2. What is Cryogenics?
Cryogenics is the science that addresses the production and effects of
very low temperatures.
The word originates from the Greek words 'kryos' meaning "frost" and
'genic' meaning "to produce”.
TYPES
Inert Gases: Inert gases do not react chemically to any great extent.
They do not burn or support combustion. Examples of this group are
nitrogen, helium, neon, argon and krypton.
FlammableGases: Some cryogenic liquids produce a gas that can burn in
air.The most common examples are hydrogen, methane and liquefied
natural gas.
Oxygen: Many materials considered as non-combustible can burn in the
presence of liquid oxygen. Organic materials can react explosively with
liquid oxygen.The hazards and handling precautions of liquid oxygen must
therefore be considered separately from other cryogenic liquids.
6. Role of Cryogenics in Food
Processing
perishable by nature.
require processing or preservation techniques to enhance the
storage life.
One such cryogen, liquid nitrogen (LN2) has a tremendous
potential to be used as a total loss refrigerant.( Liquid nitrogen is
nitrogen in a liquid state at an extremely low temperature.)
Only 10% of the installation capacity is required for maintaining
the desired temperature.
7. IN BAKERY AND PAKAGING
Cookies that take 13 minutes to cool from 130°F to 75°F
with conventional methods can be cooled in one minute
with liquid nitrogen.
ModifiedAtmosphere Packaging (MAP) and Controlled
Atmosphere Packaging (CAP) use a gas or a gas mixture
to maximize a food product’s shelf life, safety, purity and
freshness.
8. Food Freezing
To freeze a food, the product must first be cooled to the
transition point of water, 32°F (0°C), by placing the food in a
still-air freezer (sharp freezing), passing cold air over the
product (convection), bringing the food into contact with cold
plates (conduction), immersing it in a cryogenic fluid
(cryogenic) or using a combination of these processes
Cryogenic freezing is defined as freezing at -75°F (-59°C) or
below. High-velocity cryogen immediately impacts heat
transfer from product. Cryogen temperatures can reach as
low as -320°F, while overall internal freezer temperatures can
reach -150°F.
10. Are they dangerous?
Extreme Cold Hazard
Cryogenic liquids and their associated cold vapours and gases can produce effects on the
skin similar to a thermal burn. Brief exposures that would not affect skin on the face or hands
can damage delicate tissues such as the eyes. Prolonged exposure of the skin or contact with
cold surfaces can cause frostbite. The skin appears waxy yellow.There is no initial pain, but
there is intense pain when frozen tissue thaws.
Asphyxiation Hazard
When cryogenic liquids form a gas, the gas is very cold and usually heavier than air.This cold,
heavy gas does not disperse very well and can accumulate near the floor. Even if the gas is
non-toxic, it displaces air. When there is not enough air or oxygen, asphyxiation and death
can occur. Oxygen deficiency is a serious hazard in enclosed or confined spaces.
Toxic Hazards
For example, liquid carbon monoxide can release large quantities of carbon monoxide gas,
which can cause death almost immediately. Refer to the material safety data sheet for
information about the toxic hazards of a particular cryogen.
