AMETEK Western Research 933 UV Hydrogen Sulfide Analyzer for Natural Gas

The AMETEK Western Research 933 Hydrogen Sulfide Analyzer is an integrated, panel-mounted analyzer for low-level hydrogen sulfide (H2S) in natural gas. It combines AMETEK frontal elution chromatography sampling with a multi-wavelength ultraviolet optical bench and is designed for unattended operation over long periods.

Seven Star LLC supplies the 933 from Muscat with the manufacturer data sheet available before quotation.

Frontal elution sampling with UV photometry

The 933 separates H2S, and optionally carbonyl sulfide (COS) and methyl mercaptan (CH3SH), from interfering components in natural gas using proprietary frontal elution chromatography. Detection is by a non-dispersive, dual-beam hollow cathode UV photometer, which AMETEK states gives accuracy better than 0.25 ppm. H2S is measured directly, with no scrubbing.

Two self-regenerating columns are used. While one column conditions the sample, the other is regenerated automatically, so the analyzer recovers by itself after high-concentration H2S events and uses no consumables, reagents or disposables other than zero gas.

• Ranges from 0-3 to 0-100 ppm H2S
• Optional COS, CH3SH and CO2 measurement
• Fast response and fast recovery
• Fully integrated analyzer and sample system

Technical specifications

Applications and what to confirm before ordering

AMETEK lists natural gas sweetening, amine contactor overhead, custody transfer stations, pipelines, synthetic natural gas, blending stations, CO2 purity and biogas. Key markets are natural gas, refining, chemical and petrochemical, and industrial gas.

The data sheet states that the 933 meets various ATEX, IECEx, CSA, NEC and GOST hazardous-area requirements and refers readers to AMETEK for specific details, so state the required approval when requesting a quotation. Also confirm the H2S range, which optional components (COS, CH3SH, CO2) are needed, the sample pressure, and the supply voltage.

How the AMETEK Western Research 933 H2S analyzer works

Natural gas contains many components, and some of them disturb the optical measurement of hydrogen sulfide. The 933 first separates H2S from these components with frontal elution chromatography. The gas then enters a dual-beam ultraviolet photometer, which measures how much light the H2S absorbs. There are two columns. While one column works on the sample, the other is regenerated, and they alternate automatically. This lets the analyzer recover by itself after a high H2S event, and it needs no reagents or consumables apart from zero gas.

Where the 933 is used

• Natural gas sweetening plants and amine contactor outlets.
• Custody transfer stations and pipelines.
• Blending stations and synthetic natural gas.
• CO2 purification and similar process streams.
• Sites that need unattended H2S monitoring over long periods.

Selection checklist for the 933

• Range: standard 0 to 25 ppm, up to 100 ppm, or low range 0 to 3 ppm, up to 50 ppm.
• Accuracy, plus or minus 2 percent of full scale in the standard range.
• Optional measurement of COS, methyl mercaptan and CO2.
• Process pressure of 830 to 13,790 kPag.
• Outputs: up to four isolated 4-20 mA signals and five alarm relays.
• Communication by Modbus RTU RS485, or Modbus TCP over Ethernet.
• Power supply: 104 to 132 VAC or 207 to 264 VAC.
• Ambient temperature of 0 to 50 degrees C.
• Panel size of 780 x 1185 x 254 mm and a weight of about 100 kg.

Installation, commissioning and maintenance notes

Install the panel in a suitable shelter close to the sample tap, and keep the sample line short and clean. Set the sample flow to the typical 2.5 L/min and supply zero gas of the specified quality. Calibrate with a certified span gas at commissioning and compare the output with a laboratory check. Record the response time and the alarm settings, and plan routine checks of the sample system filters.

Requesting a quotation for the AMETEK Western Research 933

Send the gas composition, the H2S range, the pressure and the outputs needed. Seven Star LLC serves industrial customers in Oman and the GCC and replies with a quotation based on the information provided.

Direct measurement without scrubbing

H2S is measured directly, with no scrubbing of the gas, which avoids the errors that a scrubber can add.

Fast response

The 90 percent response is under 30 seconds for H2S, so process upsets can be seen quickly and acted on.

Records of calibration

Keep the span gas certificate and the calibration results with the analyzer file.

Sample conditioning for the analyzer

A clean, dry and steady sample gives the best result. Use a membrane filter near the tap, keep the sample line at a temperature above the dew point of the gas, and avoid dead legs that can store H2S and delay the reading.

Ordering information

The manufacturer data sheet is available before quotation, so the range, the outputs and the options can be checked against the plant needs.

Documents and quotation

To request a quotation for the 933 analyzer, send Seven Star LLC the full model or order code, quantity, and any nameplate data from an existing unit that is being replaced or matched. Our Muscat team checks the request against the manufacturer document, which can be downloaded from this page, and replies with a formal quotation. Prices, stock and lead times are confirmed per inquiry.

Related reading on this site: the gas analyzer systems category, and AMETEK 930 sulfur pit H2S analyzer.