Safety Caution Concerned To New Refrigerant; Pipe Materials - Toshiba MMU-AP0072H2UL-1 Service Manual

• New Refrigerant (R410A)
This air conditioner adopts a new HFC type refrigerant (R410A) which does not deplete the ozone layer.

1. Safety Caution Concerned to New Refrigerant

The pressure of R410A is high 1.6 times of that of the former refrigerant (R22).
Accompanied with change of refrigerant, the refrigerating oil has been also changed.
Therefore, be sure that water, dust, the former refrigerant or the former refrigerating oil is not mixed into the
refrigerating cycle of the air conditioner with new refrigerant during installation work or service work.
If an incorrect work or incorrect service is performed, there is a possibility to cause a serious accident.
Use the tools and materials exclusive to R410A to purpose a safe work.
2. Cautions on Installation/Service
1) Do not mix the other refrigerant or refrigerating oil.
For the tools exclusive to R410A, shapes of all the joints including the service port differ from those of
the former refrigerant in order to prevent mixture of them.
2) As the use pressure of the new refrigerant is high, use material thickness of the pipe and tools which are
specified for R410A.
3) In the installation time, use clean pipe materials and work with great attention so that water and others
do not mix in because pipes are affected by impurities such as water, oxide scales, oil, etc.
Use the clean pipes.
Be sure to brazing with flowing nitrogen gas. (Never use gas other than nitrogen gas.)
4) For the ground protection, use a vacuum pump for air purge.
5) R410A refrigerant is azeotropic mixture type refrigerant.
Therefore use liquid type to charge the refrigerant. (If using gas for charging, composition of the
refrigerant changes and then characteristics of the air conditioner change.)

3. Pipe Materials

For the refrigerant pipes, copper pipe and joints are mainly used.
It is necessary to select the most appropriate pipes to conform to the standard.
Use clean material in which impurities adhere inside of pipe or joint to a minimum.
1) Copper pipe
<Piping>
The pipe thickness, flare finishing size, flare nut and others differ according to a refrigerant type.
When using a long copper pipe for R410A, it is recommended to select "Copper or copper-base pipe
without seam" and one with bonded oil amount 0.0001 lbs / 32' 10" (40mg / 10m) or less.
Also do not use crushed, deformed, discolored (especially inside) pipes.
(Impurities cause clogging of expansion valves and capillary tubes.)
<Flare nut>
Use the flare nuts which are attached to the air conditioner unit.
2) Joint
The flare joint and socket joint are used for joints of the copper pipe.
The joints are rarely used for installation of the air conditioner. However clear impurities when using them.
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