Precision chilled mirror for pressure dew point

MBW 973

pressure dew point up to 20 Bar
laboratory reference
high precision
fast response

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Precision dew point measurements at up to 20 Bar.

Model MBW 973 provides a fundamental dew point measurement. The 973 gives the user an intuitive touch screen interface, allowing easy monitoring of key measurement parameters and system health. The mirror check facility allows the user to vaporise accumulated condensates without having to disassemble the instrument.

Optimum Response Injection System (ORIS)

The ORIS is a feature unique to MBW chilled mirror devices. This pre-programmed vapour injection system accelerates stabilisation times when measuring at low dew point levels. A layer of frost is built on the mirror to rapidly achieve an equilibrium point where the rate of sublimation and condensation are equal.

 A graph showing the improvement in stabilisation time when using ORIS

ForcefrostTM function

Below 0 °C water may condense as either liquid or solid. This is a particular problem when working at dew points just below 0 °C, and can cause up to a 3 °C difference in condensation temperature. For correct calculation of relative humidity (rh), the phase of the condensate must be known.  When the Forcefrost function is activated at a user defined temperature the mirror over-cools to ensure that a frost is formed when below 0 °C, and to remove the uncertainty. 

Frost MBW973


MBW973 pressure sensor

Pressure Sensor

Integrated pressure measurement in the 973 means that calculation of ppmv can be performed accurately. As the 973 can be used as a calibration device, other devices under calibration can be corrected for pressure dew point calculation.

MBW973 temperature probe

PRT Temperature Probe

The 973 is supplied with a 4-wire PT100 Platinum Resistance thermometer (PRT). This allows precise temperature measurement for the calculation of relative humidity.

Range: -50 to +100 °C

Ø2 x 100 mm PRT on 3m cable

Transit case for MBW 473

Transit Case

Each 973 is supplied with a robust IP65 transit case for safe transportation to site for calibration projects.


Measuring range

Frost/Dew point

-60 to +20 °C


-50 to +100 °C

Relative humidity

0.1 to 100 %rh

Humidity content by volume

100 to 20,000 ppm

Humidity content by weight

5 to 2,500 ppm


Frost/Dew point

≤ ± 0.1 °C (-60 to +20 °C), ± 0.3 °C


≤ ± 0.1 °C

Relative humidity

≤ ± 0.5 %rh


≤ ± 0.1 % range


Frost/Dew Point

≤ ± 0.05 °C


≤ ± 0.05 °C

Standard Features


Rhodium plated gold

Temperature sensor

Ø2 x 100 mm PRT on 3 m cable

Digital I/O


Thermoelectric mirror cooling

3-stage with 80 °C depression at 20 °C ambient

Mirror temperature sensors

RTD (Pt100)


5.7 " LCD with touch screen

Internal gas tubes

Stainless steel 316L (Inlet and Outlet) FEP outlet with sample pump

Gas connections

6 mm or 1/4 " Swagelok fittings


Optimum Response Injection System

Power cable


Operating instructions

English and German

Calibration certificate

Factory calibration: 5 points FP/DP, 3 points temperature. Upgrade to SCS accredited ISO17025 calibration available

Optional Features

High pressure

10 or 20 bar internal pressure sensor (no sample pump fitted)

Analogue outputs

User programmable, 2 x 4 to 20 mA or 0 to 10 V

Additional water cooling

Extends frost/dew point range to -70 °C (water temp. 5 °C, ambient 20 °C)

Transport case

Custom fit foam lined Pelicase

Additional Information


Air, additional water cooling optional

Operating conditions

-20 to +40 °C, maximum 98 %rh non-condensing

Storage conditions

-20 to +50 °C


In Transport Case


420 mm

650 mm


155 mm

370 mm


390 mm

510 mm


12 kg

26 kg



100 to 120 VAC / 200 to 240 VAC, 50/60 Hz (auto switching)

Power consumption

200 Watt

All specifications subject to change