• Colorimetric Gas Detection Improves Worker Productivity

Gas Detection

Colorimetric Gas Detection Improves Worker Productivity

Apr 09 2014

A large, global commercial refrigerated storage supply and integrator company with a production plant located in Northern England recently approached a1-cbiss to provide a fixed system for the monitoring of Toluene Diisocyanate (TDI).


The manufacturing plant offers a 'one-stop-shop' service, with the ability to deliver complete kitchen packages to large global restaurant chains. All equipment is designed, engineered and manufactured to exacting international standards on site.

As part of the manufacturing process spray flexible polyurethane foam is added to the refrigerated storage cabinets and as a by-product of this process, TDI fumes are created. Although the enclosed area is well ventilated and the employees are fully equipped with the adequate personal protective equipment, excess fumes may escape the foam production area and leak into the wider production area.

Prolonged exposure to concentrations of TDI can cause bronchial asthma and rapidly affect lung function. Short-term exposure to TDI can cause coughing, tightness of the chest, chest pains as well as skin irritation and eye irritation. 


As part of their previous safety program, employee protection in the production plant relied purely on human judgment, leading to low productivity and reduced production times. In addition, this 'monitoring' system lacked any way to provide an accurate representation of how much gas was leaking in coordination with EH40 guidelines.

The European Production and Health & Safety Manager began to look into a fixed gas detection system that could provide employee confidence by providing an alarm should TDI exposure reach exposure limits. It was at this point that a1-cbiss were referred to the company because of their gas detection expertise.


An a1-cbiss gas detection engineer went out to site to conduct a complete site survey and consider a number of parameters including; the location of the leak, the rate of gas leak, the direction it was leaking in, alarm thresholds and communication outputs.

The site survey deduced that two Dod ChemLogic Continuous Single Point Gas Monitors (CL1) which are single channel, self contained and complete continuous monitoring systems, would be needed to provide protection for the production area.

Utilising widely used and proven chemically impregnated, paper tape technology, the CL1 can provide detection of TDI’s at ppb levels. On detection of the target gas, a chemical reaction between the gas and tape creates a colour stain, which in turn is analysed by a sophisticated optical system, converting the colour stain into a ppb measurement.

a1-cbiss are experienced in system integration therefore we were able to send an installation team out to site to install the CL1 quickly and effectively in accordance with the sites safety needs.

Employee protection is of paramount importance, so alarm levels were planned in line with current EH40 guidelines for measuring TDI. The CL1 gas monitor was set to two independent alarm thresholds, which triggered a relay alarm once thresholds were reached.  The alarm was connected to a local beacon / sounder for local notification to production staff.

Since the installation of the CL1 gas monitor by a1-cbiss, the European Production and Health & Safety Manager is now confident that the production plant has an effective gas detection system in place to protect the production staff. 

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