Installation - Emerson VSG Manual

PIPING
Before installing piping, the compressor inlet and
outlet ports should be inspected to ensure no dirt
is present.
Piping should be supported so that no piping loads
are transmitted to the compressor casings.
All piping should be inspected for cleanliness before
installation. As each pipe is connected to the com-
pressor, the coupling alignment should be checked
to ensure that no alteration has taken place.
If alignment has altered, the compressor is being
strained and the piping supports must be adjusted.
It is not sufficient merely to re-align the drive cou-
pling, as this will not correct the cause of the strain.
Compressors must have an inlet strainer perma-
nently fitted to the compressor inlet.
Care must be taken to avoid trapping the lines ex-
cept for specific purposes. When traps are used, the
horizontal dimensions should be as short as possible
to avoid excessive oil trapping.
Steel pipe is generally used in large installations
when joints are welded.
In making up joints for steel pipe, the following
procedures should be followed:
For threaded connections, all threads on the pipe
and fitting should be carefully cleaned to remove
all traces of grease or oil. Threads should then be
wiped dry with a lintless cloth. Only thread filling
compounds suitable for service should be used for
making steel pipe joints. These compounds should
be used sparingly, and on the pipe only. Do not put
any on the first two threads to prevent any of the
thread sealing compound from entering the piping
system. Acetylene or arc welding is frequently used
in making steel pipe joints, however, only a skilled
welder should attempt this kind of work. Take care
to see no foreign materials are left in the pipes and
remove all burrs formed when cutting pipe.
16

Installation

For halocarbon piping, only wrought copper fit-
tings should be used. Cast fittings as used for water
service are porous and will allow the refrigerant to
escape. Note this exception: In larger pipe sizes,
wrought fittings are not available. However, spe-
cially tested cast fittings are available and these may
be used with complete safety.
It is important to avoid short, rigid pipe lines that do
not allow any degree of flexibility. This must be done
to prevent vibration being transmitted through the
pipe lines to the buildings. One method of provid-
ing the needed flexibility to absorb the vibration is
to provide long lines that are broken by 90° Ells in
three directions.
A second method would be to install flexible pipe
couplings as close to the compressor unit as possible
with connections run in two different directions,
90° apart. These flexible connections should be
installed on both the high and low side lines of the
compressor unit.
Hangers and supports for coils and pipe lines should
receive careful attention. During prolonged op-
eration of the coils, they may become coated with
ice and frost, adding extra weight to the coil. The
hangers must have ample strength and be securely
anchored to withstand the vibration from the com-
pressor and adequately support the pipe lines.
This information is taken from and ANSI B31.3. The
installing contractor should be thoroughly familiar
with these codes, as well as any local codes.