What's New in Refrigeration
Have all the new
refrigerant laws left you out at sea?
reputation, reliability and maintainability of equipment normally improves with
age, but this has not been true when it comes to boat refrigeration. the 1990
Clean Air Act amendments imposed new regulations with landmark dates that
industry was unable to meet. So stop gap solutions and lack of time to do
research and development have resulted in a lack of standards and poor
information. With more than 12 new refrigerants on the market and 4 different
types of oils, it easy to get confused about which oil to use with which
refrigerant. A mismatch can not only affect the reliability of your system but
it can also destroy a system.
Although the automotive industry did agree
on a standard for the replacement refrigerant, HFC-134a,
also known as R134, they are not in
agreement on the type of oil that should be used with it. They also agreed on
use standards for labeling and service equipment and they have adapted a new
standard for service connectors that makes it difficult to make a mistake. These
standards are intended to prevent cross-contamination of gases and oils, but
these standards are not always followed through in boat refrigeration. All boat
refrigeration systems should be labeled for type of oil and viciosity and the
type of refrigerant used.
Cruising boats must be extra careful in
selecting a refrigerant as it might not be available in remote ports of call.
Below is a list of the
most commonly used oils in boat refrigeration.
is a wax free oil used for many years as a standard for
refrigeration. When it is mixed with Freon 12
it travels throughout the system, but it does not mix with
refrigerant oil is a synthetic
aromatic hydro-carbon. It is compatible with mineral oil and has
improved oil return over mineral.It can be used with most
refrigerants but NOT 134a. Almost all
NEW low temperature AC hermetic compressors are
serviced with Alkylbenzene oil.
oil must be used
with R134a refrigerant. This oil is compatible
and acceptable for use with R12, R22, and 502.
Most replacement engine drive systems come with this oil.
NOTE: Once a system has been set up to run on
Polyol Oil it can be switched back to Freon 12, but first you
must check with the manufacturer for approval.
is used in some new automobiles
but is NOT recommended in retrofits as it is
not compatible with other lubricants.
Most commonly used
refrigerants in new and retrofit systems.
is no longer
manufactured in the United States and is being phased out. Freon
12 is still available but its high cost is prohibitive.
is a long term
non-ozone depleting alternative refrigerant, but it is not a
direct replacement for R12.
Blends are a combination
of two or three refrigerants most of which contain Freon 22.
is also an ozone
depletor and has the same restrictions and regulations as
Freon 12. Although the production ban on it has been
postponed until the year 2020, but only certified technicians
can purchase any refrigerant that contains Freon.
blends that were developed to serve as a retrofit for
CFC 12. These refrigerants require Alkylbenzene oil.
Blends cause system high pressure
to run higher than R12. Blends also tend to separate into their
components which means that it may be necessary to remove and replace the entire
charge if a leak occurs and refrigerant is lost.
There are certain things
you need to do before adding refrigerant.
Things not to do.
Do not add
134a to any other refrigerant. The mixture
could become flammable or toxic. 134a can't be
used in a boat refrigeration system which uses either mineral or
alkybenzene. These will not mix with 134a and
will cause oil starvation resulting in compressor failure.
Don't change the
oil or refrigerant in a hermetically sealed compressor without
checking with the manufacturer of the compressor. Hermetically
sealed compressor motors and their wiring are submerged in the
refrigerant and oil mixture. The sysnthetic compounds may strip
the insulation off the wiring and cause damage to the
About five years ago there were concerns about converting to
134a. It was thought that the
and oil mixture would destroy the rubber "O" rings, the interior plastic and
elastomers parts and it was recommended that the oil should be flushed
completely from the system or down to only 1%. Now the common consensus is that
the Polyol Ester oil will mix with the mineral oil that is left in the system
and that the previous use of mineral oil would have sealed the hoses and "O"
rings thus preventing refrigerant leaks. After numerous tests by the
automotive industry and major oil companies the conversion procedures were
simplified to the following procedures.
Recover old refrigerant
Drain the oil from the compressor.
Replace the filter/dryers.
Add the correct amount of Polyol Ester oil.
Leak test the system Use a small amount of
refrigerant to pressurize to a pressure that is equal to the
ambient temperature. If nitrogen is available, pressurize to 150
PSI. Use no other gases such as oxygen for testing.
Deep Vacuum the system
(80% of the
Do a performance check.
134a service parts.
exposed "O" rings or seals with compatible 134a
134a has met the minimum safety requirements and that if you use other
refrigerant substitutes in your system your system will then become a test
Things you should know
Hermetically sealed boat
refrigeration units with all solid tubing rarely need servicing
and should be left with the original refrigerant since
R12 is still available although expensivve.
The conversion of belt driven
compressors or "Bolt Together" systems with seals are a problem.
These systems have a history of leaking and should be converted
whenever major overhaul of the system is required.