Parker Hannifin PSG Combination Moisture Liquid Indicator User Manual
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PSG Combination
Moisture & Liquid Indicator
Catalog B-1, October 2007
Page 2 / Catalog B-1, PSG Moisture/Liquid Indicator
Parker PSG Moisture & Liquid Indicator
The Parker PSG Moisture and Liquid
Indicator combines the two functions
of moisture and liquid indication into
a single economical product. It takes
the guess work out of servicing refrigeration and air conditioning equipment.
The PSG assists the technician in determining the state of the circulating refrigerant at a particular location and if a safe
moisture level exists in the system. Excessive moisture in refrigerant systems
can cause unwanted chemistries such as
hydrolysis of lubricants and other materials, corrosion of metals, copper plating, ice formation at the metering device
and a chemical change in the motor insulation of a hermetic compressor.
8 Outstanding Benefits
One Indicator For All Refrigerants —
provides a true moisture indication for
Refrigerant 12, 134a, 22, 404A, 407C, 410A,
502 or 507.
Reliable And Accurately Calibrated Color
Change Points — calibration in parts per
million of moisture for each refrigerant. 3%
relative humidity indicator for CFC, HCFC,
and HFC, including R410A.
Replaceable Indicator Element — the color
indicator paper can be changed without removing the PSG from the line.
Indicator Protected From Discoloration
And Dirt — by a filter pad and screen. This
prevents washing of the indicator by the
refrigerant and protects it from system
contamination and turbulence.
Color Changes Are Easily Distinguished
And Reversible —
widely between the wet and dry condition,
there is no possibility of confusion. Colors reverse as often as moisture concentration in
the system changes.
indicator colors differ so
Plastic Cap — is supplied with PSG to keep
the glass free from dust, dirt and grease.
How It’s Made
The plated steel and copper ttings are
copper brazed to the heavily copper
plated steel body. A glass disc is inserted
in the body and heated, just to the melting point, under carefully controlled
conditions. This fuses the glass to the
body in a permanent leak-free joint. The
indicator paper (retained in a small brass
ferrule) is inserted from the back and
held in place with a slotted cylinder. The
slotted cylinder and indicator assembly
is mounted on a post that screws into
the bottom of the body, and seals with a
knife-edge joint. This overall construction is highly effective in preventing refrigerant leakage. The unit is painted to
protect it from corrosion.
Paper indicator elements are made in
the Parker laboratory under the strictest
quality control procedures. The indicator is tested for proper color change
ability in the laboratory and twice more
during assembly.
How It Works
The indicator is a porous lter paper
impregnated with a chemical salt that is
sensitive to moisture. The salt changes
color according to the moisture content
(relative saturation) in the refrigerant.
A dark blue color indicates the refrigerant is DRY and pink indicates a WET
condition. The indicator is formulated
so that it changes color at the moisture
levels generally accepted as the safe operating range.
Figure 1
The PSG calibration information in
Tables 1 and 2 is based on detailed
experimental data for Refrigerants 12,
22, 134a, 404A, 407C, 410A, 502 and
507. The PSG change points occur at
similar or lower moisture levels than
competing models promoted to have 3%
relative humidity indication.
For Air — Tests on air show that the PSG
changes color in the range of 0.5% to 2.0%
R.H. In ordinary air lines this means that the
PSG will change color at dew points in the
range of minus 40°F to -60°F (-40°C to -51°C).
Brazing
PSGs with 1/4” through 1-1/8” ODF
Solder connections are constructed with
long ttings made from either heavily
copper plated steel or copper. Both t-
ting types are suitable for soldering or
brazing using any of the common alloys,
such as silver solder, soft solder, StaBrite, or Sil-Fos or PhosCopper. PSGs
do not require disassembly in the eld
for brazing because the extended ttings
reduce the possibility of damaging the
moisture indicator element when the
PSG is brazed into the system. To prevent damaging the PSG, ensure ample
heat is supplied to the ttings and point
the torch tip away from the PSG body.
Proper brazing technique ensures proper
capillary action of the alloy.
The ODF Solder connections on the
PSG are clean when shipped. Polishing
the inside of the ttings before brazing is unnecessary, and could be harm-
ful on the copper plated steel ttings if
an excessive amount of copper plating
Large Full View Sight Glass — extra large
crystal clear sight glass for viewing the refrigerant. Bubbles indicate a shortage of
refrigerant or a restriction in the liquid line.
Disassembly For Installation Is Unnecessary
— with extended fittings on small size solder
models. PSGs are easy to braze.
Parker Hannifin Corporation, Climate and Industrial Controls Group, Cleveland, OH
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