MUNI MP420 Multi Gas Compliance Detector

The MUNI Diffusion Gas Detector MP420 is a basic 4 gas detector for worker safety in hazardous locations, with oxygen, combustible, carbon monoxide and hydrogen sulfide sensors. Hydrogen Cyanide and Sulfur Dioxide sensors are also available.

For pricing, please call 1-800-952-3293 or email


The MUNI Diffusion Gas Detector MP420 is a compact and lightweight 4 gas detector for worker safety at hazardous locations. It features 4 sensors including Oxygen, Hydrogen Sulfide, Carbon Monoxide and combustible gases. Other sensors available include a lead free Oxygen sensors, a low powered infrared methane sensor, sulfur dioxide and hydrogen cyanide. The detector is packaged in a robust housing with no moving parts. Its battery power offers 2 work shifts of run time for a standard 4 gas meter and up to one week when using a low power infrared sensors. The simple 2 button operation results in ultimate ease of use and significantly reduced time spent training the user.


  • Diffusion sampling
  • Compact, robust, lightweight and wearable
  • Auto backlit LCD with large numeric digits
  • Easy to navigate menu with two buttons
  • Battery operation 24 hours with pellistor LEL sensors or 1 week with low power infrared LEL sensor
  • Tri color status indicators on regular self diagnosis of sensor, battery and circuit
  • Wide angle LED alarms
  • 1,000 events log
  • Combination of charge adapter/micro USB PC interface cable
  • IP68 weather ingress rating
  • Replaceable sensors and batteries
  • Optional BLE wireless connectivity
  • Optional MuniDock for convenient bump and calibration

Instrument Specifications

Detector Electrochemical for Oxygen, Carbon Monoxide, Hydrogen Sulfide, Sulfur Dioxide
Pellistor for Combustible
Lead-Free Oxygen
Battery Rechargeable Lithium-ion
Operating Periods Up to 24 hours with Pellistor and 1 week with NDIR Sensors
Graphic Display Segment LCD, 1.75 x 1.25″
LED backlight for enhanced display
Keypad Two button operation
Direct Readout Real time reading of gas concentrations
Battery status
Visual compliance indicator
STEL, TWA, peak and minimum values
Alarm Audible: 95 dB @ 30 cm
Visual: Tri color LEDs
EMI/RFI EMC directive: 2014/30/EC
IP Rating IP68
Data Logging 1,000 events including alarm, function tests and calibrations
Communication & Charging Charging with AC adapter or cable PC
PC Comm for data download, monitor setup & firmware upgrades via cable
Optional BLE or MuniDock
Temperature -4° to 122°F
Humidity 0-95% rH, non-condensing
Size 4.33″ x 2.36″ x 1.10″
Weight 8 ounces
Approvals Ex da ia IIC T4 Ga
Class I, Div 1, Groups A, B, C, D

Sensor Specifications

Combustible Gas
1-100% LEL
Carbon Monoxide
0-1,000 ppm
1 ppm
Hydrogen Sulfide
0.1-100 ppm
0.1 ppm
Hydrogen Cyanide
0-50.0 ppm
1 ppm
Sulfur Dioxide
0.1-20 ppm
0.1 ppm

Ordering Information

Each MUNI Multi Gas Detection instrument includes monitor and sensors as specified, AC charging adapter, calibration cap, USB Communication cable, calibration certificate and quick reference guide. For pricing, please call AFC International at 1-800-952-3293, 219-987-6825 or fax 219-987-6826 or email

Catalog No.
MUNI 4 Gas Detector, LEL, O2, CO, & H2S Sensors, 2 year warranty MP42-20121-100
MUNI 3 Gas Detector, NDIR LEL, O2, CO & H2S Sensors, 3 year warranty MP42-20122-200

MUNI Diffusion Gas Detector literature 

Product Literature

POLI Diffusion Gas Detector literature
Tech Note 3 – Calibration Frequency
Tech Note 4 – Sensor Technical Data Summaries
Tech Note 5 – Gas Detectors for Firefighters and Hazmat Teams

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