Gas Density Meter GD80, GD802G, GD802S

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Rapid Concentration Monitoring Through Density Measurement

The gas density meter consists of a GD80 detector and either a GD802G or GD802S* converter for continuous gas composition monitoring, with explosion-proof and non-explosion-proof configurations available.
*GD802S Ex-proof Gas Density Converter will be released soon.

Continuous gas density measurement determines the mixing ratio of known binary gas mixtures and detects composition changes in approximately 5 seconds.

A single meter requires only simple sampling, eliminating extensive pretreatment and helping improve operational efficiency while reducing operating costs.

The system can also be used for Hydrogen purity and Gas replacement concentration monitoring. Rather than measuring gas concentration directly, the system calculates gas concentration from the measured mixing ratio.

[ Available Conversion and Display Items ]

Converted values: Specific gravity, Molecular weight, Gas concentration
Application-specific values: Hydrogen purity (H₂ in Air) , Gas replacement concentration (H₂ in CO₂, Air in CO₂)

Proven and Trusted Measurement Technology
Proven across power generation, oil and gas, petrochemical, and steel industries, Yokogawa's gas density measurement technology has long supported reliable process monitoring.
In hydrogen cooling applications for turbine generators, a single gas density meter can perform measurements that typically require two thermal conductivity analyzers, helping simplify system configuration and reduce maintenance requirements.

Supporting Carbon-Neutral Applications
Yokogawa is now extending its gas density measurement technology to emerging carbon-neutral applications such as water electrolysis and methanation processes. Fast response and proven measurement performance help support safe plant monitoring and stable operation.

Seamless System Integration
Support for Ethernet (Modbus TCP/IP) and RS-485 (Modbus RTU) enables seamless integration with recorders, monitoring systems, and plant control system.

Key Advantages

Support Stable Plant Operation

The automatic multi-mode oscillator minimizes drift and supports stable operation over time.

Monitor Process Mixing and Cross Leakage

Detect changes in gas concentration with high sensitivity and accuracy.

Capture Changes in Seconds

A fast T90 response of approximately 5 seconds enables rapid detection of gas composition changes.

Simple, Intuitive Operation

Quickly configure settings and check status through an easy-to-use interface.

Application Examples

*: Learn more in the application notes below.

Hydrogen Purity and Replacement Gas Monitoring in One System

What once required two instruments can now be accomplished with one. By switching measurement modes, the Yokogawa gas density meter monitors both hydrogen purity and replacement gas concentration in a single system.

Optimize Methanation Processes

The Yokogawa gas density meter can also measure flammable gases such as H₂. Continuous gas density measurement supports gas composition monitoring and process control, helping improve the stability and efficiency of methanation processes.

Early Cross-Leak Detection in Water Electrolysis

Water electrolysis gases consist primarily of hydrogen and oxygen, allowing gas concentration to be determined from gas density. Early detection of cross-leakage helps improve equipment safety and process stability.

Supporting FCC Top Gas Quality Control (Ex-proof)

Continuous gas density measurement enables monitoring of FCC top gas quality. Rapid detection of gas composition changes helps maintain product quality while supporting safe and stable FCC operation.

Specifications

Common Specifications

Sample Gas Conditions		Sample Gas: All gases except highly corrosive gases. Temperature: -10 to 60°C (No condensation) Pressure: 50 to 600 kPa abs Flow Rate: 0.1 to 1 L/min
Principle		Multi-mode resonant oscillation technology

Selecting a Measurement Model Based on the Measurement Target

Depending on the parameters you wish to measure, you can choose from two combinations of measurement models.
You can select either a combination of measurement models for a density meter, hydrogen purity meter, displacement concentration meter, and hydrogen purity/displacement concentration meter,
or a combination of measurement models for a hydrogen purity meter, displacement concentration meter, and hydrogen purity/displacement concentration meter.
Please contact us if you intend to use the device as a calorimeter.

	Model
Item	Density Meter ^*1	Hydrogen Purity Meter	Replacement Meter	Hydrogen Purity / Replacement Meter	Calorimeter ^*2
Actual Density	Y	Y	Y	Y	Y
Corrected Density	Y	Y	Y	Y	Y
Specific Gravity	Y	－	－	－	－
Molecular Weight	Y	－	－	－	－
Concentration	Y	－	－	－	－
H₂Concentration in Air	－	Y	－	Y	－
H₂Concentration in CO₂	－	－	Y	Y	－
Air Concentration in CO₂	－	－	Y	Y	－
Calorific Value	－	－	－	－	Y

(Y: Available, －: Not available)
Note: Density is the primary measurement. All other displayed values are calculated from the measured density.
*1: To use the instrument as a density meter, select Measurement “-A” for the GD80.
*2: Contact Yokogawa for use as a calorimeter

Performance Specifications

The following performance specifications apply when the detector and converter are used in combination with the Yokogawa-specified pressure transmitter, EJX310A Absolute Pressure Transmitter.

Measurement Model	Density Meter					Hydrogen Purity Meter	Replacement Meter		Calorimeter
Item	Density kg/m³	Density lb/ft³ ^*6	Specific Gravity	Molecular Weight	Concentration vol%	H₂in Air vol%	H₂in CO₂ vol%	Air in CO₂ vol%	Calorific Value MJ/m³ ^*1	Calorific Value kBTU/ft³ ^*6
Range	0 to 6 (corrected) 0 to 60 (actual)	0 to 0.4 (corrected) 0 to 4 (actual)	0 to 5	0 to 140	0 to 100	85 to 100 ^*2	0 to 100		0 to 133	0 to 3.5
Minimum Range	0.1	0.01	0.1	4	Equivalent to 0.100 kg/m³ density	－	－		Equivalent to 0.100 kg/m³ density
90% Response Time ^*3	Approx. 5 s					Approx. 5 s^*7	Approx. 5 s ^*7		Approx. 5 s
Linearity	±1%FS	±1%FS	±1%FS	±1%FS	±1	±1	±1		±1%FS
Repeatability	±0.001 or ±0.5%FS^*4	±0.0001or ±0.5%FS^*4	±0.001 or ±0.5%FS ^*4	±0.02 or ±0.5%FS^*4	±0.5 or concentration equivalent to ±0.001 kg/m³ density ^*4	±0.5	±0.5		±0.5% FS or calorific value equivalent to 0.001 kg/m³ density^*4
Zero / Span Drift ^*5	±0.003/month	±0.002/month	±0.003/month	±0.07/month	Equivalent to ±0.003 kg/m³ density/month	±0.5/month	±0.5/month		Equivalent to ±0.003 kg/m³ density/month

*1: Contact Yokogawa when measuring calorific value.
*2: Configurable from 0 to 100 vol% (default: 85 to 100 vol%).
*3: Time required for the reading to reach 90% of its final value after the indicated value begins to change (at a gas flow rate of 0.6 L/min).
*4: Whichever is greater.
*5: Provided that the detector, converter, and pressure transmitter are not affected by ambient temperature.
*6: Unit conversion from kg/m³ to lb/ft³ and from MJ/m³ to kBTU/ft³ is supported by the GD802G.
*7: When switching from the zero point CO₂ to the span point H_2.