Fluke Calibration 1620A-H-156
DewK Thermo-Hygrometer, High Accuracy

  • High accuracy
  • Network enabled
  • Powerful logging and analysis tools
  • One calibrated sensor
  • Huge memory
  • Upgraded software
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Product Information
Datasheet 206 KB PDF
Manual 2.38 MB PDF
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The Fluke MET/CAL compatible 1620A DewK Thermo-Hygrometer revolutionizes environmental monitoring for calibration laboratories.Now you can easily monitor and record conditions through-out your entire facility with the Hart Calibration 1620A DewK’s new Ethernet and wire-less connections, and set your upgraded LogWare III software to notify you immediately of changing conditions.

You’ll still have the superior convenience, dependability, and NIST-traceable accuracy of a Fluke Hart Calibration 1620, but your Fluke Calibration 1620A will give you the added accessibility and peace of mind you’ve been looking for.


The high-accuracy sensor ("1620A-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.

All DewK sensors come with NVLAP accredited certificates of calibration for both temperature and humidity, complete with data and NIST traceability. Hart provides exceptional uncertainties, including total test uncertainty ratios better than 3:1 for both temperature and relative humidity-even for the high-accuracy sensors!

Both sensors can also measure temperature below their respective calibrated ranges to 0°C and above their respective calibrated ranges to 50°C with typical accuracy of ± 0.5°C. And RH readings from 0 %RH to 20 %RH and from 70 %RH to 100 %RH are typically within ± 3 %.

Ethernet and wireless capability

The DewK gives you all the communications options you expect, and then some. With its built-in Ethernet RJ45 jack, multiple DewKs can be monitored from the same screen using Hart's new 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.

Cables running along the floor can be a safety hazard, and cables hanging from the ceiling and walls are an eyesore. With the DewK, your wireless dreams will come true when you connect your computer through an RF modem up to 100 ft away, without the clutter of all the extra cables!

Finally, 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, without the need to buy additional software. 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 the DewK you get two for the price of one. Having inputs for two sensors, each measuring both temperature and relative humidity, one 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 at Fluke's Fluke Calibration Division. 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 DewKs, and the recalibration of sensors doesn't require an accompanying 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 Hart. Spare sensors may also be purchased as a kit, which includes a case for the sensor, a wall mounting bracket, and a 25-foot extension cable.


The DewK has enough on-board memory to store up to 400,000 date- and time-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 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 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 DewK's display but maintains measurements for up to 16 hours in the event of a power failure.

One very cool 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 DewK does everything you could want.  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.

The DewK lets you view data just about any way you like it. Both graphical data and statistical data can be shown for temperature and humidity from one or two inputs. Modifying any of the standard screens is easily done, so you see exactly what you want-no more, no less.


Fluke's Fluke Calibration Division supplies the world's finest measurement laboratories with world-class temperature standards. Hart not only measures temperature and humidity better than anybody, they make temperature measurements functional and productive. Don't compromise on your lab standards. Measure with confidence. Partner with Hart Scientific.

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)
Inputs Up to two sensors, measure temperature and relative humidity, detachable, cable-extendable, interchangeable, self-contained calibrations, may be assigned unique 16-character identifications
Display 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
Memory 400,000 typical individual date/time-stamped readings
Alarms 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
Connectivity Ethernet, RS-232, RF (optional)
Ethernet 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
Mounting Wall mounted (hardware included) or set on a bench top
Power 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)
Weight 0.7 kg (1.5 lb)
Calibration 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
Ordering Information
Model Description Buy Online Price
MFR ID: 2723978
Fluke Calibration 1620A-H-156 DewK Thermo Hygrometer, High Accuracy Buy Now $2,925.00
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Included Accessories
  • 1 - High-accuracy sensor
  • 1 - Wall mount bracket
  • 1 - RS-232 cable
  • 1 - User's Manual
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