By Jim Parsnow
The marketing hype continues on "alternative refrigerants". Driven by the Montreal
Protocol and Federal laws like the U.S. Clean Air Act, the market potential for replacement
or alternative refrigerants is an opportunity for an array of chemical companies to promote the "drop-in answer to your refrigerant needs". Unfortunately the public
is being tasked with finding the right answer to their particular needs, and they
are becoming increasingly confused by the advertisements and misleading promotions.
If the general public were well versed in chemistry, perhaps the alternative refrigerant
choices would be easier to sort. However, most of the people who are faced with
these choices are not chemists, but auto mechanics, service technicians, facility
managers, property managers, engineers and numerous other professions who are addressing
a mechanical device that uses refrigerants. Even environmentalists have been misled
by the alternative refrigerant choices.
The following three questions should be considered to properly determine the best
application of alternative refrigerants. They will help to sort the hype from good
information.
Standard ASHRAE 34, Number Designation and Safety Classification of Refrigerants provides
a uniform rating of refrigerants for toxicity and flammability and also assigns refrigerant
numbers (e.g. R-11, R-12, R-22, R-134a). Standard ASHRAE 15, Safety Code For Mechanical Refrigeration Rooms establishes safe practices in designing and installing
equipment.
These standards provide factual data to sort out the marketing hype. Under ASHRAE
34, refrigerants assigned a number will also be listed as to flammability and toxicity.
Flammability is tested according to the American Society of Testing Materials
(ASTM) E-681 and the refrigerant is assigned to one of three categories: 1 - no flame
propagation; 2 - low flammability or 3 - high flammability.
For example, under ASHRAE 34, HFC-134a is classified in group 1, no flame propagation,
because it is not flammable at any concentration in air at atmospheric pressure.
On the other hand alternative refrigerants referred to as hydrocarbons ignite at
concentrations as low as 2% by volume and are assigned to group 3. There are also two classifications
for toxicity, "A" or "B". The "A" designates lower toxicity and the "B" higher
toxicity. These designations are applied with the numbers (e.g. A1, B1) to provide the complete safety classification as noted in fig. #1. For example: CFC-11,
12 and HFC-134a are classified A1, no flame propagation, lower toxicity, HCFC-123
is assigned B1, no flame propagation, higher toxicity.
Blended refrigerants are assigned dual classifications, the first represents the safety
classification for the refrigerant blend as it is purchased while the second represents
the worst case that could be encountered if the components should separate during operation or during a leak. For example, R-410a (HFC32/125, 50%/50%) has been assigned
a A1/A1, designation - no flame propagation, lower toxicity. Those blended refrigerants
that contain hydrocarbons or other flammable components may have two different ratings depending on the potential for flammability during applications. For example:
R-406a HCFC-22/isobutane 600a/HCFC-142b, 55%/4%/41% is classified as a A1/A2, non-flammable
as originally formulated, but could become flammable in application, such as a leak. Under ASHRAE Standard 15, this refrigerant would have to be applied per
the worst condition A2. As a result under ASHRAE 15 Safety Code, R-406a would not
be allowed for comfort cooling applications.
The assignment of an ASHRAE refrigerant designation has other benefits in that the
number serves as a generic reference to the refrigerant rather than a manufacturers
trade name. For example, R-134a is sold by Dupont under the brand name SUVA MP.
Allied Signal refers to R-134a as Genetron 134a. In both cases, R-134a is the same.
Other industrial standards produced by the Air-Conditioning and Refrigeration Institute
(ARI) provide guidance and in some cases are adopted by law. For example, ARI 700-95
is Specifications For Fluorocarbon and Other Refrigerants. Reclaimed refrigerants both in motor vehicles and stationary/commercial sectors must meet the requirements
of ARI Standard 700 under the Clean Air Act Section 608. ARI Standard 700 specifies
acceptable levels of refrigerant purity for fluorocarbon refrigerants. EPA is also
considering an update to the Clean Air Act to incorporate another industry publication:
Industry Recycling Guide (IRG-2). IRG-2 still refers to ARI 700 as the purity level
standard.
Two other standards that should be reviewed are ASHRAE Guideline "K" Containers For
Recovered Fluorocarbon Refrigerants and Guideline "N", Assignment Of Refrigerant
Container Colors. All refrigerants are assigned a container color so that when in
stock they can easily be distinguished from other type. For example, HFC-134a in cylinders
is designated by light blue(sky). Guideline K is important as it references the
proper markings that should be labeled on all refrigerant containers along with reference
to Department of Transportation requirements for refrigerant containers.
ESSENTIAL REFERENCES Guideline Standards | |
ASHRAE 34-1992: | Number designation and safety classification of refrigerants |
ASHRAE 15-1994: | Safety code for mechanical refrigeration |
ARI 740-93: | Performance of refrigerant recovery, recycling, and/or reclaiming equipment |
ARI 700-95: | Specifications for fluorocarbon refrigerants |
ASHRAE Guideline "K": | Containers for recovered fluorocarbon refrigerants |
ASHRAE Guideline "N": | Assignment of refrigerant container colors |
U.S. EPA Guidelines & Law: | Clean Air Act;, final ruling of Section 608 of CAA; dated May 14, 1993; EPA Section 114 Letter; EPA Action Guidelines |
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