The MK440 Environmental Noise Monitor is a compact, light and easy-to-deploy noise monitoring instrument, perfect for measuring and monitoring environmental noise.

Built on the technology of the MK427 NoiseSensor, the MK440 can be integrated into an existing PLC data logging and monitoring system with relative ease, eliminating the need for a lengthy and complicated set up procedure. Unlike conventional sound level meters (like the Optimus+ Green), the MK:440 Environmental Noise Monitor converts the noise level (decibels), into an industry-standard 4-20mA output, which can be connected to a standard DCS/SCADA-based PLC system, allowing you to add noise measurement capability to an already-established system.

With no dials, controls or displays, the MK440 is incredibly easy to install and use. Once in place and connected to your system, place an acoustic calibrator on the microphone to calibrate the monitor and apply the noise level to current conversion to the control system to enable noise levels to be measured in decibels. You won’t have to spend time learning how to use a whole new piece of equipment - simply plug it in, and the MK:440 Environmental Noise Monitor will start working.

Approved for use in hazardous environments

The MK:440 Environmental Noise Monitor has been certified non-incendive for use in Class 1 Division 2 hazardous environments (United States and Canada), which include locations like mines, gas pumps and stations, processing plants, and food and beverage maufacturing locations.

Approved by FM Approvals, the MK:440 Environmental Noise Monitor can be used to monitor noise levels in potentially dangerous environments, without fear of flammable vapor, gas or liquids being ignited by the instrument. If you're already monitoring environmental/atmospheric conditions in a hazardous environment and need to start monitoring noise, the MK:440 is the solution you need.

  • Lightweight and compact
  • Weatherproof design
  • Easy to install and set up
  • Designed specifically for integration into existing systems
  • No user-intervention required to record noise levels
  • Approved for use in non-incendive Class 1 Division 2 areas
  • Airport and aircraft noise monitoring
  • Construction site noise monitoring
  • Wind farm noise monitoring
  • Entertainment venue noise monitoring
  • Hazardous environments with potentially explosive atmospheres (Class 1 Division 2 areas)
  • Any system that requires noise data to be captured

Output type

A weighting SPL in 4-20mA loop

Frequency weighting


Time weighting - selectable at factory

Fast, slow

Measurement range - selectable at factory

64-134 dB

54-124 dB

44-114 dB

34-104 dB

24-94 dB

Current loop out

lout = 0.1A/dB





External power

12 to 24V DC



Cable entry

½” NPT or M20 Gland

Cable length

10m max

Operating temperature

-10 to +50⁰C

IP rating


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