Practice Piping Procedure - Mitsubishi Electric BDT CITY MULTI Installation And Pre-Commissioning Booklet

PRACTICE PIPING PROCEDURE [R410A]
01. PIPE RUN PLANNING
Planning of pipe runs should take into account the following criteria:
PIPE:
All pipe used in R410A installations is to comply with
AS/NZ Standard 1677 Part 2. Copper tube of the correct
wall thickness must be used.
SEALED PIPE:
Hard and soft drawn copper tube stored on site prior to
installation must have plastic end caps fitted to prevent
ingress of moisture and foreign objects. Bends and fittings
should be kept dry and in the original packing prior to
installation.
PENETRATIONS:
All building penetrations should be made in such a way that
the bare copper pipe does not contact the building fabric.
NOTE: Non-compliant pipe work will void the warranty.
02. NITROGEN PURGING
All brazing to be done with OFN (oxygen-free nitrogen) purging through the pipe work system.
Nitrogen should be circulated into the pipe work branches and are to be welded using a flow regulator. This prevents oxidation
of the inside of the pipe surface. This oxidation can block filters and LEV valve orifices, and cause oil contamination and
compressor failure.
ALL BRAZING MUST BE CARRIED OUT USING DRY NITROGEN PURGING.
NOTE: Failure to follow this guideline will void the warranty.
03. FLARE / FLANGE JOINTING PROCEDURE
R410A operates at much higher pressures than R22 and R407C refrigerants.
For this reason copper flare connection dimensions must meet the following criteria:
Nominal Diameter
1/4"
3/8"
1/2"
5/8"
3/4"
4
Outside Diameter R22/R407C
(mm)
mm across flare face
6.35
9.52
12.7
15.88
19.05
BENDS:
Minimise the number of bends. Ensure all soft drawn bends
are made with the correct size benders and are of full internal
diameter.
PIPE CLAMPS:
Ensure that the pipe work is fixed so there is no tension on
the indoor or outdoor unit connections. This can lead to stress
fractures at the flare/flange.
PIPE RUN LENGTHS:
Ensure the maximum pipe run lengths comply with system
specifications.
R410A
mm across flare face
9 9.1
13 13.2
16.2 16.6
19.4 19.7
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