8 - SIZING THE REFRIGERANT PIPES WITH REFRIGERANT FOR LGNS
8.1 - General information and sizing limits
for the pipe system
Pipe sizing limits
LGN
Maximum
Linear length (discharge - liquid line), m
30
Height difference, m
12
The pipes must be as short as possible and have as few as
features, such as elbows, as possible to minimise the pressure
drops. For pipes which are at risk of being incorrectly used,
suitable measures (design, positioning, protection) must be taken
to prevent incorrect use.
The refrigerant pipes must be sized taking the following into
consideration.
Oil return is ensured by the drive principle. A minimum refrigerant
speed is required to ensure this drive. This speed depends on
the pipe diameter, the refrigerant and oil temperature (which, in
most cases, are treated as being the same).
Reducing the diameter of the pipes enables the refrigerant speed
to be increased. The minimum drive speed is not an issue for
pipes inside which refrigerant is in the liquid phase as the oil is
fully miscible.
Pressure drops at the compressor discharge (pipe joining the
evaporator outlet to the compressor intake) must be limited to
avoid reducing the performance of the system (increase in
absorbed power and decrease in cooling capacity).
Increasing the diameter of pipes limits pressure drops.
Pressure drops in the liquid pipe (joining the condenser outlet
to the expansion component) must not produce any phase
changes.
The estimation of these pressure drops must include those
created by any accessories, such as solenoid valves, filter dryers,
etc.
When used in low outdoor temperatures and long pipes, in order
to avoid poor supply to the system during the start-up phase,
the use of a check valve on the condenser outlet is recommended.
Select a non-sealed element in order to avoid the risk of an
excessively high pressure increase of the liquid refrigerant which
will be trapped between the solenoid valve (sealed) and this
valve.
8.2 - Sizing the pipes
The following procedure may be used to size the pipes:
-
Measure the length (in metres) of the pipe in question.
-
Add 50% to take the pipe's features into account.
-
Read the pipe size from tables 1 and 2 below.
-
Calculate the equivalent lengths of the components fitted onto the pipe in question (such as valves, filter, connections, etc.).
These equivalent lengths are generally available from the supplier of the components in question. Add these lengths to previously
calculated length.
-
Repeat steps 3 and 4 if necessary.
-
See the table below:
-
Discharge pipe* and liquid pipe*
Dynaciat LG/LGN
EN-40
Summary of Contents for DYNACIAT LG 080
Page 1: ...DYNACIAT LG LGN 07 2018 10188 Instruction manual...
Page 2: ...Dynaciat LG LGN EN 2...
Page 3: ...EN 3 Dynaciat LG LGN...
Page 67: ...EN 67 Dynaciat LG LGN...
