Brand: General Monitors

General Monitors 51457-1 H2S Gas Sensor

Name: General Monitors 51457-1 H2S Gas Sensor – Datasheet & Quote
Brand: General Monitors

Description

Overview

The General Monitors 51457-1 H2S sensor is a toxic gas sensor for hydrogen sulfide detection from the General Monitors range of gas detection products, now part of MSA Safety. The official MSA datasheet for General Monitors H2S gas sensors identifies part number 51457-1 as an H2S sensor with a measuring range of 0-100 ppm, and the original listing describes the item as a TGD (toxic gas detection) sensor, range 0-100 ppm, part number 51457-1, supplied as part of a fire and gas detection system.

The 51457-1 H2S sensor is used to protect personnel and plant in environments where hydrogen sulfide can be present, such as oil and gas production, refining and wastewater treatment, by continuously measuring the gas concentration and driving alarms when the level exceeds the set point.

Engineering & Design

The 51457-1 is a metal oxide semiconductor (MOS) H2S sensor element designed for use with General Monitors gas detection transmitters, where it converts the gas concentration into an electrical signal for the transmitter electronics. In the General Monitors H2S sensor range, the 51457 series covers the 0-100 ppm, 0-50 ppm and 0-20 ppm measuring ranges (51457-1, 51457-5 and 51457-9 respectively), with the -1L, -5L and -9L variants supplied in a stainless steel body with lugs.

The sensor is installed in the gas detection transmitter head in the field, where it is exposed to the atmosphere being monitored. Accessories such as increased safety housings (for example polyester Ex e housings for ATEX applications) are available from the same product range to suit the hazardous area classification of the installation.

Key Features

General Monitors (MSA) 51457-1 H2S sensor for toxic gas detection
Measuring range 0-100 ppm (per official MSA datasheet and original listing)
Solid-state metal oxide semiconductor (MOS) detection of hydrogen sulfide
Sensor element for General Monitors gas detection transmitters
Part of a fire and gas detection system per the original listing
Replacement part for existing General Monitors installations

Applications

The 51457-1 H2S sensor provides H2S monitoring in oil and gas production facilities
Toxic gas detection in refineries and petrochemical plants
Personnel protection in sour gas and wastewater applications
Replacement sensor for General Monitors H2S detectors

Specifications

Manufacturer	General Monitors (MSA Safety)
Part number	51457-1
Type	H2S toxic gas sensor, metal oxide semiconductor (MOS), solid state
Measuring range	0-100 ppm
Application	Fire and gas detection systems (per original listing)
Related parts	51457-5 (0-50 ppm), 51457-9 (0-20 ppm); -1L, -5L and -9L versions with lugs
Body material	Stainless steel
Certifications	ATEX, CSA, IECEx, GOST-R
Electrical classification	Class I, Div. 1, Groups B, C and D; Ex d IIC
Response time	T50 < 14 s with wire screen flame arrestor; T50 < 30 s with sintered stainless steel flame arrestor (full scale gas, ANSI/ISA-92.0.01)
Ambient temperature range	ATEX/IECEx: -40 to +120 °C; CSA: -40 to +75 °C; FM: -40 to +60 °C (varies by approval)
Sensor life	3 to 5 years
S5000 sensor option code	M14 (passive MOS, 51457-1, stainless steel, 0-100 ppm H2S, ATEX)
Sensor housings	P/N 10252-1 explosion-proof (CSA, FM); P/N B14-020-1 polyester increased safety (ATEX)

Compatibility & Integration

The 51457-1 H2S sensor is the replacement sensing element for General Monitors H2S detection transmitters, and it is installed in the detector head where the atmosphere is sampled. When replacing a sensor, follow the transmitter calibration procedure so the system remains accurate, and confirm the measuring range of the installed transmitter matches the sensor range.

Before ordering, confirm the transmitter model and the required measuring range of your installation. Our team can verify the part number and compatibility against your system before dispatch.

Ordering Information

To order the General Monitors 51457-1 H2S sensor from Seven Star LLC, quote the part number and your detector details. We confirm availability and delivery to your site in Oman or anywhere in the GCC, and we verify the part against your gas detection system before dispatch.

How the MOS Sensor Works

Calibration and Accessories

Why Seven Star LLC

Seven Star LLC supplies gas detection sensors and safety instrumentation to industrial customers across Oman and the wider GCC region. Every General Monitors 51457-1 sensor we supply is checked against the part number before dispatch, and our team confirms the sensor matches your detector before you order.

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About brand

General Monitors makes fixed gas and flame detection systems for hazardous industrial sites. Four aerospace engineers founded the company in 1961 in El Segundo, California, to build hydrogen gas monitors for the US space program. It later moved to Costa Mesa and, in 1991, to Lake Forest, California. MSA Safety acquired General Monitors in October 2010, and its detectors are now sold as part of the MSA fixed gas and flame detection range.

Seven Star LLC is an independent supplier listing General Monitors gas detectors, flame detectors, ultrasonic leak detectors and replacement sensors for buyers in Oman and the GCC. Detectors and sensors are matched from the full model code on the label.

General Monitors company profile

Origin	Founded in 1961 in El Segundo, California, by four aerospace engineers making hydrogen detection equipment for the US space program
Location	Lake Forest, California, USA (since 1991)
Ownership	Part of MSA Safety since 14 October 2010
Product families	Catalytic and infrared point gas detectors, open-path infrared detectors, toxic gas sensors, multi-spectrum infrared and UV/IR flame detectors, ultrasonic gas leak detectors
Typical duty	Combustible gas, H2S and fire detection on wellheads, gas plants, refineries, offshore platforms and terminals

Milestones

1961: Four aerospace engineers found the company in El Segundo, California, making hydrogen detectors for the US space program.
1991: The company moves to Lake Forest, California.
2010: General Monitors becomes part of MSA Safety on 14 October.

General Monitors detectors and sensors

Model	Type	Typical use
S4000CH	Catalytic bead combustible gas detector	Point detection of flammable gases and vapours, including hydrogen
IR400	Point infrared hydrocarbon gas detector	Methane and hydrocarbon detection without catalyst poisoning, and in inert atmospheres
IR5500	Open-path infrared gas detector	Perimeter and line-of-sight monitoring across process areas and fence lines
TG5000, 51457-1 H2S sensor	General-purpose gas monitor; H2S replacement sensor (0-100 ppm)	TG5000 for combustible, toxic or oxygen monitoring in wastewater, utility and light industrial sites; 51457-1 for H2S detectors
FL4000H, FL5000	Multi-spectrum infrared (MSIR) flame detectors	Hydrocarbon fire detection with resistance to false alarms from sunlight and hot work
FL500	UV/IR flame detector	Hydrocarbon fire detection in compressor houses, pump rooms and loading areas
Observer-i	Ultrasonic gas leak detector	Detects the sound of pressurised gas leaks, including where wind disperses the gas before it reaches a point detector

Where General Monitors detectors are used

Gas and flame detectors form the field layer of a fire and gas system. In Oman and the GCC they are installed on wellpads and gathering stations, gas processing and sulphur recovery units, refineries, LNG plants, tank farms, loading terminals, offshore platforms and power stations. A typical layout combines point detectors near leak sources, open-path detectors across process areas, ultrasonic detectors on high-pressure gas equipment and flame detectors covering fire zones.

Ordering General Monitors equipment: what we need

Send the full model code from the detector label, which defines gas type, range, output, housing material, thread and approvals, plus the serial number. For replacement sensors give the detector model and the gas and range of the installed sensor. For a new detector add the gas or fire hazard, area classification, output required (4-20 mA, HART, Modbus or relays), mounting and the certification needed on site, such as ATEX or IECEx.

Facts checked against MSA Safety and General Monitors company information, October 2026.

Browse General Monitors products by category: Fire & Gas Detectors.

FAQ

Questions about the General Monitors 51457-1 H2S Gas Sensor

Answers from our engineering team on installation, compatibility and integration.

01What is the General Monitors 51457-1?

The 51457-1 H2S sensor is a General Monitors (MSA) toxic gas sensor with a measuring range of 0-100 ppm, per the official MSA datasheet and the original listing.

02What is the measuring range of the 51457-1?

The measuring range is 0-100 ppm of hydrogen sulfide; the related 51457-5 and 51457-9 cover 0-50 ppm and 0-20 ppm respectively.

03What type of sensor is the 51457-1?

It is a metal oxide semiconductor (MOS) H2S sensor element used with General Monitors gas detection transmitters, identified as a TGD sensor in the original listing.

04Can the 51457-1 be used in hazardous areas?

The sensor is used with the General Monitors detector range, for which increased safety housings are available (e.g. polyester Ex e housings for ATEX), matching the hazardous area classification of the installation.

05How do I order the 51457-1 sensor?

Quote the part number and your detector details to Seven Star LLC, and we confirm availability, compatibility and delivery to your site in Oman or anywhere in the GCC.