Carbon Dioxide and Oxygen Gas Detection in Laboratories

From flammable materials, trip hazards, and even biohazards – the laboratory can be a dangerous place. So, there are numerous aspects of risk minimization that must be examined in order to establish a workplace which is both safe, and compliant with health and safety legislation. A hazard which is common to a multitude of laboratory types, from the life sciences, physics research to chemistry departments, is posed by gases.

In the instance of substances like chlorine¹ and nitrogen oxides², which are corrosive and toxic, gases can be a chemical hazard in themselves. Check occupational exposure levels in HSE document EH40 or the supplied MSDS to ensure compliance with COSHH regulations.

Even seemingly innocuous gases, such as argon and nitrogen which are famous for being chemically inert, can instead become asphyxiation risks if leaks were to happen in poorly ventilated locations. ACOPs which have been published by bodies like the British Compressed Gases Association should be consulted.

The explosion/flammability risk is the other major category of risk posed by gas which is utilized in laboratories. Gases are usually kept in pressurized cylinders, and improper handling can lead to cylinder damage with sudden pressure discharge and explosions.³

A small spark from hot surfaces such as lab hot plates or electrical equipment such as vacuum gauges can be enough to start a fire. An oxygen leak causing localized oxygen enrichment will multiply the flammability risk massively.

These risks combined mean that it is crucial to be vigilant for gas leaks. This would involve the installation and maintenance of appropriate gas sensors, monitor and alarms to detect and alert of leaks in a laboratory setting, in addition to audible and visual alarms. Numerous alarm types cater for differing user requirements.

A hearing-impaired occupant may have to depend on visual alarms. Networked solutions, which are sometimes known as addressable systems, permit multiple devices as audible visual alarms, detectors, and shutdown interlocks to be installed efficiently, thus minimizing cabling. These systems allow continuous integrity checks at the same time, quickly alerting to any faults which may go hidden on older analogue type systems.

Safety First

Two gases which are commonly utilized that pose their own safety and detection challenges are carbon dioxide and oxygen. Since 2002 in Great Britain, both of these gases have been classed as ‘substances hazardous to health’.⁴ This means that for both short and long term exposure there are recommended workspace exposure limits and the installation of gas monitors is strongly recommended to ensure worker safety and compliance with exposure limits.⁵

It would be difficult to show compliance to COSHH requirements if you are not monitoring the environment for leaks. Additionally, HSE document EH40 not only lists occupational exposure levels but also the calculations needed to establish how long after exposure a person must recover in ‘clean’ air.

A lot of people wrongly assume that the main risk of carbon dioxide exposure is asphyxiation. Mistakenly, some people believe that in settings where oxygen and carbon dioxide monitoring are both needed, an oxygen depletion monitor is sufficient to cover both gases.

Yet, doing this is in violation of the safety standard BS EN 60079-29-2:2015⁶, which specifically states that, “where carbon dioxide levels need to be monitored for safety reasons, a dedicated CO₂ detector must be used.” This is because it is possible to go over safe CO₂ exposure limits still with sufficient oxygen concentrations that an oxygen depletion sensor would not trigger a warning.

International Gas Detector’s networked monitors are a simple and attractive solution, that compared to the industry standard, cuts down installation costs by 70% for practical solutions to monitoring. In addition to providing dedicated gas monitors, they also provide calibration and maintenance services to ensure optimum reliability and accuracy of monitors.⁷

Two Core Cable Solutions

Founded in 1917, International Gas Detectors brings over 100 years of expertise to the design of networked gas and safety systems. A number of the gas detectors are based upon the 2-Wire safe area addressable gas detection system which can detect more than 400 different gases.⁸ This system can be employed for a continuous gas level monitoring and has a unique design that makes it quick and easy to install.

These devices use addressable technology, which means they can be integrated with networked equipment or additional detectors. This includes devices such as International Gas Detector’s Room Status Indicators⁹ that can be installed outside the laboratory and possess a visual display which shows gas concentrations inside the lab and whether it is safe to enter. A single status indicator can display the output from up to eight other detectors and devices.

These devices possess one two-core cable for both power and communication due to the two-wire design. They have minimal cabling but provide maximum flexibility as the detectors themselves also possess interface points built in for other devices which gives them 80% more capability per detector than current standards.

These can include analogue signals, call points, relay interlocks and more. Additionally, it decreases the risk of wiring mistakes as the two-core cable connection has no specific polarity requirement.

Numerous detector monitoring, interlock and alarm solutions can be efficiently configured quickly. This makes the system particularly desirable where it is advised to have multiple detectors at different heights in the laboratory with gas interlocks, audible visual warnings, and secondary monitoring.

Integrated Safety

There are endless possibilities for devices which can be integrated with the two wire detectors. The detectors can also be integrated with International Gas Detector’s visual alarms,¹⁰ as audible-only alarms may not provide enough warning (for example in environments where ear protection is required), to ensure safe working areas.

The oxygen detectors provided by International Gas Detectors also boast enhanced product lifetimes. Industry standard lifetimes for oxygen sensors could only be two years. International Gas Detector’s oxygen sensors last over five years due to the utilization of new, reliable solid polymer technologies. Additional advantages include better reliability and accuracy, ensuring freedom from false alarms.

Each detector on the system can have its own individual alarms, up to three alarm points within its measured range. Creating networked pre-alarms and main safety alarms is possible by using this flexibility. These can be mapped to output devices that can warn of developing hazards as they evolve, instead of only sounding when situations have hit a critical level.

By utilizing modern digital systems, multiple controllers in an installation can network back to a main display panel (HMI). In addition to providing a main system overview, this main panel can also data log and generate up to the minute information over the internet.

This makes data available to anyone on site but also to anyone with an internet connection on any device type, tablet, phone, or PC. Connectivity is available 24 hours a day to administrators, operators, service and support people.

The flexibility of International Gas Detector’s devices and the significantly decreased installation costs mean it is affordable and simple to create custom, reliable, safety solutions for use in any working environment, from standard building blocks. With post-sales maintenance support and training opportunities for end users, either in-person or online, International Gas Detectors can help to ensure a safe workplace.

References

1. R. M. J. Withers and F. P. Lees, J. Hazard. Mater., 1985, 12, 231–282.
2. C. Arroyave and M. Morcillo, Corros. Sci., 1995, 37, 293–305.
3. R. M. Leslie and A. M. Birk, J. Hazard. Mater., 1991, 28, 329–365.
4. NIOSH Guidelines, https://www.cdc.gov/niosh/docs/76-194/default.html, (accessed March 2019)
5. HSE on CO₂, http://www.hse.gov.uk/carboncapture/carbondioxide.htm, (accessed March 2019)
6. BS EN 60079-29-2:2015, British Safety Standards Information, BSI, 2015
7. International Gas Detectors, https://www.internationalgasdetectors.com/about/, (accessed March 2019)
8. 2-wire Safe Area Gas Detector, https://www.internationalgasdetectors.com/products/2-wire-safe-area-gas-detector/, (accessed March 2019)
9. 2-wire Room Status Indication, https://www.internationalgasdetectors.com/products/new-2-wire-addressable-room-status-indicator/, (accessed March 2019)
10. Audible Visual Alarms, https://www.internationalgasdetectors.com/products/audible-visual-alarms/, (accessed March 2019)
11. Oxygen Detectors, https://www.internationalgasdetectors.com/gases/oxygen-depletion-monitors-and-oxygen-detection-solutions/, (accessed March 2019)