When Humidity Accuracy Matters, Measure It Directly.
Critical humidity measurements require more than a stable sensor. They require a measurement you can trust as a reference.
The MBW CALIBRATION™ Model 373™ Chilled Mirror Hygrometer provides high-precision, direct measurement of dew point and frost point for calibration laboratories, National Metrology Institutes, research facilities, and demanding industrial applications.
With a measurement capability extending to −95°C frost point and +95°C dew point depending on configuration, dual platinum resistance thermometers (PRTs), temperature-controlled sampling, and a removable mirror module, the Model 373 is designed for applications requiring exceptional measurement stability, repeatability, and traceability.
Talk to a Humidity Measurement Expert
What Is the MBW Model 373?
The MBW Model 373 is a high-precision reference chilled mirror hygrometer used to directly measure dew point and frost point temperature. It is designed for humidity calibration, transfer-standard measurements, metrology laboratories, research, trace humidity measurement, and critical process monitoring.
Unlike humidity sensors that infer moisture from an electrical response, chilled mirror hygrometry determines the temperature at which condensation forms on a temperature-controlled mirror. This direct measurement principle provides excellent repeatability, low drift, and long-term measurement stability.
- Wide measuring range -95 to +95 ̊C frost/dew point
- Dual mirror temperature sensors
- Removable mirror module for calibration in liquid
- Heated measuring heads and sampling systems
- High pressures up to 20000 kPa
- Temperature controlled sampling system
- Fast response
- Touch screen full color LCD user interface
Key Specifications
- Frost/dew point range: -95 to +95 ̊C
- Sample gas inlet pressure range: 50 to 20000 kPa
- Temperature measurement: -50 to +100 ̊C
- Temperature measurement with T12: -200 to +250 ̊C
Calibration Services for Process Instruments: Best Practices and Standards
More Than a Humidity Analyzer. A Measurement Reference.
The Model 373 is designed for applications where the humidity measurement itself may be used to calibrate, validate, or verify other instruments.
Typical applications include:
- Calibration transfer standards
- National Metrology Institutes
- ISO/IEC 17025 calibration laboratories
- Humidity generator calibration
- Environmental and climatic chamber calibration
- Meteorological reference measurements
- Fundamental research
- Trace humidity measurement
- Critical process monitoring
- Fuel-cell research
Process Insights identifies calibration transfer standards, meteorology references, fundamental research, trace humidity measurement, critical process monitoring, and fuel-cell research as primary Model 373 application
INDUSTRIES
- Semiconductor manufacturing
- Pharmaceutical manufacturing:
- Petrochemical industry
- Power generation
- Environmental monitoring
- Laboratories
Services
- Service and Repair
- Calibration
- On Site Service, Repair and Calibration
- DAkkS Calibration Laboratory
- Calibration of non-MBW products
- Training
SALES | TRAINING INQUIRIES
AMERICAS: info.americas@process-insights.com
EMEAI (includes India): info.emeai@process-insights.com
APAC: info.apac@process-insights.com
CHINA: info.cn@process-insights.com
SERVICE | TECHNICAL INQUIRIES ONLY
| Feature | Customer Benefit |
|---|---|
| −95 to +95°C frost/dew point capability* | Broad reference humidity measurement |
| Dual mirror PRTs | Independent precision mirror-temperature measurement |
| Removable mirror module | Supports calibration in a liquid bath |
| Temperature-controlled sampling | Enables demanding high dew-point measurements |
| Heated measuring heads | Helps prevent condensation before measurement |
| Pressure capability up to 20,000 kPa* | Supports high-pressure gas applications |
| External temperature measurement | Enables additional humidity calculations |
| Full-color touchscreen | Simple instrument setup and operation |
| Fast response | Efficient calibration and measurement workflows |
Model 373 Measurement Performance
| Specification | Model 373 |
|---|---|
| Measurement Principle | Chilled mirror hygrometry |
| Frost / Dew Point Capability | Up to −95 to +95°C, configuration dependent |
| Calibrated Accuracy | ≤ ±0.1°C frost/dew point* |
| Frost / Dew Point Reproducibility | ≤ ±0.05°C* |
| Temperature Measurement | −50 to +100°C |
| Temperature with T12 | −200 to +250°C |
| Mirror Temperature Sensors | Dual Pt-100 PRT |
| Mirror Cooling | 3-stage Peltier thermoelectric |
| Sample Pressure | Configuration dependent; up to 20,000 kPa listed by Process Insights |
| Display | Color touchscreen |
The Model 373 is particularly suited to:
ISO/IEC 17025 Calibration Laboratories
Use the 373 as a reference or transfer standard for dew point and humidity calibration.
National Metrology Institutes
Support high-level humidity measurement and interlaboratory comparisons.
Humidity Instrument Manufacturers
Calibrate and verify humidity and dew-point sensors against a stable reference.
Research Laboratories
Measure humidity in experiments requiring high precision and long-term stability.
Meteorology Laboratories
Establish high-quality reference dew/frost-point measurements.
MBW chilled mirrors are used as transfer standards by National Metrology Institutes and accredited laboratories, while Process Insights operates its own DAkkS-accredited ISO/IEC 17025 humidity and temperature calibration laboratory.
The Model 373 uses dual platinum resistance thermometers (PRTs) to measure mirror temperature.
For standards laboratories, an external resistance bridge can independently measure mirror temperature, allowing the user to reduce dependence on the instrument’s internal measurement electronics.
Process Insights specifically identifies this architecture as a way to help reduce measurement uncertainty and maintain long-term stability even if measurement electronics change.
Key Customer Challenge
“How do I maintain confidence in my reference measurement over the long term?”
Model 373 Solution
Dual mirror PRTs provide an independent path for high-precision mirror-temperature measurement—an important advantage for laboratories where measurement uncertainty and long-term traceability matter.
Measurement Uncertainty
Customer Challenge – “Can I trust this measurement enough to use it as my reference?”
Calibration and metrology applications require more than repeatability. They require a defensible measurement chain with low uncertainty.
Model 373 Solution
The chilled mirror measurement principle, dual mirror PRT architecture, removable mirror module, and calibration capability make the Model 373 particularly suited to reference measurement applications.
Long-Term Measurement Stability
Customer Challenge – “Will my reference remain stable over years of laboratory use?”
Long-term drift creates uncertainty and increases calibration requirements.
Model 373 Solution
Direct chilled mirror measurement and precision platinum resistance thermometry provide excellent long-term measurement stability. Process Insights says MBW chilled mirror analyzers typically have a service life exceeding 15 years and are used by National Metrology Institutes and accredited laboratories worldwide.
Measuring Very Low Humidity
Customer Challenge – “Can one reference instrument cover very low frost points and high dew points?”
Humidity calibration laboratories often need to cover an exceptionally broad measurement range.
Model 373 Solution
Model 373 configurations extend to −95°C frost point and +95°C dew point, allowing one platform to address a wide range of reference humidity measurements.
High Dew-Point Samples
Customer Challenge – “How do we prevent condensation before the sample reaches the mirror?”
Model 373 Solution
Temperature-controlled sample handling and heated measurement-head configurations help maintain the sample path above its dew point.
Why Chilled Mirror Hygrometry?
Direct Humidity Measurement Instead of an Inferred Sensor Response
This should be a major educational section.
A chilled mirror hygrometer determines dew or frost point by directly detecting condensation on a temperature-controlled mirror.
The mirror is cooled until condensation forms. Its temperature is precisely measured using a platinum resistance thermometer, establishing the dew or frost point of the sample gas.
Because the measurement is based on a physical condensation temperature rather than an inferred sensor response, chilled mirror hygrometry is widely used for reference measurements, calibration, metrology, and demanding humidity applications. Process Insights notes that MBW chilled mirrors are used as transfer standards by National Metrology Institutes and accredited laboratories.
Key Advantages
Direct measurement
Measure the actual condensation temperature.
Low drift
Avoid many of the long-term drift characteristics associated with indirect humidity sensors.
High repeatability
Designed for demanding reference measurements.
Wide measurement range
Measure very low frost points through high dew points.
Long-term stability
Ideal for calibration and metrology applications.
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