6331/7321/7341/7381 Deep-Well Compact Baths




Product Description

Need a bath with a lot of immersion depth, great stability, and a low price tag? How about one that minimizes fluid costs, changes temperatures quickly, and runs quietly?

Fluke Calibration’s new Deep-Well Compact Bath series features four models covering temperatures from –80 °C to 300 °C.

Each model includes a 457 mm (18-inch) deep tank to accommodate long-stem PRTs, SPRTs, and liquid-in-glass (LIG) thermometers. Access openings are 120 by 172 mm (4.7 in by 6.8 in) so you can calibrate many thermometers simultaneously. Yet only 15.9 liters (4.2 gallons) of fluid are needed to get all the benefits Deep-Well Compact Baths offer.

Using our own best-in-class temperature controller, these baths deliver the performance you need for confidence in your calibrations. The 7381 (–80 °C to 110 °C) features both stability and uniformity better than ±0.007 °C over its entire range. The 7341 and 7321 (–45 °C to 150 °C and –20 °C to 150 °C, respectively) are stable to ±0.005 °C and uniform to ±0.007 °C at temperatures below ambient. And finally, the 6331 provides stability and uniformity from ±0.007 °C to ±0.025 °C over its range from 40 °C to 300 °C.

Be sure to understand the performance of the temperature calibration equipment you buy. Some manufacturers offer only limited (and often difficult to interpret) specifications. The specifications tab includes stability and uniformity values for the entire range of each bath—and tells you what fluid we used in the measurements. If that’s still not enough, give us a call and we’ll be happy to explain anything—and share data with you.

Fluke Calibration’s control system automatically adds refrigeration when you need to cool down quickly, and shuts down refrigeration when you need to heat up quickly. For maximum stability, refrigeration levels are automatically balanced to match the set-point temperature you’re working at.

Connect any of these baths to a Fluke Calibration thermometer readout and our industry-leading MET/TEMP II temperature calibration software, and you’ll be performing automated probe calibrations within minutes from switch-on.

Want to optimize your bath for calibrating liquid-in-glass thermometers? Simple. With the optional LIG Thermometer Calibration Kit, you get an easy-to-install fluid level adapter tube that raises the meniscus of the bath fluid to within about 12 mm (0.5 in) of the top surface of the bath itself. The kit also includes a thermometer carousel that fits onto the top of the fluid level adapter tube and holds up to ten LIG thermometers in place. A magnifying scope (8X) is also available that mounts to the front of any Deep-Well Compact Bath so you can clearly see the liquid level of your thermometer against its temperature scale.

Like all Fluke Calibration baths, these units come with a report of test that includes one hour of stability data and a verification of set-point accuracy. A convenient overflow reservoir captures any excess fluid resulting from fluid expansion, allowing the trapped fluid to be reused following subsequent fluid contraction. A drain is also provided for easily emptying the bath’s tank when needed.


Ample immersion depth and great stability, in a high value compact bath

  • 457 mm (18 in) of depth with just 15.9 liters (4.2 gal) of fluid
  • Perfect for liquid-in-glass thermometers with optional LIG kit
  • Fast, quiet, compact (yet deep!), and economical

Find high temperature baths (300 °C) and refrigerated baths for low temperature calibration (–80 °C), in compact packages, and with deep immersion from Fluke Calibration our metrology baths are well known world-wide for excellent temperature control that maintains excellent temperature stability (±0.005 °C) and uniformity (±0.007 °C).


6331  35 °C to 300 °C
7321  –20 °C to 150 °C
7341  –45 °C to 150 °C
7381  –80 °C to 110 °C
6331 ±0.007 °C at 100 °C (oil 5012)
±0.010 °C at 200 °C (oil 5017)
±0.015 °C at 300 °C (oil 5017)
7321 ±0.005°C at –20°C (ethanol)
±0.005°C at 25°C (water)
±0.007°C at 150°C (oil 5012)
7341  ±0.005°C at –45°C (ethanol)
±0.005°C at 25°C (water)
±0.007°C at 150°C (oil 5012)
7381 ±0.006°C at –80°C (ethanol)
±0.005°C at 0°C (ethanol)
±0.005°C at 100°C (oil 5012)
6331 ±0.007 °C at 100 °C (oil 5012)
±0.017 °C at 200 °C (oil 5017)
±0.025 °C at 300 °C (oil 5017)
7321 ±0.007 °C at –20 °C (ethanol)
±0.00 7 °C at 2 5°C (water)
±0.010°C at 150 °C (oil 5012)
7341 ±0.007 °C at –45 °C (ethanol)
±0.007 °C at 25 °C (water)
±0.010 °C at 150 °C (oil 5012)
7381 ±0.007 °C at –80 °C (ethanol)
±0.007 °C at 0 °C (ethanol)
±0.007 °C at 100 °C (oil 5012)
Heating Time†
6331  130 minutes, from 40 °C to 300 °C (oil 5017)
7321  120 minutes, from 25 °C to 150 °C (oil 5012)
7341  120 minutes, from 25 °C to 150 °C (oil 5012)
7381  60 minutes, from 25 °C to 100 °C (oil 5012)
Cooling Time†
6331  14 hours, from 300 °C to 100 °C (oil 5017)
7321  110 minutes, from 25 °C to –20 °C (ethanol)
7341  130 minutes, from 25°C to –45°C (ethanol)
7381  210 minutes, from 25 °C to –80 °C (ethanol)
Stabilization Time 15–20 minute
Temperature Setting Digital display with push-button data entry
Set-Point Resolution 0.01°; 0.00018° in high-resolution mode
Display Resolution 0.01
Digital Setting Accuracy ±1°C
Digital Setting Repeatability ±0.01°C
Access Opening 120 x 172 mm (4.7 x 6.8 in)
Depth 457 mm (18 in) without Liquid-in-Glass Thermometer Cal Kit

482 mm (19 in) with Liquid-in-Glass Thermometer Cal Kit

Wetted Parts 304 stainless steel
6331 115 VAC (±10 %), 50/60 Hz, 14.8 A or
230 VAC (±10 %), 50/60 Hz, 7.4 A, specify
7321 115 VAC (±10 %), 60 Hz, 14 A or
230 VAC (±10 %), 50 Hz, 7 A, specify
7341 115 VAC (±10 %), 60 Hz, 16 A or
230 VAC (±10 %), 50 Hz, 8 A, specify
7381 230 VAC (±10 %), 50 or 60 Hz, specify, 10 A
Volume 15.9 liters (4.2 gal)
Size (HxWxD) 1067 x 356 x 788 mm (940 mm from floor to tank access opening) [42 x 14 x 31 in (37 in from floor to tank access opening)]
6331  41 kg (90 lb.)
7321  62 kg (137 lb.)
7341  68 kg (150 lb.)
7381  91 kg (200 lb.)
Automation Use the 1586A Super-DAQ to automate temperature sensor calibration
  †Rated at nominal 115 V (or optional 230 V)

Models and Accessories

Model Name Description
6331 Deep-Well Compact Bath, 40 °C to 300 °C
7321 Deep-Well Compact Bath, –20 °C to 150 °C
7341 Deep-Well Compact Bath, –45 °C to 150 °C
7381 Deep-Well Compact Bath, –80 °C to 110 °C

Accessories common to all models  :

Accessory Description
Calibration Bath Fluids Full line of bath fluids
2019-DCB Fluid Level Adapter Fluid Level Adapter
2069 Magnifying Scope 8X Magnifying Scope, with Mounts
2001-IEEE IEEE-488 Interface
2012-DCB Spare Access Cover, Plastic, 7321, 7341, 7381
2020-6331 Spare Access Cover, Stainless Steel, 6331
2027-DCBW TPW Holding Fixture (7321, 7341, 7381)
2027-DCBM Mercury TP Holding Fixture (7341)
2020-6331 Spare Access Cover, Stainless Steel, 6331
Silver CarePlan Fluke Calibration Silver CarePlans are available for most calibration products. Please contact your local Fluke Calibration sales representative for details or to request a quote.

About us

บริษัท เมสเชอร์เมนท์เอเชีย จำกัด
Measurementasia Co.,Ltd.

99 Moo. 3, Khlong 5, Khlong Luang,
Pathumthani 12120



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