AII GPR-7500 (A)IS Hydrogen Sulphide Analyzer

Overview

The AII GPR-7500 (A)IS is an online hydrogen sulphide analyzer from Analytical Industries Inc. (AII) that uses low-power electrochemical sensor technology to measure H₂S in natural gas and biogas. It covers full-scale ranges from 0–20 ppmV up to 0–2000 ppmV, is certified for use with flammable gas streams, and ships with a dedicated sample-handling system so it can be connected to the process with little additional engineering. Two versions are offered: the loop-powered GPR-7500 IS and the line-powered GPR-7500 AIS, which adds Modbus and alarm relays.

Seven Star LLC supplies the AII GPR-7500 to gas producers, utilities and biogas operators in Oman and the GCC, with engineering support in Muscat. Sour gas, which the AII GPR-7500 is designed to monitor, is a defining feature of many fields in the region, and a compact, certified H₂S analyzer is a practical way to verify sweetening performance, protect downstream equipment and confirm gas quality at custody points and fuel gas skids.

Measurement Principle of the AII GPR-7500

As general engineering background, an electrochemical H₂S sensor oxidises hydrogen sulphide at a working electrode and the resulting current, measured against a counter electrode, is proportional to H₂S concentration. Because these cells need oxygen and moisture to function and can saturate at high concentrations, the sample is normally diluted with air before it reaches the sensor, which also extends the usable range and protects the cell.

The AII GPR-7500 applies this approach with AII OSV-72 series sensors and a defined air-to-sample dilution ratio. The OSV-72-7H sensor covers 0–500, 0–1000 and 0–2000 ppmV using a 1:10 air-to-sample ratio, while the OSV-72-7HH covers 0–20, 0–50 and 0–100 ppmV at a 1:1 ratio; -LD versions of both are available. Dilution air can come from ambient air via an optional pump or from compressed air. The datasheet states accuracy better than 2 % of the selected range, 0.01 ppmV resolution, a lower detection limit of 0.1 ppmV and a T90 response under 60 seconds.

Engineering Design of the AII GPR-7500

The AII GPR-7500 is built on a backplate carrying an explosion-proof housing, the analyzer enclosure in painted aluminium and fibreglass, flow indicators and the sample-handling components. An optional liquid drain removes entrained liquids from wet gas before the sample reaches the sensor, and the optional air pump supplies dilution air where no instrument air is available. Sample pressure should be 5–30 psi (0.3–2 bar), and the instrument operates from −10 to +45 °C with 15–90 %rh non-condensing humidity.

The GPR-7500 IS is loop powered from 12–28 V DC at about 1 W and sends a 4–20 mA signal, while the GPR-7500 AIS is powered from 12–24 V DC, consumes up to 28 W and adds Modbus communication plus two user-configurable alarm relays. Hazardous-area certification includes ATEX and IECEx Ex db ia IIC T4 Gb without the air pump and Ex db ia IIB+H2 T4 Gb with it, and cMETus Class I, Division 1, Groups B, C and D T4, for ambient temperatures from −20 to +50 °C, referencing EN 60079-0:2018 and IEC 60079-1:2014.

Key Features

These features make the AII GPR-7500 a practical choice for continuous H₂S measurement.

• Ranges from 0–20 ppmV to 0–2000 ppmV cover both treated gas specifications and raw biogas levels.
• A dedicated sample-handling system is included, reducing site engineering and commissioning time.
• Air dilution at defined ratios protects the sensor and extends its measurement capability.
• An optional liquid drain handles entrained liquids in wet natural gas or biogas samples.
• An optional air pump allows operation where instrument air is not available.
• Loop-powered IS and line-powered AIS versions suit both simple and fully networked installations.
• Modbus communication and two configurable alarm relays are available on the AIS version.
• Hazardous-area approvals under ATEX, IECEx, UKEx and cMETus support installation close to the process.

Industrial Applications

AII lists natural gas quality and biogas before and after the H₂S scrubber as the main duties for the AII GPR-7500. In GCC upstream and midstream operations the analyzer suits outlet monitoring on amine and scavenger sweetening units, fuel gas supply to turbines and fired heaters, city-gate and gas network pressure-reduction stations, and checks that treated gas stays within contract H₂S limits. In wastewater treatment and landfill gas projects, it can confirm scrubber performance before biogas is burned in engines or boilers, protecting them from corrosion.

In Oman, sour gas production in the interior, gas processing plants and power stations that burn pipeline gas are natural users, as are municipal wastewater and biogas schemes around Muscat. Seven Star LLC supplies the AII GPR-7500 with replacement OSV-72 sensors and sample system spares, backed by engineering support in Muscat. For other sulphur measurement technologies on our site, compare the Applied Analytics OMA-300 H2S analyzer, the ProTech903 tape-based H2S and total sulfur analyzer and the ProTech 1000 Z2 tape-based H2S analyzer.

Technical Specifications

The AII GPR-7500 (A)IS specifications below are taken from the AII datasheet PST-DS-3300-1.1 (06/2024); performance is application dependent.

How to Order

Request a quotation for the AII GPR-7500 from Seven Star LLC by sending your gas composition, expected H₂S range, available utilities and area classification, and our instrumentation division will specify the sensor, dilution and sample options. Download the manufacturer datasheet from this page and contact our Muscat office for availability, lead time and engineering support in Oman and the GCC.