Skip to main content

Model 973-SF6  Dew Point Chilled Mirror Hygrometer

For the measurement of humidity, SF6 purity and SO2 concentration in SF6 gas

MODEL 973-SF6 Dew Point Chilled Mirror Hygrometer 

The MBW CALIBRATION™ MODEL 973-SF6Dew Point Chilled Mirror Hygrometer Analyzer is an advanced SF6 gas analyzer for the measurement of humidity, SF6 purity and SO2 concentration in SF6 gas insulated switchgears (GIS) and other high voltage equipment. With its internal gas containment and recovery system, the 973-SF6 provides a high quality and environmentally safe measurement solution within a single self-contained unit.  

Pure SF6 is the standard filling within GIS, but over time gas compartments become contaminated with water vapor (H2O) through permeation and by desorption from internal materials. Whilst water vapor and SF6 do not normally react with each other, in the presence of a high-energy discharge, hydrogen and oxygen disassociated from water vapor will react with the sulfur and fluorine from SF6 to form decomposition by-products. These include sulfur dioxide (SO2) and hydrofluoric acid (HF) that are corrosive to the internal components of gas compartments.  SF6 with low water vapor content (low humidity) significantly reduces the potential for formation of these corrosive compounds, which is why accurate and repeatable measurement data is an invaluable part of any GIS preventative maintenance program.

MBW has been serving the electrical power industry for over forty years, beginning when Sulfur Hexafluoride (SF₆) became widely adopted in gas-insulated switchgear systems developed in Switzerland, Germany, and France. We engineered specialized solutions to meet the demanding requirements of this application and continue to provide the industry with stable, cost-effective instruments for measuring SF₆ gas quality.

MBW was the first to offer SF₆ gas analyzers capable of capturing and returning the measured gas back to the compartment minimizing atmospheric release and supporting environmental responsibility. Our analyzers use a fundamental chilled mirror technique that requires no routine sensor replacement or frequent calibration, making them ideal for remote locations where equipment return is costly and time-consuming.

The 973-SF6 Dew Point Chilled Mirror Hygrometer Analyzer includes:

  • Transport Peli-Case 1620
  • Serial cable DB9 3m 1:1 male/female
  • RS-232 / USB adapter
  • USB stick with 973-SF6  Software and operation manuals
  • Power cable (country specific)
  • Hex key for SOmodule
  • Cotton swabs, sterile (10 pieces)
  • Operation Manual
  • Calibration Certificate
  • All accessories can also be ordered separately to replace damaged or missing components.

APPLICATIONS

  • Electrical power utilities
  • Gas insulated switchgear
  • SF6 gas manufacturers and suppliers

Key Specifications

  • Frost/dew Point range: -50…+20 °C
  • Volume SF6 range: 80…100%
  • Inlet pressure range: 120…1’000 kPa abs.
  • Frost/dew point accuracy: ± 0.5 °C
  • ppmv /ppmw accuracy: ± 1 ppm +6% of reading
  • Volume SF6 accuracy: ± 0.5%
  • Pressure accuracy: ± 3 kPa

SULFUR DIOXIDE (SO2)

Sulphur Dioxide is the most common decomposition by-product measured during SF6 gas quality analysis.  Unlike most other decomposition products, it is relatively unreactive once formed, so its concentration remains stable over time, so measurement results are more dependable as a condition assessment parameter.

Since 2012, all our 973-SF6 MODEL analyzers have been produced ‘SO2 ready’.  This means that SO2 measurement can be easily added during production, or at a later time by the user. Measurement is based on a replaceable electrochemical sensor cell fitted in the gas path close to the sample inlet connection.  0…100 or 0…500 ppm ranges are available.

SO2 measurement performance is influenced by several factors that in combination can lead to measurement errors.  For this reason, measurement accuracy is specified ≤ ±2 % of the measured value.  To meet this specification, all SO2 sensors for use with the 973-SF6 are individually calibrated in gravimetrically prepared SF6/SO2 gas mixtures at three points over their specified range:

  • 100ppmv range:  0, 10, 100 ppmv
  • 500ppmv range: 0, 100, 500 ppmv

SF6 COUPLINGS

DN8 Coupling Part no. 102983

SF6 coupling DN8 with quick coupling (Rectus)

973-SF6_Coupling_DN8-500x333
DN20 Coupling Part no. 102983

SF6 coupling DN20 with quick coupling (Rectus)

973-SF6_Coupling_DN20-500x333
DN6 Coupling Part no. 104041

SF6 coupling DN6 with quick coupling (Rectus)

973-SF6_Coupling_DN20-500x333
DN12 Coupling Part no. 103477

SF6 coupling DN12 with quick coupling (Rectus)

973-SF6_Coupling_DN20-500x333
DN7 Coupling Part no. 100903

Double coupling DN7 (male / female)

973-SF6_Coupling_DN20-500x333
90° angle Part no. 103410

90° angle with Rectus couplings

973-SF6_Coupling_DN20-500x333
To Top

OUR Dew Point Chilled Mirror Hygrometer Analyzer SOLUTIONS

MODEL 373™

MBW CALIBRATION™ Humidity & Temperature Reference Dew Point Chilled Mirror up to 125°C
Process Insights_mbw 373 chilled mirror hygrometer

MODEL 473™

MBW CALIBRATION™ Humidity & Temperature Reference Dew Point Chilled Mirror up to 125°C
Process Insights MBW Model 473-RP2-2020

MODEL 573™

MBW CALIBRATION™ Dew Point Chilled Mirror for Fixed Industrial Installations & Measures Above Ambient Temperature
Process Insights_MBW Model 573_chilled mirror hygrometer

T12 Thermometer

MBW CALIBRATION™ Multi-Channel Stable Platinum Resistance Thermometer (PRT)
Process Insights_mbw temperatur T12_instrument

TempControl™ Software

Mirror Temperature Software
Process Insights_mbw temperatur T12_instrument

GECKO R2™ Metrology Software

Mirror Software
Process Insights_mbw temperatur T12_instrument

MODEL 973™

MBW CALIBRATION™ Portable Instrument Equipped with Integral Measuring Head for Both Spot & Continuous Measurement of Dew/Frost Point in Air & Other Gases
Process Insights_MBW Model 973L_chilled mirror hygrometer

MODEL 973CA™

MBW CALIBRATION™ Dew Point Chilled Mirror Analyzer for On-site Measurement and Validation of Compressed Air and Other High-Pressure Systems
Process Insights_MBW_Model 973ca

MODEL 973L™

MBW CALIBRATION™ Dew Point Chilled Mirror Analyzer with Optimal Response Injection System for Fast Measurements

For low range specifications

Process Insights_MBW Model 973L_chilled mirror hygrometer

MODEL 973S™

MBW CALIBRATION™ Dew Point Chilled Mirror Analyzer with integrated sample pump, external temperature measurement and transport case.

Standard Version

Process Insights_MBW Model 973S_chilled mirror hygrometer

MODEL 973 SF6™

MBW CALIBRATION™ Dew Point Chilled Mirror for Humidity Measurement in SF6 & SO2 in Gas Insulated Switchgears (GIS)
Process Insights_MBW 973-SF6_instrument
To Top