Useful Engineering Data

Liquid Flow Formulae

Air Flow Formulae

Q=Cv x √(DP/d) or DP=d(Q/Cv)²

Where DP less than P1/2

Where DP equal to P1/2

Q=1.69Kv√(DPxP²)

Q = 0.84Kv x P1

Q = Flow L/Min

DP = Pressure Drop (Bar)

d = density i.e. Water = 1

Cv = flow factor coefficient of valve (L/Min)

(N.B. DP 5 - 10% is preferred)

Q = Flow (M³ Hr)

DP = Pressure Drop (Bar)

Kv = flow factor coefficient of valve (M³ Hr)

P1 = inlet pressure + 1 bar

P² = absolute downstream pressure = (inlet pressure + 1 bar - DP)

Saybolt Universal (seconds)

Engler (degrees)

Kinematic (centistokes)

Saybolt Universal (seconds)

Engler (degrees)

Kinematic (centistokes)

-

1.05*

1.5

103

3.0

21.3

PRESSURE

1 Bar = 14.5 PSI

1 Bar = 100 kPa (Kilopascal)

1 PSI = 6.9 kPa

1 Kg/cm² = 0.98 Bar

1 Atmosphere = 1.013 Bar

1 Inch Water gauge = 2.49 mbar

1 mm Mercury = 1.33 mbar

1 Ton / in² = 154 Bar

Volume

1 Gallon (UK) = 4.54 Litres

1 Gallon 9USA) = 3.79 Litres

1 Pint (UK) = 0.57 Litres

1 Pint (USA) = 0.47 Litres

1 Fluid Once (UK) = 28.4 cm³

1 Fluid Once (USA) = 29.6 cm³

FLOW

1 CFM = 0.472 Litres a second

1 CFM = 0.000472 m³/Sec

1 CFM = 28.32 Litres a minute

Temperature

From °F to C°

Add 40 then multiply by 5 then divide by 9 then -40

From C° to F°

Multiply by 9 then –40 divide by 5 then +40

Length

1 Inch = 25.4mm

1/16” Inch = 1.5875mm

1 foot = 0.305 Meters

1 Mile = 1.609 Kilometre

34

1.15*

2.5

109

3.2

22.8

37

1.25*

3.4

115

3.4

24.1

40

1.3*

4.2

125

3.7

26.7

42

1.4*

5.0

137

4.0

29.2

45

1.45*

5.7

148

4.3

31.7

50

1.6*

7.5

160

4.6

34.2

57

1.8*

9.4

171

4.9

36.8

62

1.9

11.0

183

5.2

39

68

2.1

12.6

205

5.9

44

74

2.2

14.2

242

7

50

79

2.4

15.5

256

7.3

55

85

2.6

17.0

285

8.1

62

92

2.7

18.6

313

8.9

68

98

2.9

20.0

342

9.8

74

Degrees Of Protection Provided By Electrical Enclosures (IP rating)

Definition

Test Type

2^nd No.

Definition

Test Type

1

Protected against objects Ø 50mm

Protect from access with hand

1

Protected against vertically falling water drops

2

Protected against objects Ø 12.5mm

Protected against access with finger

2

Protected against vertically falling water drops up to 15° inclination.

3

Protected against objects Ø 2.5mm

Protected against access with tool

3

Protected against vertically falling water drops up to 60° inclination.

4

Protected against objects Ø 1.0mm

Protected against access with wire

4

Protected against splashing water in any direction

5

Dust protected

5

Protected against water jets from any direction

6

Dust tight