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Hygrometer, Dewpoint Monitors
Kahn manufactures hygrometers (dewpoint measurement instruments) that measure moisture in compressed air and other gases at pressures from vacuum to 6000 psig and temperatures from -120°C to 90°C (-184°F to 194°F). Digital Hygrometers, hygrometers that also function as a dew point transmitter, and other types available. kahn hygrometers are often used on hydrogen generators.
Fluid Energy works with customers to supply the most cost-effective hygrometer technology. Hygrometers with ceramic sensors, aluminum oxide sensors, chilled mirror optical systems, and multi-channel process analyzer technology are available to meet the needs of the simplest to most complicated dewpoint measurement applications.
Kahn
Hygrometer applications
Cermax portable hygrometer
Cermet II hygrometer
Chilled Mirror Optical Hygrometers
Hygrometer Applications
Compressed air monitoring - Hygrometers measure dewpoint at the outlet of desiccant and refrigerated compressed air dryers
Natural gas processing - In the production and pipeline transmission of natural gas hygrometers are used to measure Pounds of Water per Million Standard Cubic Feet of Gas (#MMSCF)
Hydrogen generators - Hygrometers are used to monitor the dewpoint of hydrogen gas used to cool electric generating turbine generators during electricity production
Semiconductor manufacturing - Dewpoint measurement of inert gases to the parts per billion level (ppb) used in wafer and components manufacturing
Sulfur hexafluoride monitoring - Hygrometers monitor the dewpoint of sulfur hexafluoride gas (SF6) used in circuit breakers and transformers
Cermax Portable Hygrometer 
Kahn’s Cermax portable hygrometer monitors or spot checks the dewpoint of any flammable or non-flammable process gas such as compressed air, nitrogen, natural gas, or hydrogen. Features include:
Easy operation – simply connect the sample gas to the inlet port compression fitting, turn on the unit’s power and in seconds Cermax is ready to display the dewpoint
Fast response – responds quickly to changes in moisture level
Data Logging – Record and trend dewpoint data simply with straightforward controls
Intrinsically safe model available (Cermax-IS)
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Specifications
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Measurement range
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Cermax and Cermax-IS: calibrated from –100 to 20°C dewpoints; readings –120 to 30°C DP
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Accuracy
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±1°C from –60 to 20°C dewpoint
±2°C from –100 to -60°C dewpoint
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Resolution
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0.1°C dewpoint, 3 significant figures for other units
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Operating pressure
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Vacuum to 400 bar (6000 psig) maximum
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Operating temperature
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Cermax and Cermax-IS: -20 to 50°C
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Flow
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0.5 to 10 normal liters/min (recommended rate)
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Cermet II Hygrometer 
Kahn’s Cermet II hygrometer (dewpoint measurement instrument) measures from -100° to 20°C dewpoint. The Cermet II includes a digital display with integral signaling conditioning board, ceramic dewpoint sensor, and an interconnecting cable. Cermet II features include:
Digital display
High accuracy and repeatability
PPMV pressure compensated readout
Dual alarm relays & scalable 4-20 mA output
NIST traceability
NEMA 4 sensor housing
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Specifications
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Measurement range
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-100° to 20°C
-148° to 68°F
0.001 to 9999 ppmv (pressure compensated)
0-1000 #MMSCF of natural gas (pressure compensated)
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Accuracy
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±1°C from –59°C to 20°C
±2°C from –100° to –60°C
Resolution 0.1°C from –79° to 20°C
1.0°C from –100° to –80°C
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Operating conditions
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Pressure: Vacuum to 5000 psig
Temperature: Sensor operating –40° to 60°C
Sensor compensated: -20° to 40°C
Display operating 0° to 50°C
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Flow
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Recommended rate: 1-5 L/min (2-10 scfh)
Velocity: 20 meters/second maximum
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Chilled Mirror Optical Hygrometers
Chilled Mirror Hygrometer Applications
·Gas Turbine Inlet Air Monitoring
Hygrometer measures moisture content drawn into gas turbine
·Utility Switchgear Performance Monitoring<
Hygrometers are used to monitor moisture content of SF6 insulating gas in high voltage switchgears.
·Electronic Component Manufacturing
Hygrometer monitors dewpoint levels in moisture sensitive production processes including semiconductors and integrated circuits.
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Kahn has over 20 years experience with chilled mirror optical hygrometer technology. Today, Kahn manufactures accurate and drift free chilled mirror hygrometers capable of measuring moisture in the parts per billion range.
How it Works
1. The mirror is chilled by a Peltier thermoelectric heat pump.
2. A light is focused on the mirror.
3. The photodetector measures the amount of light being reflected or scattered off the mirror.
4. A platinum resistance thermometer (PRT) measures the temperature of the mirror, which is dewpoint (frostpoint).
OPTIDEW VISION OPTICAL HYGROMETER
The Optidew Vision is a high performance, optical dewpoint hygrometer consisting of remote
temperature and dewpoint sensors, interconnecting cables and a separate display unit mounted in a
contemporary bench-top housing with ergonomic carrying handle. It measures dewpoint, temperature,
and relative humidity and provides visual indication of these measurements on a high definition
alphanumeric display. The instrument utilizes Kahn’s proven optical dewpoint measurement
technology well know for its high accuracy, repeatability, stability and ease of use in
laboratory and calibration applications.
Key features of the Optidew Vision include:
Single stage, two stage or high temperature sensor for a full range of dewpoint measurements
Wide dewpoint measurement range of -76° to +194°F and 0.5 to 100% relative humidity
Sealed water tight sensor, for use in condensing conditions, prevents corrosion or contamination of optical components
Multiple measurement units, including °F or °C dp, %RH, °F or °C temperature, g/m3; g/kg
Dynamic Contamination Correction (DCC) which provides better accuracy by differentiating between mirror contamination and excess condensation at high dewpoints
Flexible outputs that can be scaled and programmed for various measurement units
Optional panel mounting kit for permanent control room installation
OptiDew Specification Sheet (PDF)
OPTI-CAL HUMIDITY CALIBRATOR
Opti-Cal is a portable, fully self-contained humidity/temperature calibrator designed for
calibrating relative humidity (RH) sensors. The system consists of a humidity/temperature-controlled
chamber that can house up to six or more RH sensors, depending on their physical dimensions, and
includes a built-in Optidew reference hygrometer for precise, continuous monitoring.
Opti-Cal works by time proportioning the flows of dry and saturated air according to the pre-selected
relative humidity value to enable the calibration humidity to be varied between 10% and 90%
RH over a 10? to 50?C (50? to 122?F) chamber temperature range. The chamber temperature is controlled
by a four-zone thermo-electric heat pump arrangement for maximum and minimum temperature gradient.
The saturator assembly can be filled easily with distilled water at the front of the unit and the
easily accessible desiccator can be re-charged by heating when required. The only external service
required is a single-phase, 115 VAC power source.
Key features of the Opti-Cal Humidity Calibrator include:
Simple and easy to use
Fully self-contained and portable
10-90% relative humidity range over a 10° to 50°C chamber temperature range
Uniform chamber temperature control
Re-chargeable desiccator
Local or remote setpoint control
Bundled Windows application software to monitor, chart and log calibration reference data
Built-in Optidew reference hygrometer for NIST traceable calibration
Series 4000
 Kahn’s Series 4000 chilled mirror hygrometers are the most accurate and versatile optical hygrometers available.
Features
Dewpoint measurement from –100 to 85°C
Accuracy: ±0.1°C
Durability: all electronic components are shielded from water
Resolution: ±0.1°C
3 stage Peltier cooling
Automatic Contamination compensation
Current, voltage, and RS232 outputs
Dual optics detection system
Stainless steel gas-wetted parts
Precision platinum resistance thermometer
Microscope to monitor condensation on mirror
Built-in data hold function
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Model S4000 Integrate
Lightweight with measurement to –60°C
Dual display: °F or °C dewpoint and PPM or %RH
Model S4000 Remote
Remote sensor in a compact housing
Climate version: dewpoint to +85°C
Model S4000RS
Temperature controlled sensor body for dewpoint measurements to –85°C (230 ppb)
Model S4000TRS
Temperature controlled sensor body for dewpoint measurements to –100°C (13 ppb)
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