INSIDO 89980108 Instruction Manual Download

Page: 34 / 162

- 33 -

Ensure  that  the  detector  is  not  a  potential  source  of  ignition  and  is  suitable  for  the  refrigerant  used.  Leak
detection equipment  shall be  set  at  a percentage of the  LFL of the refrigerant and shall be  calibrated to the
refrigerant  employed  and  the  appropriate  percentage  of  gas  (25  %  maximum)  is  confirmed.  Leak  detection
fluids are suitable for use with most refrigerants but the use of detergents containing chlorine shall be avoided
as  the  chlorine  may  react  with  the  refrigerant  and  corrode  the  copper  pipe-work.  If  a  leak  is  suspected,  all
naked flames shall be removed/ extinguished. If a leakage of refrigerant is found which requires brazing, all of
the  refrigerant  shall be recovered from the system, or  isolated (by means of shut  off valves) in a part of the
system remote from the leak. Oxygen free nitrogen (OFN) shall then be purged through the system both before
and during the brazing process.

Removal and evacuation

When breaking into the refrigerant circuit to make repairs

–

or for any other purpose

–

conventional

procedures shall be used. However, it is important that best practice is followed since flammability is a
consideration. The following procedure shall be adhered to:

• Remove refrigerant;

• Purge the

circuit with inert gas;

• Evacuate;

• Purge again with inert gas;

• Ope

n the circuit by cutting or brazing.

The refrigerant charge shall be recovered into the correct recovery cylinders. The system shall be “flushed”

with  OFN  to  render  the  unit  safe.  This  process  may  need  to  be  repeated  several  times.  Compressed  air  or
oxygen shall not be used for this task. Flushing shall be achieved by breaking the vacuum in the system with
OFN  and  continuing  to  fill  until  the  working  pressure  is  achieved,  then  venting  to  atmosphere,  and  finally
pulling down to a vacuum. This process shall be repeated until no refrigerant is within the system. When the
final  OFN  charge  is  used,  the  system  shall  be  vented  down  to  atmospheric  pressure  to  enable  work  to  take
place. This operation is absolutely vital if brazing operations on the pipe-work are to take place. Ensure that the
outlet for the vacuum pump is not close to any ignition sources and there is ventilation available.

Charging procedures

In addition to conventional charging procedures, the following requirements shall be followed.

–

Ensure that contamination of different refrigerants does not occur when using charging equipment. Hoses or

lines shall be as short as possible to minimise the amount of refrigerant contained in them.

–

Cylinders shall be kept upright.

–

Ensure that the refrigeration system is earthed prior to charging the system with refrigerant.

–

Label the system when charging is complete (if not already).

–

Extreme care shall be taken not to overfill the refrigeration system.

Prior to recharging the system it shall be pressure tested with OFN. The system shall be leak tested on
completion of charging but prior to commissioning. A follow up leak test shall be carried out prior to leaving
the site.

9. Decommissioning

Before carrying out this procedure, it is essential that the technician is completely familiar with the equipment
and all its detail. It is recommended good practice that all refrigerants are recovered safely. Prior  to the task
being  carried  out,  an  oil  and  refrigerant  sample  shall  be  taken  in  case  analysis  is  required  prior  to re-use  of
reclaimed refrigerant. It is essential that electrical power is available before the task is commenced.
a) Become familiar with the equipment and its operation.
b) Isolate system electrically.
c) Before attempting the procedure ensure that: