Hitachi CENTRIFUGAL VRF RASC-HNPE Serie Manual De Instrucciones página 21

REFRIGERANT PIPING & REFRIGERANT CHARGE
8.2 PIPING CONNECTION FOR RASC UNIT
Gas pipe accessory (Only for RASC-(8/10)HNPE)
The gas pipe accessory (factory-supplied silencer) shall be
brazed to the field supplied gas line, and connected to the gas
valve as indicated in the drawing:
The stop valves are located on the right side of unit cover.
Before connecting refrigerant piping, the stop valve protection
cover shall be removed.
1 Mount the piping cover in order to avoid water entering into
the unit. Seal the holes where pipes and wires are inserted,
by using a insulation (field-supplied).
2 If the field-supplied piping is connected with stop valves
directly, it is recommended use a tube bender.
3 Check to ensure that the stop valves are closed completely
before connecting pipes.
4 Connect the field supplied refrigerant pipes to the indoor unit
and RASC unit. Apply the oil thinly at the seat flare nut and
pipe before tightening.
5 After connecting the refrigerant piping, seal the open space
between knockout hole and refrigerant pipes by using
insulation material.
6 Operation of stop valve should be performed according to
the figure below.
8.3 BRAZING WORK
!
C A U T I O N
• Use nitrogen gas for blowing during pipe brazing. If oxygen, acetylene
or fluorocarbon gas is used, it will cause an explosion or poisonous
gas.
11 PMML0399B rev.0 - 11/2015
Spindle Type
Spindle valve

Flare nut

Cap

Check joint for service port

Closed upon factory shipping
Liquid valve
Gas valve
Gas valve
Do not apply two
spanners at this
position. If applied,
Liquid
valve
leakage will occur
Do not work
with two
spanners here.
Refrigerant
leakage shall
occur
Spindle type
!
C A U T I O N
• At the test run, fully open the spindle and ball stop valve.
• If not fully opened, the devices will be damaged.
• Do not attempt to turn service valve rod beyond its stop.
• Do not loosen the stop ring. If the stop ring is loosened, it is dangerous
since the spindle will hop out.
• An excess or a shortage of refrigerant is the main cause of trouble
to the units. Charge the correct refrigerant quantity according to the
description of label at the inside of service cover.
• Check for refrigerant leakage in detail. If a large refrigerant leakage
occurs, it will cause difficulty with breathing or harmful gases would
occur if a fire was being used in the room.
• A lot of oxidation film will occur inside of tubes if no nitrogen gas
blowing is performed during brazing work. This film will be flecked
off after operation and will circulate in the cycle, resulting in clogged
expansion valves, etc. This will cause bad influence to the compressor.
• Use a reducer valve when nitrogen gas blowing is performed during
brazing. The gas pressure should be maintained within 0.03 to 0.05
MPa. If a excessively high pressure is applied to a pipe, it will cause
an explosion.
RASC unit stop valve
Liquid
Tightening Torque (N.m)
 
40
7-9
10HP: 60
80
-
8/10HP: 100
Stop valve
(Spindle type)
Flare nut
Use two spanners
Don not apply two here for pipe
spanners work here
connection
Position to apply
spanners
Ball type
Ball Type
Gas
(a)
 
33-42
14-18
20-25