MCAC-VTSM-2011-09
Installation
90
Refrigerant Piping Installation
3.1.3.4. Opening bell-mouthed opening
1. Purpose: Flaring Bell-mouthed opening is used for screw thread connection.
2. Highlight:
1) Before performing the
Bell-mouthed opening operation, perform fire annealing for the hard pipe.
2) Use pipe cutter to cut pipe to ensure even cross section and avoid refrigerant leakage; do not use a
steel saw or metal cutting device to cut pipe, otherwise the cross section will get deformed and the
copper chip will enter the pipe.
3) Remove burr carefully to avoid scar on the bell-mouthed opening, which may lead to refrigerant
leakage.
4) When connecting pipes, use two spanners (one torque wrench and one non-adjustable spanner).
5) Before conducting opening bell-mouthed, install pipe onto the flaring nut.
6) Use proper torque to tighten the flaring nut.
Pipe
Diameter
Torque
Legend
(kgf-cm)
(N-cm)
1/4" (6. 35)
144~176
1420~1720
3/8" (9. 52)
333~407
3270~3990
1/2" (12. 7)
504~616
4950~6030
5/8" (15. 88)
630~770
6180~7540
3/4" (19. 05)
990~1210
9270~11860
Caution: When you are tightening the flaring nut with a spanner, the tightening torque will be suddenly
increased at a certain point. From this point, further tighten the flaring nut to the angles shown below.
Pipe Diameter
Angle of further tightening
Recommended length of tool lever
3/8" (9. 52)
60°~90°
About 200mm
1/2" (12. 7)
30°~60°
About 250mm
5/8" (15. 88)
30°~60°
About 300mm
7) Check whether the surface of the flaring opening is damaged. The size of the flaring opening is as
shown below.
Pipe Diameter
R410A
Legend
Size of Flaring Opening
(A)
1/4" (6. 35)
8. 7~9. 1
Spanner
tubing tie-in
torque spanner
Flaring opening nut
