Panasonic R410A service manual Tube diameter Tightening torque Tube thickness

Caution Before Connecting Tubes Tightly

(1)Apply a sealing cap or water-proof tape to prevent dust or water from entering the tubes before they are used.

(2)Be sure to apply refrigerant lubricant to the matching surfaces of the fl are and union before connecting them together. This is effective for reducing gas leaks. (Fig. 1-113)

(3)For proper connection, align the union tube and flare tube straight with each other, then screw on the fl are nut lightly at first to obtain a smooth match. (Fig. 1-114)

Adjust the shape of the liquid tube using a tube bender at the installation site and connect it to the liquid tubing side valve using a fl are.

Cautions During Brazing

Replace air inside the tube with nitrogen gas to prevent copper oxide film from forming during the brazing process. (Oxygen, carbon dioxide and Freon are not acceptable.)

1. Specifications

Apply refrigerant lubricant

Fig. 1-113

Union Flare nut

Fig. 1-114

Torque wrench

Do not allow the tubing to get too hot during brazing. The nitrogen gas inside the tubing may overheat, causing refrigerant system valves to become damaged. Therefore allow the tubing to cool when brazing.

Use a reducing valve for the nitrogen cylinder.

Do not use agents intended to prevent the formation of oxide film. These agents adversely affect the refrigerant and refrigerant oil, and may cause damage or malfunctions.

2. Connecting Tubing between Indoor and Outdoor Units

Spanner

Indoor unit

1

Outdoor unit

Fig. 1-115

(1) Tightly connect the indoor-side refrigerant tubing extended from the wall with the outdoor-side tubing.

(2) To fasten the fl are nuts, apply specifi ed torque as shown at right.

A

When removing the flare nuts from the tubing connections, or when tightening them after connecting the tubing, be sure to use 2 adjustable wrenches or spanners. (Fig. 1-115)

If the fl are nuts are over-tightened, the fl are may be damaged, which could result in refrigerant leakage and cause injury or asphyxiation to room occupants.

When removing or tightening the gas tube fl are nut, use 2 adjustable wrenches together: one at the gas tube fl are nut, and one at part A.

(Fig. 1-116)

For the flare nuts at tubing connections, be sure to use the fl are nuts that were supplied with the unit, or else fl are nuts for R410A (type 2). The refrigerant tubing that is used must be of the correct wall thickness as shown in the table at right.

		Fig. 1-116
Tube diameter	Tightening torque		Tube thickness
	(approximate)		(in.)
ø1/4" (6.35 mm)	120	– 160 in.lbs	t0.032
	(140	– 180 kgf · cm)
ø3/8" (9.52 mm)	300	– 360 in.lbs	t0.032
	(340	– 420 kgf · cm)
ø1/2" (12.7 mm)	430	– 480 in.lbs	t0.032
	(490	– 550 kgf · cm)
ø5/8" (15.88 mm)	590	– 710 in.lbs	t0.04
	(680	– 820 kgf · cm)

Because the pressure is approximately 1.6 times higher than conventional refrigerant pressure, the use of ordinary

flare nuts (type 1) or thin-walled tubes may result in tube rupture, injury, or asphyxiation caused by refrigerant leakage.

In order to prevent damage to the fl are caused by over-tightening of the fl are nuts, use the table above as a guide when tightening.

When tightening the fl are nut on the liquid tube, use an adjustable wrench with a nominal handle length of 7-7/8 in.

1-119