Copper Tube for R410

Produc t

Inform at ion

Copper Tube Tub e for R410A R410A We have recently been asked if our copper tube is suitable for use with R410A. Of course the answer is "YES" I am uncertain what has given rise to this question apart from the view that some air conditioning manufactures have expressed in that the tube should have a wall thickness of at least 1mm. This not the case if systems are designed in accordance with BS4434 : 1995 (EN378) since the basis of the pipe work design for any refrigeration or air conditioning system under this standard is centred around the maximum allowable pressure pressure of the refrigerant in the system, taking into account pressures that are experienced when the system is either in operation or at rest. There is also a minimum allowable pressure that systems must be capable of withstanding which is the saturation pressure of the refrigerant at the minimum system design temperature. This value in a 32  oC ambient temperature for R410A equates to 33.6bar for the high pressure side of a system and 19bar for the low pressure side. (heat pumps must be designed as if the entire system is at high side pressure). The charts below show the situation for an R410A system in a 32 oC ambient, together with an extract from our own copper tube maximum operating pressure chart.

HP swit switch ch sett settin ingg = 30.2 30.2ba barr

Pr Pres essu sure re reli relief ef valv valvee rati rating ng

(min (min allo allowa wabl blee pres presss x 0.9) 0.9)

(min (min allo allowa wabl blee pres presss x 1.1) 1.1)

R410A Minimum allowable pressure = 33.6bar

Strength test pressure = 43.68bar 

(des (desig ignn & leak leak test test pres pressu sure re))

(min (min allo allowa wabl blee pres presss x 1.3) 1.3)

Maximum Safe Working Pressure for Copper Refrigeration Tubes (Coil and Straight Lengths) Straight

Temperature = 50oC

Tem Tempera peratture ure = 100 100oC

Temperature = 150oC

OD

OD

Inch

mm

SWG

mm

X

1/8"

3.175

22

0.711

240

3478

230

3333

170

2463

X

3/16"

4.672

22

0.711

147.7

2140

141.6

2052

104.6

1516

X

1/4"

6.35

22

0.711

106.7

1546

102.2

1481

75.6

1095

HRP Standard Tube Coil

Wall Thickness

bar

psi

ba r

psi

bar

psi

X

5/16"

7.938

22

0.711

83.5

1210

80

1159

59.1

856

X

X

3/8"

9.525

21

0.813

77.5

1123

74.2

1075

54.9

796

X

X

1/2"

12.7

21

0.813

56.9

824

54.6

791

40.3

584

X

X

5/8"

15.875

20

0.914

51.8

751

49.6

719

36.7

532

X

3/4"

19.05

19

1.02

48.4

701

46.4

672

34.3

497

3/4"

19.05

18

1.22

58.4

846

56

811

41.4

600

7/8"

22.225

19

1.02

41.2

597

39.5

572

29.2

423

X X X

7/8"

22.225

18

1.22

49.6

719

47.5

688

35.1

509

X

1.1/8"

28.575

18

1.22

38.2

554

36.6

530

27

391

X

1.3/8"

34.925

18

1.22

31

449

29.7

430

22

319

X

1.5/8"

41.275

18

1.22

26.1

378

25

362

18.5

268

X

1.5/8"

41.275

16

1.63

35.5

514

34.1

494

25.2

365

The shaded area in the chart above shows the copper tube sizes that fall into the usable range for R410A based on heat pump application where the high pressure side of the system can be rated at a maximum of 100  oC and the maximum allowable pressure is 33.6bar, resulting in a test pressure of 43.68bar. We have also heard comments such that only hard drawn tube must be used, but since the pressure rating of coiled, half hard, and hard draw tube is calculated as the same value there seems to be no basis for making this assumption. One comment which may be worth considering is that fittings should be used as opposed to formed pipe bends which by their very nature have the potential of reducing the wall thickness and therefore the pressure capability of the tube.

Issue Date : 23rd October 2000

Issue No. 18