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Ultra-stable Maintenance Bath for Water Triple Point Cells

Kambic Ultra-stable Maintenance Bath

The ultra-stable bath for maintaining Triple Point of Water cells is a state-of-the-art metrological device of exceptional performance. Thanks to homogeneity and stability in the mK range, the cells can be held and operated stably at the triple point.

Our maintenance bath enables the long-term use of water triple point cells and thus highly precise calibrations of temperature measuring instruments.


  • Unique “Vertical flow design (VFD)”
  • Uniformity and stability in the mK range
  • Fluid ensures perfect heat transfer
  • 500mm immersion depth
  • Cycling function

Find out more about the Maintenance Bath for Water Triple Points

22-liter Triple Point of Water maintenance bath (OB-22/2 TPW)
Temperature range -5 °C to +130 °C 
Temperature stability (°C) 

±0.002 °C at 0 °C
±0.005 °C at 20 °C
±0.002 C at 100 °C
Temperature uniformity (°C)  ±0.007 ºC at 0 ºC
Number of cells 1
Tank volume 22 Liters
50-liter Triple Point of Water maintenance bath (OB-50/2 TPW)
Temperature range -5 °C to +130 °C 
Temperature stability (°C) 

±0.002 C at 0 °C
±0.005 °C at 20 °C
±0.002 °C at 100 °C
Temperature uniformity (°C)  ±0.007 ºC at 0 ºC
Number of cells 4
Tank volume 50 Liters 
All performance data recorded using liquid KDC 200.05
All performance measurements performed under controlled environmental conditions (Tenvironment = 22 °C ±3 °C)!

Maintenance bath for triple point cells

Outstanding Metrological Properties and Features

A special dual-cylinder design with unique vertical flow over the entire working volume ensures outstanding and exceptional performance.

Upon request, the bath will be delivered with an accredited calibration certificate according to ISO / IEC 17025.

Reliability and safety

The maintenance bath is equipped with an over-temperature protection, an independent safety circuit to prevent frost damage and comprehensive high-performance thermal insulation. An air-cooled, compressor-based cooling system is also available. 

An overflow drain with catch vessel and fluid drain valve is neatly hidden behind the front cover panel. For maintenance purposes, the bath is accessible from all four sides.


The maintenance bath offers a touch-screen controller with a user-friendly interface, a wide range of adjustable parameters and USB, Ethernet or RS232 ports. Castor wheels with brakes allow the bath to be moved easily.

Clients in every sector of the industry rely on Calibration Baths of Kambic.

The Triple Point of Water

In thermodynamics, the triple point of a substance is present at a defined combination of temperature and pressure. Here, the solid, liquid and gas phases exist in thermodynamic equilibrium. In other words... the only point where all three phases (solid, liquid and vapor) can be in equilibrium is the triple point.

Our Triple Point of Water maintenance baths are high precision devices that can maintain a stable temperature at the triple point of water. With these maintenance baths you can operate up to four water triple point cells.

By international agreement, the triple point of water is determined as 0.01 °C at a partial vapor pressure of 6.1166 mbar. At that point it is possible to turn all substance into steam, water or ice by making infinitesimal changes in pressure and temperature. Even if the total pressure is well above the triple point of water, the system can still be brought to the triple point of water, provided that the partial pressure of the water vapor is 6.1166 mbar.

Phase diagram triple point of water

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