BW Gas Alert Extreme Series Single Gas Detectors

The bright, large LCD shows real-time gas concentrations and the instrument's status at all times. The full function self-test verifies sensor, circuitry and battery integrity and activates the audible/visual alarms each time you turn the instrument on. The detector clearly advises the gas hazard present-Low, High, TWA and STEL gas alarm. Recorded TWA, STEL and Peak exposures can be displayed on demand.

GasAlert Extreme provides extraordinary cost of ownership advantages. These include automated calibration, 3-year lithium battery (available in local stores) and simple, one button control. Each of these features lowers your training and maintenance costs. Operated by an advanced micro-controller and an electrochemical sensor, the GasAlert Extreme is equipped with high output audible / visual alarms.

The compact, rugged GasAlert Extreme is designed with the most advanced RFI protection available today. Its IP 66/67 rating means its waterproof to 3ft (fully submerged) and the GasAlert Extreme also features a shock resistance concussion-proof boot. Delivered ready for use, simply clip the instrument to your pocket, belt or hard hat for unequalled protection.

Supported Gases

  • H2S - hydrogen sulfide
  • NO - nitric oxide
  • CO - carbon monoxide
  • HCN - hydrogen cyanide
  • O2 - oxygen
  • Cl2 - chlorine
  • SO2 - sulfur dioxide
  • ClO2 - chlorine dioxide
  • PH3 - phosphine
  • O3 - ozone
  • NH3 - ammonia
  • ETO - ethylene oxide
  • NO2 - nitrogen dioxide

Key Features:

  • Waterproof IP 66/67 rating up to 3 ft fully submerged
  • Integral concussion-proof boot
  • Continuous LCD shows real-time gas concentration with backlight in low light (auto); in alarm (auto) and on demand
  • Small size (1.1 x 2.0 x 3.75 in. / 28 x 50 x 95 mm) and lightweight (2.9 oz. / 83 g)
  • Provides 85 dB tone and bright LED indication on alarm (typical)
  • 3-year battery life (9,000 hours)
  • Available with internal vibrating alarm
  • Equipped with plug-in, replaceable sensor
  • Simple auto-zero and calibration procedure
  • Peak value displayed on command (in ppm or %)
  • LOW, HIGH, TWA and STEL alarms with adjustable setpoints
  • TWA (time weighted average) values are recorded and
  • displayed to evaluate the cumulative exposure danger and to aid regulatory compliance
  • Classified intrinsically safe by UL to U.S. and Canadian standards; Cenelec certified; certified in Australia
  • Full function self-test of: sensor, battery, circuitry integrity and audible/visual alarms
  • Pocket/belt clip, test cap and hose, battery, and instructions in local languages included


GasAlert for: Measuring Range Alarm Setpoints (Factory defaults are shown. Alarm levels are field-adjustable.) Relative Humidity
Operating Temperature
  TWA Alarm STEL Alarm Low Alarm High Alarm  
Hydrogen Sulfide (H2S) 0-100 ppm 10 ppm 15 ppm 10 ppm 15 ppm 15-90 -40 to +50 oC
-40 to +122 oF
Sulfur Dioxide (SO2) 0-100 ppm 2 ppm 5 ppm 2 ppm 5 ppm 15-90
Hydrogen Cyanide (HCN) 0-30.0 ppm 4.7 ppm 10.0 ppm 4.7 ppm 10.0 ppm 15-95
Carbon Monoxide (CO) 0-999 ppm 35 ppm 200 ppm 35 ppm 200 ppm 15-90 -30 to +50 oC
-22 to +122 oF
Chlorine (CI2) 0-50.0 ppm 0.5 ppm 1.0 ppm 0.5 ppm 1.0 ppm 10-95 -20 to +50 oC
-4 to +122 oF
Nitrogen Dioxide (NO2) 0-99.9 ppm 2.0 ppm 5.0 ppm 2.0 ppm 5.0 ppm 15-90
Ammonia (NH3) 0-100 ppm 25 ppm 35 ppm 25 ppm 50 ppm 15-90
Phosphine (PH3) 0-5.0 ppm 0.3 ppm 1.0 ppm 0.3 ppm 1.0 ppm 15-90
Ethylene Oxide (ETO) 0-100 ppm 1 ppm 5 ppm 1 ppm 5 ppm 15-90
Chlorine Dioxide (ClO2) 0-1 ppm 0.1 ppm 0.3 ppm 0.1 ppm 0.3 ppm 15-95
Ozone (O3) 0-1 ppm 0.1 ppm 0.1 ppm 0.1 ppm 0.2 ppm 15-90
Nitric Oxide (NO) 0-250 ppm 25 ppm 25 ppm 25 ppm 25 ppm 15-90
Oxygen (O2) 0-30.0% N/A N/A 19.5 % 22.5% 0-99

Auto zero Yes
Calibration Automatic
Backlight Low light (auto); alarm condition (auto); on demand
Full function self-test Verifies integrity of sensor, circuitry and battery; audible/visual alarms
Sensor Plug-in, electrochemical cell (temperature compensated)
INDICATORS AND ALARMS Clearly advises alarm levels both visually and audibly
Visual alarm Flashing, wide-angled alarm lens with dual red LEDs, plus alarm LCD readout
Audible alarm High-output, pulsing 85 dB at 1 ft. / 0.3 m (typical)
Confidence beep Every 5 seconds (field-selectable)
Other Low battery; off warning; sensor fail
Optional internal vibrator Vibrates in sync with audible and visual alarms
CONTINUOUS LCD DISPLAY Alphanumeric gas readout and status display advises:
Gas ppm or % Continuously displays gas concentration present
TWA and STEL ppm or % Records and displays on demand
Peak ppm or % Records and displays peak (maximum) exposure to gas on demand
Setpoints Displayed on activation (auto) and on demand in ppm or %
Full function self-test Full function self-test on activation (auto)
GENERAL SPECIFICATIONS Impact-resistant ABS enclosure
Humidity 5% to 95% RH (non-condensing) (15% to 90% non-condensing for PH3 and NH3)
EMI/RFI Complies with EMC Directive 89/336/EEC
Battery type 3-volt lithium (camera battery available locally)
Battery life 3 years (9,000 hours)
Size 1.1 x 2.0 x 3.75 inches / 28 x 50 x 95 mm
Weight 2.9 oz. / 83 g
WARRANTY 2 years including sensor, except NH3 (one year)

This gas detector unit has the following replacement sensors available, depending upon individual configuration:

SR-X10-C1 Replacement oxygen (O2) sensor
PS-RH04S Replacement hydrogen sulfide (H2S) sensor
PS-RM04 Replacement carbon monoxide (CO) sensor
PS-RM04H Replacement carbon monoxide (CO) sensor, H2 resistant
PS-RS04 Replacement sulfur dioxide (SO2) sensor
PS-RC10 Replacement chlorine (Cl2) sensor
PS-RZ10 Replacement hydrogen cyanide (HCN) sensor
PS-RD04 Replacement nitrogen dioxide (NO2) sensor
SR-A04 Replacement ammonia (NH3) sensor
SR-V04 Replacement chlorine dioxide (ClO2) sensor
SR-E04 Replacement ethylene oxide (ETO) sensor
SR-A204 Replacement ammonia (NH3) sensor, extended range
SR-N04 Replacement nitric oxide (NO) sensor

GasAlert Extreme (GAXT) Expert Product Review:

The Good:

Small, compact, easy to use and available with a variety of toxic gas sensors to choose from. Real-time gas concentration readings are displayed on the LCD. It can be turned on and off at the beginning and end of your shift. Sensors and batteries can be replaced to extend unit life.

The Bad:

The unit's 3V battery, while having a long life span, is not easily field replaceable, requiring the unit to be opened completely in order to change the battery.

The Bottom Line:

With its range of user options and functionality, the GAXT is ideal for many applications where toxic gases are a concern. It has a good history of being reliable and virtually problem free.

Full Review:

A popular unit, the GasAlert Extreme is a good choice for anyone wanting continuous, reliable protection in a long-term single gas detector. It is a good fit in virtually any application where toxic gases are a concern, such as Oil & Gas, Utilities, Municipalities, Refineries, Steel Mills, Pulp, Paper and more.

Regular maintenance is required on this model in the form of frequent Calibrations and battery replacements. Bump Tests can also be performed on the unit depending on personal preference or when site safety regulations require it.

Available sensors include H2S, CO, SO2, PH3, Cl2, NH3, NO2, HCN, ETO, O3, NO and Oxygen, but as a single gas detector you can choose only one of those sensors available, not multiple sensors. The built-in concussion proof boot provides excellent protection against accidental bumps, scratches and damage; and it is water-proof, with an IP rating of 67 it can be submerged in water up to 1 m deep for 30 minutes.

The real-time gas concentration is displayed continuously on the LCD so you will always know the current levels, even when the unit is not in alarm. The unit has a built in Datalogging feature, enabling you to retrieve a detailed and accurate history of conditions and unit maintenance if needed.

Calibrating the unit is required every 90 days but is quick and easy to perform; the procedure can be done in the field and only takes about 2 minutes to perform, and all you will require is a cylinder of calibration gas and a regulator. It is also compatible with the BW MicroDock II calibration and bump test station for those who wish to use a more hands-free, automated, calibration and bump test procedure.


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