Thanks to
technological innovations, the food distribution industry has a greener way to
protect refrigerated food during transit: Nitrogen refrigeration. The existing
system relies on diesel-powdered mechanical refrigeration units.
Although these units are effective, they release significant levels of
noise and air pollution. While the new innovations decrease emissions to
safeguard the environment, there is a hidden health risk transportation
companies must take into account.
How Liquid Nitrogen Refrigeration Works
The new system uses a
liquid nitrogen system to cryogenically chill food. A storage
tank mounted underneath the truck can be easily refilled when empty. Since the
tank is stored outside the truck, the liquid nitrogen never comes into direct
contact with the food.
To cool the
refrigerated container, liquid nitrogen first passes through a heat
exchanger. As the nitrogen moves through the heat exchanger, it evaporates.
High-powered fans inside the container circulate the chilled air through the
compartment, helping keep all food safely chilled below the temperature danger
zone.
The traditional
mechanical refrigeration system emits significant noise while in operation.
Even when the truck itself is off, the refrigeration unit can cause as much as
80 dB of noise, which is roughly as much noise as a busy urban environment.
This noise level exceeds the typical noise pollution levels in cities, thus
limiting the hours when truckers can make deliveries. Additional downsides to
the mechanical refrigeration system include reliance on harmful
refrigeration chemicals and expensive maintenance and repair costs.
In contrast, the
liquid nitrogen system falls beneath the noise pollution thresholds, so
deliveries can be made at any time. This benefits both truckers and
restaurants, grocery stores, and other businesses who may want to accept
deliveries outside of business hours.
The liquid nitrogen
system, or N2 system, also reduces carbon dioxide emissions
significantly and does not use harmful refrigerants to keep food cool.
Transportation companies who want to green their image or offer their clients
increased flexibility will enjoy the liquid nitrogen refrigerant system for
these reasons.
While the cryogenic
system reduces costs and pollution associated with mechanical refrigeration,
the N2 system is not perfect. Liquid nitrogen does pose a safety risk if it
comes into contact with the food or the environment. If a truck rollover
accident caused a nitrogen spill, for example, individual health and
environmental dangers abound.
If the nitrogen gas
seeps into the load chamber in the accident, it could turn the truck chamber
into an oxygen deficient environment. Staff who opened the truck chamber to
check on their load could become dizzy, pass out, and die within minutes of
entering the oxygen deficient space.
The liquid nitrogen
itself has cryogenic properties, which is why it's been used to freeze off
cancerous cells and warts. A worker cleaning up the spill must take precautions
to avoid getting liquid nitrogen on their skin. In a worst-case scenario, an
employee could lose a finger if it was immersed in liquid nitrogen.
How to Safeguard Truckers Against Liquid Nitrogen Dangers
An O2 deficiency
monitor, also called an oxygen monitor, can protect employees from the dangers
posed by liquid nitrogen. These monitors continually measure the amount of
oxygen in the load chamber. When the cryogenic system is working properly,
oxygen will naturally remain at safe levels and the alarm will stay silent yet
vigilant. In the event that nitrogen gas leaks into the load chamber -- due to
a system malfunction or an accident - oxygen levels will start dropping. Once
the environmental oxygen levels falls below OSHA thresholds, the oxygen monitor
will flash and sound an alarm. This notifies staff that safety hazards exist,
so they will not open the load chamber and enter an oxygen deficient
environment.
Since staff can
succumb to asphyxiation within minutes, the O2 deficiency
monitor is necessary to monitor system performance and keep employees safe
if anything goes wrong. Since nitrogen is invisible and odorless,
employees have no other way to know whether the system's operating as it should
or whether there is an N2 leak.
Oxygen monitors from
PureAire use zirconium oxide sensors, which provide reliable service for 10+
years. To learn more about PureAire products, please visit
www.Pureairemonitoring.com.
