Process Moisture Analyzer
TDLAS-based trace moisture measurement for natural gas and process applications
- Range
- 0.1 ppm – 30 %vol H₂O
- Accuracy
- ±1 ppm or ±1% of reading
- Response
- <2s T90
- Output
- 4-20mA, Modbus, HART
Overview
The GS8500-H2O uses tunable diode laser absorption spectroscopy for real-time moisture measurement from sub-ppm to percent levels — suited for natural gas dehydration monitoring, process gas drying verification, and combustion optimization.
- Tunable diode laser optical measurement
- Auto-validation with internal reference cell
- Heated optical path prevents condensation
- Configurable dual-range (trace + percent)
- ATEX Zone 1 certified field enclosure
- Remote diagnostics via Modbus TCP / OPC-UA
- TDLAS H₂O capability is shared with the brochure ZS8500 bench-top platform and ZS8200 OEM laser module — same physics, different form factors
Full Technical Specifications
Key Performance
| Metric | Value | Status |
|---|---|---|
| Range | 0.1 ppm – 30 %vol H2O | confirmed |
| Accuracy | ±1 ppm or ±1% of reading | confirmed |
| Response | <2s T90 | confirmed |
| Output | 4-20mA, Modbus, HART | confirmed |
Specifications
| Specification | Value |
|---|---|
| Range | 0.1 ppm – 30 %vol H₂O |
| Accuracy | ±1 ppm or ±1% of reading |
| Response | <2s T90 |
| Output | 4-20mA, Modbus, HART |
Deployment Environments
Common process environments where this model is evaluated.
Certification Scope
Standards are listed with scope and status so engineering review can verify the applicable enclosure, area, and safety case.
| Standard | Scope | Variant | Status | Document |
|---|---|---|---|---|
| CE | Approval listed in v1 certification badges | Project variant | approved | On request |
| ATEX | Approval listed in v1 certification badges; zone and gas-group scope not specified in v1 source data | Project variant | approved | On request |
Request Documentation
Request technical datasheets, user manuals, certificates, and application notes for this model.
Evidence Notes
TDLAS moisture architecture for process and purity gas duty
The v1 application set places this analyzer in natural-gas dehydration, process drying, flue-gas moisture, and UHP gas monitoring. The architecture depends on TDLAS H2O absorption, heated optical-path control, and matrix review where CO2, CH4, or saturated water vapor can affect the selected line.
Technical & Engineering Details
Secondary engineering detail — expand each topic for the full measurement, envelope, sample-system, calibration, and maintenance information.
01 Measurement Principle and Limits
How the measurement is bounded
TDLAS measures H2O absorption on a selected laser line for trace-to-percent moisture monitoring in process and purity gas applications.
Requires
- Heated optical path and sample path control to avoid condensation
- Matrix review for CO2-rich, CH4-rich, or hydrocarbon-rich process gas
- Auto-validation reference cell checks when used for long-running online duty
Interferents and Limits
- CO2 and CH4 spectral overlap can require matrix-specific line selection or compensation
- High-moisture conditions near saturation can exceed the selected absorption range
- Condensation in the optical path changes the measurement basis
- Sample below dew point without heated conditioning
- Moisture above the declared 30 %vol range
- Process pressure and ambient limits are not stated in v1 source data
02 Operating Envelope
Use these limits as selection inputs, then confirm sample condition, ambient exposure, and materials before quotation.
- Condensing sample without heated line or heated optical-path review
- Moisture above the declared 0.1 ppm – 30 %vol H2O range
- CO2-rich or CH4-rich gas without spectral-overlap review
03 Sample System Boundary
Sampling mode, conditioning components, and exclusions define where the analyzer responsibility ends and the sample system begins.
- heated optical path
- internal reference cell
- extractive sample line
- GS-SCS-800 heated sampling system when required
- Unheated wet sample lines for flue gas or saturated process gas duty
04 Calibration & Validation site-specific
Calibration method, interval, and traceability are shown only when structured data is available.
Zero / Span Method
Auto-validation with internal reference cell is listed in v1 features; full zero/span sequence is not stated
Interval
Not stated in v1 source data
05 Maintenance & Spares site-specific
Tasks, consumables, and access items are shown only when structured maintenance data is available.
- Verify heated optical-path and sample-line operation before moisture-critical duty
- Run internal reference-cell validation checks according to the site QA schedule
- Review sample conditioning when switching between trace, percent, natural-gas, and flue-gas applications
- Sample-line filter or conditioning parts when configured with extractive sampling
Frequently Asked Questions
What does the GS8500-H2O measure, and how?
The GS8500-H2O uses TDLAS — tunable diode laser absorption spectroscopy — to measure H₂O absorption on a selected laser line for trace-to-percent moisture monitoring in process and purity gas applications. The published range is 0.1 ppm – 30 %vol H₂O with ±1 ppm or ±1% of reading accuracy and a <2s T90 response.
What sample conditioning does the GS8500-H2O require?
It needs a heated optical path and sample-path control to avoid condensation, and runs in an extractive configuration that includes an internal reference cell and an extractive sample line. The GS-SCS-800 heated sampling system is the compatible conditioning path when required. Unheated wet sample lines for flue gas or saturated process gas duty fall outside the sample-system boundary.
Which gases or conditions can interfere with the moisture reading?
CO2 and CH4 spectral overlap can require matrix-specific line selection or compensation, so a matrix review is recommended for CO2-rich, CH4-rich, or hydrocarbon-rich process gas. High-moisture conditions near saturation can exceed the selected absorption range, and condensation in the optical path changes the measurement basis.
What duty falls outside the GS8500-H2O operating envelope?
Outside the envelope: a condensing sample without a heated line or heated optical-path review; moisture above the declared 0.1 ppm – 30 %vol H₂O range; and CO2-rich or CH4-rich gas without a spectral-overlap review. Process pressure and ambient limits are not stated in the v1 source data and should be confirmed before quotation.
How is the GS8500-H2O calibrated and validated?
Auto-validation with an internal reference cell is listed in the feature set; the full zero/span sequence is not stated, and the calibration interval is not stated in the v1 source data. Validation cadence is therefore site-specific and should follow the site QA schedule.
What approvals does the GS8500-H2O carry?
CE and ATEX approvals are listed for this model. The ATEX zone and gas-group scope is not specified in the v1 source data, so the applicable enclosure and area classification should be confirmed against the installation during engineering review.
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