MSA’s Revolutionary TruCal Gas Sensor Technology

Don't ignore the hidden costs of gas detection. Gas detection is often viewed as a necessary capital expense. However, the long term operational costs such as replacement sensors, service engineers and calibration gas shouldn’t be overlooked.

MSA's breakthrough TruCal is a patented extended calibration technology that corrects sensor drift and extends calibration periods for XCell Hydrogen Sulfide (H2S) and Carbon Monoxide (CO) gas sensors using Adaptive Environmental Compensation (AEC) algorithms.

Not only does TruCal compensate for environmental changes, it will let you know if the sensor inlet becomes blocked using an industry first - Diffusion Supervision technology.

Request a TruCal cost of ownership consultation to find out how much you can save.


How do you check the inlet of your H2S or CO sensor for blockage?

You perform frequent calibrations or bump tests (functional safety tests) to ensure gas can reach the sensor and is responsive.

How do users of MSA’s XCell H2S or CO sensor check if it is working?

They don’t - they rely on active testing and correction every 6 hours through Adaptive Environmental Compensation algorithms.

How do users of MSA’s XCell H2S or CO sensor check the inlet for blockage?

They don’t - they rely on the sensor to automatically check for blockages every 6 hours. This unique feature from MSA is called Diffusion Supervision.

TruCal now allows calibration periods to be extended to 2 years!

TruCal eliminates the need for regularly scheduled calibrations. Sensors will perform within stated performance specification for 24 months without manual calibration. This is based on test results from TruCal sensors exposed to all environmental elements. No calibrations have been conducted on any of these sensors for over 3 years!

Adaptive Environmental Compensation (AEC) has been testing the sensor every six hours and adjusting sensor response to account for changes in sensor response due to environmental conditions and sensor degradation. See the details and test data from our TruCal Whitepaper »

H2S Sensor Accuracy – Outdoor Testing w/o Calibrations
CO Sensor Accuracy – Outdoor Testing w/o Calibrations
Sensor Diffusion

Diffusion Supervision–Active Technology

Not only does TruCal compensate for environmental changes, it will let you know if the sensor inlet gets blocked using Diffusion Supervision technology. Diffusion Supervision employs proprietary acoustic mechanical design and algorithms to measure sound across the sensor's inlet. If the inlet is blocked with a material, like ice, the difference in the sound is detected and the unit is put into fault. When the obstruction is removed, Diffusion Supervision detects the clearance and returns to normal.

You'll achieve greater peace of mind knowing that TruCal's self-checking technology will let you know if gas can't reach the sensor. No more surprises when you go to calibrate the sensor only to find that it's been blocked for an unknown period of time. TruCal proactively self-checks every six hours!

TruCal saves time and money by doing the hard work for you

Extend Calibration Intervals

Up to 24 months

Validated performance

Know that the sensor works between calibrations

Automated Pulse Checks

Defined calibration periods are a thing of the past

Proactive Self-Checks

per day

Active Correction


  • Adjusts sensor readings due to environmental factors
  • Compensates for maturing sensor performance

Automatic Notifications


  • If sensor opening becomes blocked
  • When calibration is required
  • Sensor end-of-life is near

Found exclusively on the ULTIMA X5000 and General Monitors S5000 gas monitors

Available Downloads


When determining the total cost of ownership of your gas detection system, be sure to calculate installation, calibration, maintenance, and repair fees. Realize your savings below with our basic or advanced guide and see how MSA stacks up against any competitor. Calculate your savings here

Request a consultation

Download White Paper


How TruCal® technology lowers cost of ownership with improved sensor performance and less maintenance?

This whitepaper explains the latest developments in H2S and CO Electrochemical detection – the world’s first fail-safe self-calibrating sensors.

Download the White Paper