3

Minimum flow rate

Nominal

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

10

0.3

0.3

0.3

0.2

0.2

0.2

0.2

0.2

2.2

15

0.4

0.4

0.4

0.4

0.3

0.3

0.3

0.3

4.7

25

1.0

0.9

0.9

0.8

0.8

0.7

0.7

0.7

16

40

1.7

1.5

1.4

1.3

1.3

1.2

1.2

1.1

31

50

2.7

2.5

2.3

2.2

2.1

2.0

1.9

1.8

53

80

6.0

5.5

5.1

4.7

4.6

4.6

4.6

4.6

118

100

11

11

11

11

11

11

11

11

205

Specific

gravity

Max.

flow

rate

1235

10

15

20253040

10

0.3

0.4

0.6

1.1

15

0.4

1.2

1.8

2.9

25

1.8

5.9

40

2.8

6.5

14

50

3.6

7.1

15

24

80

11

16

26

38

100

14

21

28

45

55

Unmeasurable

Nominal

Kinem

atic

viscosity

For hatched area, retain Table A (according to specific gravity).

¡Gas

The flow rate range is indicated in actual base.

If the flow rate was given at standard status, be sure to convert it to actual flow rate and then, according to this table,

determine the flow rate range or nominal diameter.

Maximum

0.38

0.7

1.2

2.0

3.6

6

11

19

34

(60)

10

4.5

3.3

2.6

2.2

1.8

1.5

1.3

1.1

0.9

0.7

8.5

15

9.4

6.9

5.4

4.6

3.8

3.2

2.6

2.2

1.8

1.5

18

25

23

17

13

12

10

8

7

6

5

4

60

40

39

29

23

19

16

13

11

9

8

6

119

50

63

46

37

31

26

22

18

15

12

10

199

80

140

101

80

67

56

47

38

32

26

22

741

100

240

174

140

115

95

80

66

55

45

37

1280

Gas kind

Gas pressure MPa (gauge), temperature 20

°C

Reference: Gas viscosity

Argon

1.785

—

—

—

0.02

0.12

0.26

0.55

1.05

2

3.6

0.007 (mPa·s)

Air

1.293

—

—

0

0.07

0.20

0.4

0.85

1.5

2.7

—

0.017

Oxygen

1.429

—

—

0

0.05

0.17

0.35

0.75

1.35

2.5

4.4

0.0192

Carbon dioxide

1.977

—

—

—

0.01

0.1

0.23

0.5

0.95

1.7

3.3

0.0138

Nitrogen

1.251

—

—

—

0.07

0.21

0.42

0.85

1.55

2.8

—

0.0166

Nominal

Density

™Determination of minimum flow rate

In Table D, find a value that is nearest to and lower than

the pressure of gas desired, trace it upward in the same

column, and retain the value at the intersection with the

desired nominal diameter in Table C as minimum flow rate.

If it is necessary to exactly determine a minimum flow rate,

proceed to a calculation in the following manner.

Example 1

Suppose the fluid is air, the temperature 20

°C, the pres-

sure 0.5 MPa (gauge), and the nominal piping diameter

80 mm. How can the minimum flow rate nominal diam-

eter be found?

The minimum flow rate at nominal diameter of 80 mm at

air of 0.4 and 0.85 MPa in Table D is, according to Table

MPa, therefore, the minimum flow rate is, according to

interpolation,

Or the minimum flow rate can be obtained upon calcu-

lating an actual density.

Actual density

ρ of air at 20°C and 0.5 MPa is:

From Table C, the minimum flow rate at density of 6 and

the minimum flow rate is, according to interpolation,

Example 2

Suppose the fluid is carbon dioxide, the temperature 5

to 30

°C, the pressure 0.8 to 1.5 MPa, and the maximum

rate and the applicable nominal diameter be found? First

obtain the actual maximum flow rate, and then deter-

mine the nominal diameter. For calculating the maxi-

mum flow rate when the temperature and pressure have

ranges, retain the higher temperature and lower pres-

sure. Therefore, the actual maximum flow rate is:

Therefore, the nominal diameter is 40 mm. For obtain-

ing the minimum flow rate, retain the lower tempera-

ture and higher pressure.

From Tables C and D, the minimum flow rate at nominal

ing to interpolation,

Note: If the calculated result has a value below decimal point, truncate it

for maximum flow rate, or round it up for minimum flow rate.

Table A (according to specific gravity)

Table B (according to viscosity)

0.85-0.5

Qmin = 38+

× (47-38)

0.85-0.4

273.15

0.1013+0.5

ρ = 1.293 ××

273.15+20

0.1013

Qmin = 38+

× (47-38)

11-7.04

11-6

QMax. = 800

×

×

273.15

273.15+30

0.1013

0.1013+0.8

1.7-1.5

Qmin = 8+

1.7-0.95

FLOW RATE RANGE [Table1]

¡Liquid

Retain the minimum flow rate in Tables A (according to specific gravity) and B (according to viscosity), whichever is the

greater.