Analytical Industries Ambient Monitor

The Analytical Industries’ experience in designing precise and reliable oxygen monitors equipped with proprietary oxygen sensors proven in thousands of personal oxygen alarms and diving equipment offer the highest level of protection to the staff that depends on such room oxygen monitors. Our oxygen analyzer range also includes oxygen deficiency monitors with remote sensors.

Analytical Industries Ambient Monitor Features

  • Low maintenance with typically 32 months oxygen sensor life
  • Audible and visual oxygen deficiency alarm available
  • Up to four measurement ranges
  • Accuracy of <2% of span
  • Mains power with battery back-up (GPR-35)
  • Remote oxygen sensor & pump options (GPR-35)
  • Analog output for connection to DCS
  • 12-28 V DC operation (GPR-2500 versions)


  • Cylinder storage areas
  • Rooms with gas lines
  • Rooms with purged processes or vessels
  • Large chambers that are purged with inert or other gases
  • Confined spaces


The GPR-35 is specifically designed for ambient monitoring and has an accuracy of better than 2% of reading under constant conditions. This model offers barometric pressure and temperature compensation, is mains powered with a battery back-up that will last up to 8 hours in alarm mode. It is supplied with dual red/ green alarm indicators, low battery and failure LEDs and a 0-1V output. Other features include two adjustable alarms for oxygen concentration and these are pre-set to OHSA levels of 20.0% (caution) and 19.5% (danger).


For measuring ambient air in general purpose or hazardous area, the GPR-2500 SN is ideal, it is 18- 24V loop powered with ranges of 0-1%, 0-5%, 0-10% & 0-25% O2. The unit is a basic 24V loop powered transmitter with the sensor located at the bottom of the NEMA box and open to the atmosphere. When used in a hazardous area an external barrier (MTL7706+ or equivalent) is required. The XLT sensor is available with this model.


For measuring ambient air in a hazardous area, the GPR2800 is ideal, with a single range of 0-25% O2. The unit is a basic 24V loop powered transmitter with the sensor located at the bottom of the NEMA box and open to the atmosphere. The XLT sensor is available with this model.AII GPR-2800 AIS S

The AIS model adds alarms and the ability to be mains powered as well as the option of MODBUS (24V DC only) providing greater flexibility.

Analytical Industries Ambient Monitor Specifications

GPR-35 GPR-2500-S GPR-2800-IS/AIS-S
Measurement range 0-25% 0-25% 0-25%
Accuracy < 2% of range at constant conditions
Response time T90 < 10 seconds
Sensitivity (LDL) 0.1% O2
Linearity < 1% of scale
Sensor model GPR-11-32-RTS GPR-11-32-4
XLT-11-24-4 for gases containing >0.5% CO2
Sensor life at 25ºC (77°F) and 1 atm 32 months in air GPR-11-32-4 32 months in air 5°C and 1 atm
XLT-11-24-4 24 months in air 5°C and 1 atm
Calibration interval 30 days
Inlet pressure Atmospheric sampling
Gas connections None
Display 3½ digit LCD; resolution 0.1 LCD 7 x 3.5cm (2.75 x 1.375″); resolution 0.1%
Enclosure Painted aluminum, suitable for indoor use only Fiberglass NEMA 4X Fiberglass NEMA 4X, plus painted aluminum Exd enclosure
Dimensions 10.1 x 22.8 x 7.6cm (4x9x3″) 17.1 x 21.3 x 10.8cm (6.75 x 8.375 x 4.25″) 25.3 x 40cm (10 x 15.7″)
Weight 3.6kg (8lbs) 6.5kg (14.6 lbs)
Compensation Barometric pressure and temperature (GPR-35 and GPR-2800 AIS S)
Temperature (GPR-2500 and GPR-2800 IS S)
Signal output 0-1V 4-20 mA (or 1-5V on GPR-2800 AIS)
Alarms Two adjustable SPDT Form C non-latching relay contacts None Two user-configurable alarms magnetic coil relays rated 3A at 100 V AC (AIS only)
Operating temperature 0°C to 45°C (32°F to 113°F) GPR sensor: 5°C to 45°C (41°F to 113°F)
XLT sensor: -10° to 45°C (14°F to 113°F)
Humidity Non-condensing up to 95% RH
Power 100-240 V AC with battery back-up (battery life up to 30 days or 8 hours in alarm mode) 18-28 V DC 18-24 V DC (IS model)
18-24 V DC or 110 to 220 V AC (ATEX AIS only)
Area classification General purpose CSA/NRTL approved General purpose or with external safety barrier MTL-7706 or equivalent
Ex ia IIB T4 Gb
Tamb -20°C to +50°C
Ex d [ib] ib IIB Gb T4
Tamb -20°C to +45°C

Download Datasheet: Analytical Industries Fixed Ambient Oxygen Deficiency Monitors with Alarms

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