Available Available for application review and quotation
Moisture & Dew Point Measurement Series
FAS-W

FAS-W Online Moisture & Dew Point Analyzer

Automatic chilled-mirror analyzer for direct water-dew-point measurement and pressure-based gas-moisture calculation across selectable ranges.

Brand: Vympel Manufactured by: LLC Scientific Production Association "Vympel", Russia Supply & support: Blue Dragon Technology
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Product Overview

Purpose-built measurement, clearly presented.

The FAS-W is an automatic condensation hygrometer for online measurement of water dew point and gas moisture. Version A measures dew point, Version B reports moisture concentration, and Version C combines both functions. An integrated absolute-pressure sensor supports pressure-based conversion between dew point and moisture concentration.

The analyzer is suited to gas conditioning, chemical and petrochemical processing, energy, metallurgy, mechanical engineering, and reviewed high-purity gas applications. Blue Dragon Technology reviews the required range, version, sample pressure and composition, supplemental cooling duty, sample conditioning, hazardous-area installation, outputs, and alarm integration before configuration.

Distinctive Capabilities

  • First-principle chilled-mirror measurement without long-term sensor drift
  • Integrated absolute-pressure measurement for pressure-based moisture conversion
  • Analogue, digital, and alarm interfaces for online process integration
  • Supplemental-cooling option for lower dew-point applications
Performance & Technical Data

The measurement method and the values that matter.

How it measures

Measurement Principle

The analyzer cools a controlled mirror until water condensation is detected. The mirror temperature at the onset of condensation is the water dew point. An integrated absolute-pressure measurement allows the analyzer to calculate moisture concentration for versions that include that function.

Measurement ParametersWater dew point and/or calculated moisture concentration, depending on version
Measurement PrincipleAutomatic condensation hygrometer / chilled mirror
Available VersionsA: dew point; B: moisture concentration; C: dew point and moisture concentration
Dew Point Range I-30 to +65 °C
Dew Point Range II-80 to +20 °C with supplemental analyzer-body cooling
Dew Point Range III-65 to +30 °C

Complete Technical Data

Moisture Range I
0.1-200,000 ppmV
Moisture Range II
0.1-40,000 ppmV
Dew Point Accuracy
±1.5 °C from +65 to -30 °C; ±2.0 °C from -30 to -65 °C; ±3.0 °C from -65 to -80 °C
Moisture Accuracy
±10% at 0.1-100 ppmV; ±5% at 100-200,000 ppmV
Maximum Operating Pressure
Up to 10 MPa
Pressure Measurement
Integrated absolute gas-pressure sensor
Digital Communication
RS-485, Modbus RTU; 500 V isolation
Analog Output
Active 4-20 mA; maximum 400 Ω load; 500 V isolation
Alarm Outputs
2 dry-collector outputs
Explosion Protection / IP
1 Ex d IIC T5 X / IP67
Power Supply / Consumption
20-27 VDC / ≤15 W
Dimensions / Weight
≤185 × 120 × 135 mm / ≤4 kg
Industrial Use

Applications and industries.

Typical Applications

Water Dew Point MeasurementGas Moisture Concentration MeasurementGas Dehydration MonitoringProcess Gas Moisture MonitoringSpecialty Gas Quality ControlHydrogen Moisture MonitoringNatural Gas Quality MonitoringTrace Moisture Measurement in Gases

Industries Served

Biogas & Renewable GasCarbon Capture, Utilization & StorageChemical ProcessingFertilizers & ChemicalsHydrogen & SyngasIndustrial GasesIndustrial ManufacturingMetals, Mining & MaterialsNatural Gas & LNGOil & GasPetrochemicalsPipelines & MidstreamPower GenerationSemiconductor & Electronics
Engineering & Integration

Built for specification, installation, and long-term operation.

The FAS-W is an online analyzer rather than a stand-alone sensor. The selected version, measurement range, pressure basis, supplemental cooling duty, sample panel, utilities, outputs, and alarm behavior should be defined as one measurement system.

System TypeOnline chilled-mirror analyzer
Available Outputs4-20 mA, RS-485 Modbus RTU, and two alarms
Pressure InputIntegrated absolute-pressure sensor
Project FocusSample conditioning and cooling duty

System Configuration

  • StandardFAS-W analyzer in Version A, B, or C with the ordered measurement range and output configuration
  • OptionalSupplemental analyzer-body cooling for the lowest dew-point range
  • Project EngineeredSample-conditioning panel with isolation, filtration, pressure and flow control, fast loop, bypass, calibration connection, and safe vent or return

Sample Handling

  • StandardDeliver a representative, single-phase gas sample within the configured pressure, temperature, and flow requirements
  • Application DependentControl pressure and line temperature so water or hydrocarbon liquid does not form upstream of the measurement chamber
  • Application DependentUse clean tubing and appropriate filtration while preserving the moisture content and response time of the sample

Installation & Utilities

  • StandardProvide 20-27 VDC power, approved cable entries, grounding, and environmental protection appropriate to the hazardous-area classification
  • OptionalProvide supplemental cooling and its associated heat rejection or environmental controls when the selected lower range requires it
  • Project EngineeredAnalyzer panel, enclosure, shelter, heating, ventilation, drainage, sample return, and utility isolation

Integration & Communications

  • Project EngineeredDefine engineering units, output scaling, register map, alarm setpoints, latching behavior, historian tags, and control-system responsibility

Calibration & Quality Control

  • StandardChilled-mirror measurement directly registers condensation temperature; the supplied configuration and pressure measurement should be included in the verification record
  • Application DependentEstablish mirror inspection, pressure-sensor verification, and comparison against an approved reference method or hygrometer

Maintenance & Service

  • StandardInspect and clean the mirror and sample path in accordance with the manufacturer manual, and verify stable pressure and flow
  • Application DependentMaintain filters, regulators, cooling hardware, valves, and tubing according to sample cleanliness and site service conditions

Safety & Application Considerations

  • StandardConfirm process pressure, gas compatibility, hazardous-area approval, electrical isolation, sample venting, and safe access for mirror maintenance
  • Application DependentPrevent unplanned condensation, liquid carryover, corrosive contamination, and uncontrolled discharge of process gas
Application Review

Application Engineering Notes

Range selection

The three dew-point ranges are separate configuration choices rather than one continuous -80 to +65 °C range.

Project configuration

The approved datasheet identifies the ordered version, calibrated range, pressure basis, supplemental cooling requirement, moisture units, and the process conditions for the reported value.

Project Delivery

Project Integration & Support Scope

Blue Dragon reviews the measurement objective, interfaces, documentation, commissioning, and lifecycle requirements as part of project configuration. The scope below identifies the principal items to confirm before order placement.

Measurement Objective
Continuous online measurement of water dew point, gas moisture concentration, or both, according to the selected FAS-W version and range.
Signal Outputs
Active 4-20 mA, RS-485 Modbus RTU, and two dry-collector alarm outputs are available. Final scaling, units, register use, and alarm assignment are project specific.
Data Integration
Integrate the analyzer with the DCS, PLC, SCADA, or historian using the approved analogue and Modbus interfaces. Define moisture or dew-point units, pressure basis, data quality flags, alarm mapping, and ownership of calculated values.
Alarms & Diagnostics
Configure high moisture or dew-point alarms, analyzer fault handling, cooling-related alarms where applicable, communication failure behavior, and the required local or control-room indication.
Documentation
The project package may include the manufacturer operating manual, approved datasheet, calibration information, hazardous-area certification, wiring and Modbus information, sample-system drawings, and commissioning records as ordered.
Commissioning Support
Commissioning can include sample-system leak and flow checks, pressure verification, supplemental-cooling checks, mirror condition, output scaling, Modbus communication, alarm tests, and comparison with an approved reference.
Lifecycle Support
Lifecycle support covers mirror and sample-path inspection, filter and regulator maintenance, pressure-sensor checks, cooling-system review, verification, troubleshooting, spare parts, and technical support through Blue Dragon Technology.
Online Analyzer Configuration

Sample System & Online Analyzer Readiness

Reliable online measurement depends on the process interface as well as the analyzer. Confirm the following application data before final configuration and quotation.

Sample Type & Phase
Dry or moisture-bearing industrial gas in a stable single-gas phase. Provide the complete gas composition and identify possible water, hydrocarbon, glycol, methanol, particulate, aerosol, or corrosive carryover.
Measurement Range
Select one manufacturer range and Version A, B, or C. State the normal and worst-case water dew point or moisture concentration, required units, pressure basis, alarm points, and whether supplemental cooling is required.
Sample Conditions
Provide source pressure, measurement pressure, normal and maximum temperature, expected flow availability, ambient range, composition, contaminant loading, and the required sample-disposal destination.
Sample Handling
Define the extraction point, tubing material and length, pressure reduction, filtration, fast-loop or bypass arrangement, flow control, calibration connection, and measures that prevent upstream condensation or ambient moisture ingress.
Installation Area
Confirm indoor or outdoor location, hazardous-area classification, ambient temperature, sun and rain exposure, available shelter or panel space, maintenance access, and the safe-zone boundary for ancillary equipment.
Utilities
Provide 20-27 VDC power and any supplemental-cooling utilities required by the selected range. Confirm grounding, cable entries, isolation, drainage, and sample vent or return provisions.
Response Requirement
State the required process-response time, distance from the sample point, fast-loop availability, alarm delay, and acceptable stabilization time following start-up or a process change.
Integration Requirement
Define 4-20 mA scaling, Modbus RTU communications, alarm contacts, tag naming, engineering units, historian requirements, control-system ownership, and any local indication.
Commissioning Requirement
Confirm the required leak test, flow and pressure checks, mirror inspection, cooling test, output and alarm simulation, Modbus verification, reference comparison, training, and commissioning records.
Operational Visibility

Alarm & Diagnostic Matrix

The FAS-W provides chilled-mirror dew-point measurement, pressure-based moisture calculation where configured, one active 4–20 mA output, RS-485 Modbus RTU, and two dry-collector alarm outputs.

Project Setpoint means the limit is selected for the ordered application. Recommended severity is generic website guidance; the site alarm philosophy is final.

High water dew point or moisture

Process Severity: Critical
Trigger / Basis
Measured dew point or calculated moisture reaches the configured high Project Setpoint.
Instrument Response
The analyzer continues local measurement and operates an assigned dry-collector alarm output; 4–20 mA and Modbus report the configured value.
Operator Response
Confirm units and pressure basis, check the gas process and sample system, inspect for upstream condensation, and verify against the approved reference.
Reset & Ownership
The DCS or PLC owns process action. Alarm assignment, delay, latching, fail-safe behavior, and reset are project configured.

Low water dew point or moisture

Process Severity: Advisory
Trigger / Basis
Measured dew point or calculated moisture reaches a configured low Project Setpoint where low monitoring is required.
Instrument Response
The second dry-collector output can be assigned to the low condition; normal measurement interfaces remain available.
Operator Response
Confirm range, pressure basis, supplemental cooling, sample stability, mirror condition, and reference agreement.
Reset & Ownership
Normally DCS or PLC owned. Use and reset follow the approved alarm philosophy and ordered output assignment.

Condensation detection invalid or unstable

Analyzer Severity: Critical
Trigger / Basis
The chilled-mirror control system cannot identify a stable valid condensation event.
Instrument Response
The current dew-point or moisture result is invalid and analyzer diagnostic status applies.
Operator Response
Check sample flow and pressure, mirror cleanliness, contamination, cooling condition, line temperature, and stable gas composition.
Reset & Ownership
Analyzer owned. Resume only after a valid stable measurement and the required verification.

Absolute-pressure input invalid

Analyzer Severity: Critical
Trigger / Basis
The integrated pressure measurement required for pressure-based moisture conversion is invalid or unavailable.
Instrument Response
Dew-point measurement may remain available, but calculated moisture concentration for Versions B or C is not valid.
Operator Response
Check the pressure range, process connection, stable measurement pressure, configured units, and pressure-sensor status.
Reset & Ownership
Analyzer owned for the input; DCS or PLC owns bad-quality handling for the calculated value.

Supplemental cooling insufficient

Utility Severity: Warning
Trigger / Basis
The selected low-dew-point range cannot achieve the required mirror depression or analyzer-body cooling condition.
Instrument Response
The analyzer cannot reliably reach the lower measurement range and the result is unavailable or unstable.
Operator Response
Confirm the ordered range, ambient condition, cooling utility, heat rejection, connections, and required stabilization.
Reset & Ownership
Analyzer or project cooling-system owned. Reset only after cooling is stable and reference performance is verified.

Sample pressure, flow, or temperature abnormal

Sample System Severity: Warning
Trigger / Basis
A monitored sample condition leaves its project-approved operating band or upstream condensation is possible.
Instrument Response
The analyzer or project sample-system logic flags the condition; the current measurement is treated as suspect.
Operator Response
Check pressure reduction, filtration, fast loop, flow control, line temperature, leaks, vent or return, and gas-phase stability.
Reset & Ownership
Project sample-system PLC or DCS owned unless the delivered analyzer explicitly monitors the condition.

Mirror or sample path requires cleaning

Maintenance Severity: Advisory
Trigger / Basis
Inspection, drift, slow response, or failed comparison indicates mirror or sample-path contamination.
Instrument Response
Measurement quality degrades and stable condensation detection may not be possible.
Operator Response
Isolate the sample safely, inspect and clean the mirror and sample path according to the manufacturer procedure, then verify the analyzer.
Reset & Ownership
Operator maintenance owned. Return to service follows an accepted comparison or verification.

4–20 mA signal fault

Integration Severity: Warning
Trigger / Basis
The receiving system detects a missing, invalid, or non-updating active 4–20 mA signal.
Instrument Response
Local and Modbus measurement may remain available while the analogue plant signal is unavailable.
Operator Response
Check scaling, units, pressure basis, loop load, isolation, polarity, wiring, and DCS or PLC input configuration.
Reset & Ownership
The receiving system owns loop-fault detection and reset; the analyzer owns output generation.

Modbus communication loss

Integration Severity: Warning
Trigger / Basis
RS-485 Modbus RTU data stops updating or the analyzer does not answer the master.
Instrument Response
Local and analogue measurement can remain available while digital data is stale or absent.
Operator Response
Check address, baud rate, polarity, termination, shielding, register use, cable, and master configuration.
Reset & Ownership
The receiving system owns communication-loss alarming and stale-data handling.

Power loss

Utility Severity: Critical
Trigger / Basis
The 20–27 VDC analyzer supply is lost.
Instrument Response
Local measurement, calculation, alarm outputs, 4–20 mA, and Modbus become unavailable.
Operator Response
Verify safe isolation, supply voltage, protective devices, grounding, cable entries, and analyzer condition before restart.
Reset & Ownership
The DCS or PLC owns loss-of-signal action; restart follows the approved commissioning and alarm-test procedure.
Technical Resources

Product Documents

Product Sheet first, followed by the Brochure, Manual, and any additional technical documents.

Application Engineering

Discuss your measurement application.

Share the sample, measurement range, operating conditions, project location, and timeline. Blue Dragon Technology will review the application and recommend the appropriate configuration.

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