Vaisala CO2 probes keep Woolies’ systems safe

Vaisala’s carbon dioxide probes have been employed widely across Woolworths Group stores to support the supermarket giant’s move to transcritical CO₂ refrigeration.

In Australia and New Zealand, the Group has embraced the adoption of CO₂ as part of its refrigeration technology. The natural refrigerant is known for its attributes as a low-GWP, non-toxic, non-flammable, odourless and colorless gas.

The shift towards CO₂ transcritical systems involve a significant capital outlay, which may limit the speed of implementation at other supermarkets, says Senior Commissioner at Woolworths, Luke Breeuwer.

“CO₂ refrigeration technology has improved markedly in recent years, which is enabling us to roll it out in most regions, except for parts of Queensland where humidity levels currently dictate the deployment of hybrid CO₂ systems,” he says.

“There is pressure from our finance department to push ahead with the new systems; not just to deliver environmental benefits, but also to ensure that at some point in the future, we are not left with refrigeration assets that cannot be maintained. The capital costs of the initiative are being offset by also utilising this technology for in-store heating.”

CO₂ monitoring is one of the critical aspects of operating the new refrigeration systems. High concentrations of the gas can cause unconsciousness and even death. Accurate, reliable monitoring is necessary for safety reasons and for the rapid detection of potential leaks.

Over the last eight years, Vaisala carbon dioxide probes have been performing that monitoring role. To protect the health and safety of customers, staff and contractors, outlets that use transcritical CO₂ refrigeration would typically require 24 sensors or more. A traditional store utilises around six CO₂ sensors.

HVAC solutions provider Emerson supplied many of the Woolworths stores’ refrigeration and HVAC control systems.

“Around 8 years ago we evaluated a locally sourced CO₂ sensor, but it suffered from quality issues and failures, so we equipped one store with the Vaisala sensors as a ‘proof of concept’,” says Senior Business Manager Cold Chain ANZ for Emerson, Shannon Lovett.

“Happily, the Vaisala probes performed extremely well, and have been rolled out in the Woolworths Group stores in Australia and New Zealand. We have also utilised Vaisala humidity and temperature sensors in a variety of similar applications. In comparison with some other CO₂ sensors, the Vaisala monitors were more expensive, but they were very popular with our contractors and we found that Vaisala’s product reliability lowered the cost of ownership.”

Breeuwer also sees the longer-term benefits of investing in higher quality instruments.

“The MODBUS communications capability of the Vaisala Indigo200 Transmitter with the GMP252 probe is also a major advantage for us; it means that the amount of wiring required is substantially reduced, which lowers both complexity and costs,” he says.

“We have large numbers of these sensors in operation but there have been no breakdowns or urgent call-outs, so the ongoing costs have been negligible. We are required to check sensor calibration every two years, but they are so stable that this check always shows the sensors to be within specification, which is great.”

The Vaisala CARBOCAP Carbon Dioxide Probe GMP252 is a carbon dioxide sensor designed for harsh and humid environments where stable and accurate CO₂ measurements are required.

“By utilising CO₂ in our refrigeration systems we are helping to lower greenhouse gas emissions whilst also lowering operational costs,” says Breeuwer.

“However, reliable CO₂ monitoring plays a vitally important role; protecting staff and the public, while helping to identify and reduce leakage – a win-win situation!”

Headquartered in Vantaa, Finland, Vaisala offers a range of observation products and services for applications in weather, environmental, and industrial measurements.