
   Standard 9 V battery enables continued measuring during power disruptions
Size (DewK) ( HxWxD )
   125 mm x 211 mm x 51 mm (4.9 x 8.3 x 2.0 in)
Size (Sensors) ( LxDia )
   79 mm x 19 mm (3.1 x 0.75 in)
   0.7 kg (1.5 lb)
   Certificate of NIST-traceable NVLAP accredited temperature and humidity calibration included; As Found and As Left data supplied at three temperature points and three humidity points each at 20 °C (68 °F); Complies with NCSL/ISO/IEC 17025:2000 and ANSI/NCSL Z540-1-1994
LogWare III (Optional Software)
   Requirements include: Microsoft® Windows® 2000 (SP4) or XP (SP2) operating system, IBM compatible Intel Pentium® IV 1 GHz PC processor or better, 512 Mb RAM (1Gb or more recommended), 200 Mb HDD space for installation (additional free space recommended for data storage), CD-ROM drive for installation
Model Name Description

The “DewK” Thermo-Hygrometer, Standard-Accuracy

  • One standard-accuracy sensor
  • Wall mount bracket
  • RS-232 cable

The “DewK” Thermo-Hygrometer, Standard-Accuracy Value Kit

  • 1620A-S Thermo-Hygrometer, Standard-Accuracy
  • 2627-S Spare Sensor Kit
  • 9936A LogWare III Software, Single License

The “DewK” Thermo-Hygrometer, High-Accuracy

  • One high-accuracy sensor
  • Wall mount bracket
  • RS-232 cable

The “DewK” Thermo-Hygrometer, High-Accuracy Value Kit

  • 1620A-H Thermo-Hygrometer, High-Accuracy
  • 2627-H Spare Sensor Kit
  • 9936A LogWare III Software, Single License

LogWare III Software, Single License


Additional 1-Pack License for LogWare III Software
(Additional licenses require the purchase and installation of 9936A LogWare III Software (single license))


Additional 5-Pack Licenses for LogWare III Software
(Additional licenses require the purchase and installation of 9936A LogWare III Software (single license))


Additional 10-Pack Licenses for LogWare III Software
(Additional licenses require the purchase and installation of 9936A LogWare III Software (single license))


Additional Site License for LogWare III Software
(Additional licenses require the purchase and installation of 9936A LogWare III Software (single license))

Accessories common to all models:

Accessory Description

Spare Power Supply, 100 to 240 V ac


Protective Case for 1620A and two sensors


Spare Sensor, standard-accuracy


Spare sensor, High-Accuracy


Spare Sensor Kit with Standard-Accuracy Sensor


Spare Sensor Kit with High-Accuracy Sensor


Cable, Sensor Extension, 7.6 m (25 ft)


Cable, Sensor Extension, 15.2 m (50 ft)

Priority Gold Instrument CarePlan

Fluke Calibration Priority Gold Instrument CarePlans are available for most calibration products. 

Silver CarePlan

Fluke Calibration Silver CarePlans are available for most calibration products.