The use of HFC refrigerants and
Polyolester (POE) lubricants for airconditioning
and refrigeration have
generated new system chemistry related
problems. New and redesigned system
protectors have been developed to
counteract these problems and provide a
long, reliable life for the operating
refrigeration system.
Moisture is the major problem causing
contaminate for HFC/POE oil systems
just as it was for CFC and HCFC systems
using Mineral oil. Many HFC’s can hold
much more water than their CFC
counterparts but the oil differences are
much worse than those of the
refrigerant. POE oil can hold as much as
10 times more water than Mineral oils.
In addition, evacuation has proven
ineffective at removing this moisture so
a filter-drier is required to perform this
Water poses a new problem for POE oils
above and beyond those experienced
with Mineral oil. POE oil will react with
water to form organic acids at normal
operating conditions in refrigerating and
air-conditioning systems. This reaction
starts at water levels as low as 75 ppm.
These acids attack system components
including motor insulation and metallic
components reducing system life.
To combat the detrimental effects of
water in HFC and POE oil systems it is
imperative to hold moisture levels as
low as possible. It is generally accepted
that water level must be maintained less
than 50 ppm in the refrigerant and the
same for the oil. In order to monitor
system water level a moisture indicator
must be used that can sense changes in
moisture in this ppm range.
Many commercial sightglasses cannot
indicate a change at this level in liquid
lines that exceed 100°F. This means that
harmful organic acids may be attacking
system components while the indicator
is showing dry. The AMI has a unique
element that has the ability to change
color at low ppm levels so that proper
action can be taken before any system
components are damaged.
It was necessary to redesign standard
filter-driers for increased water removal
capacity to achieve these low moisture
levels. However, since no system is
entirely devoid of water upon startup
some organic acids will be generated
and must be removed. The desiccant
formulation for the EK and UDK series of
filter-driers was designed to provide the
optimal mix of water capacity and acid
capacity to ensure that both harmful
contaminates are effectively removed.
This desiccant mixture contains both
molecular sieve and activated alumina.
The molecular sieve is specifically
designed to provide maximum drying in
today’s systems. The activated alumina
is ideal for capturing the large organic
acids that the molecular sieve cannot.
Another aspect of POE oil is the ability to
keep more solid particles in suspension
than Mineral oil. This is particularly
important in retrofitted systems where
pockets of solid contamination are now
flushed from low flow areas and need to
be removed before moving parts in the
system are damaged. The filter-drier for
POE oils needs to have increased solid
particle holding capacity with minimal
impact to refrigerant flow capacity or
pressure drop.
HFC Refrigerants and
POE Lubricants
Figure 2. Acid generation in a 1.5 ton R-134a air-conditioning system
The filter-drier should also have
improved contaminate removal
efficiency as well to ensure that all
particles are captured the first time they
enter the filter-drier. The ability to
remove smaller particles is also
advantageous. The EK series filter-driers
provide a unique combination of these
characteristics to provide outstanding
filtration as shown in Figure 3.
The filter-driers for use in HFC and POE
oil systems must maintain the system
dry and free of any acids that may have
been generated. However, since water
capacity is of primary importance the
filter-drier should contain a higher
percentage of molecular sieve than was
required for CFC and HCFC systems. But
molecular sieve alone is insufficient
since it has virtually no organic acid
capacity. An organic acid removal
desiccant must be used such as
activated alumina to ensure low acid
levels are maintained. In addition, the
filter-drier should also have increased
filtration capacity and efficiency. The EK
series of filter-driers provides the optimal
combination of these properties to
ensure the long, trouble-free life of any
air-conditioning or refrigeration system.

 Figure 1.
 RSP-PRC022-EN 85
 Figure 4. Filtration capability of filter-driers
 Figure 3. Dry indication water level
 HFC Refrigerants and
 POE Lubricants
 The moisture indicating sightglass must
 also indicate moisture level in the range
 of less than 50 ppm moisture. Also, it
 must be able to perform this function at
 the temperature of the liquid line on
 which it is placed. Many sightglasses
 cannot perform this function at all liquid
 line temperatures. This low level
 indication ability is necessary to ensure
 that the system moisture never exceeds
 the level at which organic acid formation
 starts. The AMI moisture indicating
 sightglass provides this low level
 detection ability.

Universal Acid Test Kit
The Universal Acid Alert Test Kit
provides a positive indication of whether
the acid level of the refrigeration oil is
safe or unsafe.
For use with both Mineral and POE Oils!
• Quick and easy test kit
• Universal acid test kit for use with all
refrigeration lubricants
• By changing the percentage of oil
sample taken, the acid number of the
oil can be accurately determined
• Phase separation of the chemicals in
the kit provide a positive color change
regardless of the color and condition of
the oil
Ordering Information
Item # Description
KIT06815 AA Kit Universal
86 RSP-PRC022-EN
The application of air-cooled condensers
for year-round operation, or during
periods of low ambient temperatures,
requires some means of control to
maintain adequate condensing pressures
that ensure proper system performance.
It is essential that proper liquid refrigerant
pressure be controlled to:
1. Maintain liquid subcooling and prevent
liquid line flash gas.
2. Provide adequate pressure at the inlet
side of the Thermo Valve to obtain
sufficient pressure drop across the
valve port.
3. Properly operate systems with hot gas
defrost or hot gas bypass.
4. Provide adequate temperature for
operation of heat reclaim systems.
Without proper control of condensing
pressure, serious consequences in the
way of poor refrigeration and component
damage can occur. ALCO’s HeadMaster
Control offers an efficient and economical
approach to this common industry
problem on air cooled condensers.
The HeadMaster 3-Way Head Pressure
Control eliminates the need for special
piping or multiple control valves. As a
single unit it simplifies piping and
reduces installation costs.
Fundamentals of HeadMaster Head Pressure Controls
Figure 1: