Hydrocarbons are highly flammable. Fortunately, the technology and the
expertise in working with flammable substances is readily available in
most parts of the world. The safety precautions required during the
cyclopentane foaming production, or hydrocarbon refrigerant charging,
are common knowledge and easily achievable through adequate safety
measures.
Hydrocarbon refrigerators are relatively new on the market. Initially, a
large portion of the production costs were related to safety measures
and the high costs of charging stations. Today, there is a second
generation of charging stations on the market, developed by the Danish
company A'Gramkow the world's largest producer of charging equipment for
hydrocarbons for the refrigeration industry. This new generation of
charging stations for hydrocarbons is considerably cheaper than earlier
systems, without relaxing the safety requirements. *
Safety concerns with respect to hydrocarbons in domestic fridges can be
dramatically overstated and appear to be raised mainly by HFC producers.
The charge in a domestic fridge is between 30 to 80 g, depending on
size, and even if the hermetically sealed system were to leak, a
significant portion of this charge would remain dissolved in the
mineral oil.
The German Safety and Standards Institution (TUV) has approved
'Greenfreeze' models as "safe and tested" and states that as a result of
their tests that "there are no dangers in the use, transport, and
storage of the refrigerator due to the use of liquid gas as a cooling
agent" and that "explosion of propane butane inside the refrigeratorcan
be practically excluded". Researchers at the Institute of Thermal
Engineering at Graz Technical University in Austria stated that
"changing from CFCs and HCFCs to flammable refrigerants like propane is
in fact not a problem of technology, it is mainly a problem of
regulations".
A recently revised British Standard allows use of up to 1.5 Kg of
hydrocarbons in sealed systems in any public area. Up to 10 Kg is
allowed in commercial and office spaces, and 25 Kg on industrial sites.
Upcoming changes in European Standard will increase the volume of
hydrocarbon refrigerant approved to be used, most likely along the lines
of the new British Standard.
In the US, the Underwriters Laboratory has approved the use of up to
115g of "higher inflammability" refrigerants such as propane. UL has
also approved the use of cyclopentane for foam insulation in a domestic
fridge. Use of hydrocarbons for automobile air conditioning in the US
currently requires an approval under the Significant New Alternatives
Programme (SNAP) on the basis of risk assessment.
The safety of hydrocarbon refrigeration results from the relative low
charge required to accomplish similar or better values than is needed by
CFC-12. This factor is taken into account not only in domestic
refrigeration, but also in mobile air conditioning, which by its nature
represents a greater risk. An Australian study to "Measure the Insurance
Risk of Hydrocarbon Refrigerants in Motor Cars" found that "only 40 per
cent of the mass [of hydrocarbons] is required compared to R12 or
R134a....[For] a medium sized Australian car the charge of hydrocarbon
is about 300g (10.6 oz.) the same as a large aerosol can." Furthermore,
the study concludes that "changing from R12 to saturated [hydrocarbon]
refrigerant increases the fire insurance risk [slightly] but reduces the
refrigerant loss and recovery risk...[so that] ...hydrocarbons reduce
the insurance risk by $2.30 /year." **
With respect to ammonia, often used as a commercial and industrial
refrigerant, a study of Norwegian refrigerant accidents concluded: "The
fatal accidents recorded are equally divided on ammonia and halocarbon
plants. Taking into consideration that by far greater number of large
refrigeration systems in the country, and all the older ones, are of
ammonia type, this implies that thisrefrigerant is probably the safer
choice.... The strong warning smell of ammonia is an invaluable asset."
***
One of the best ways to ensure safety around refrigerant use is to make
extra sure that the refrigerant does not leak in the first place.
Mayekawa in Japan, manufacturers of equipment for ammonia systems have
produced new large scale systems ( Mycom range) with a guarantee of
virtually zero leakage. These systems have been in production for
several years.
** Maclaine-cross, I.L.: School of Mechanical and Manufacturing Engineering: University of New South Wales, Australia: " Fireball, A Brief report on Pilot Experiments to Measure the Insurance Risk of Hydrocarbon Refrigerants in Motor Cars", January, 1993 [return]
*** Lorentzen, Gustav & Lunde, Helge: "Accidents and Critical Situations Due to Unintentional Escape of Refrigerants: A Survey of Cases in Norway over the Last Decades", Paper presented at the International Conference - New Applications of Natural Working Fluids in Refrigeration and Airconditioning, 10-13 May, 1994, Hannover, Germany. [return]