Fisher & Paykel 635 Active Smart Service Manual Download

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13.5 Brazing Off The System

Brazing off a system that uses flammable refrigerant is no more dangerous than a brazing of a refrigeration
system that contains R12 that, when burnt, produces phosgene gas.

R600a will burn if it leaks from the system and is ignited.

Crimp-off pliers should be adjusted to prevent any leak. It is recommended that two pair of pliers are used
for the process.

Points to remember are:

•

Always work in a well-ventilated area.

•

Have your crimp-off pliers adjusted correctly.

•

Crimp the filter dryer process pipe off first.

•

Open the high side valve on the service manifold and allow liquid trapped in the high side hose to enter

the system, as this is part of the total refrigerant charge.

•

Disconnect the hose/fitting. Close the end of the tube and braze off.

•

Repeat the process on the compressor process pipe.

Should  the  system  be  undercharged  after  the  service  manifold  is  disconnected,  the  problem  could  have
arisen  from  the  fitting  of  a  line  tap  valve  to  the  process  pipe,  in  that  it  is  very  easy  to  introduce  non-
condensables  into  the  system  at  this  point  due  to  the  negative  pressure  in  the  compressor  shell.    The
practice of charging through line tap valves is not recommended.

As  the  amount  of  gas  needed  is  so  small  to  make  the  correction,  it  is  best  to  evacuate  and  recharge  the
system again with the correct charge.

13.6 Pressure Testing Of The Refrigeration System

CAUTION – R-600a REFRIGERANT (ISOBUTANE)

The refrigerant contained within the sealed in system is

flammable.

All care must be taken when servicing

these products.  Vent well before brazing.  Avoid any open flames or ignition source.  The gauges, charging
cylinder  and  other  such  equipment  used  with  R-600a  must  not  be  used  with  other  refrigerants  such  as
R-134a,  as  this  could  cause  cross  contamination  of  the oils used in the systems.  Gauges etc. should be
clearly marked to ensure that they are used only for R-600a refrigerant.

The use of the in-line pressure gauge can speed up and eliminate the incorrect diagnosis of a leak within a
refrigeration system.  In some cases it has been found to be the services manifold that was being used that
was leaking and not the system.  There are very few parts on the in-line pressure gauge that can leak.

Rule one:

In pressure testing any cabinet, before disconnecting any joint please be 100% sure that it is not the joint
that is at fault, otherwise a lot of time can be lost looking for a joint/leak that doesn't exist.

Rule two:

Only use dry nitrogen to pressure test a system.

NOT REFRIGERANT OR COMPRESSED AIR.

NEVER OXYGEN

Rule three:

Don’t over pressurise the system. It could be dangerous.

How to use the In-line Pressure Gauge:
Step 1:

Reclaim the refrigerant from the system (refer to Section 13.4) and purge the system with Dry Nitrogen.

Step 2:

Cut and connect the pipe circuit to be tested to the in-line pressure gauge and braze this joint.

Step 3:

At the other end of the pipe circuit being tested, crimp off the pipe with crimp off pliers and braze this end off
to totally seal the circuit.