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GENERAL FORMULAE

 

ENERGY AND TEMPERATURE

 

POWER

WATER PRESSURE

FLOW

VOLUME

AREA

DISTANCE

PRESSURE DROP ACROSS CONTROL VALVES

ELEVATION & CONDENSER SIZING

PIPE SIZE GUIDE C = 100

FRICTION LOSSES IN PIPE FITTINGS

ETHYLENE GLYCOL / PROPYLENE GLYCOL

PIPE SIZING GUIDELINES

COMMONLY USED FORMULAE AND CONSTANTS

TEMPERATURE CONVERSION

METRIC CONVERSION TABLE

PUMP OPERATION AT 50 Hz

   
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GENERAL FORMULAE

TONS OF REFRIGERATION

(GPM X DELTA WATER TEMP) / 24

AIR-SENSIBLE HEAT (BTUH)

CFM X 1.085 X (DRY BULB 1 - DRY BULB 2)

AIR-LATENT HEAT (BTUH)

CFM X 0.68 X (GRAINS 1 - GRAINS 2)

AIR-TOTAL HEAT (BTUH)

CFM X 4.5 X (ENTHALPY 1 - ENTHALPY 2)

HP - PUMP MOTORS

(US GPM X FT HD) / 
(3960 X PUMP EFFICIENCY)

HP - FAN MOTOR

(CFM X INCHES S.P.) / 
(6356 X STATIC EFFICIENCY)

TCU'S

LOAD + ( 0.5 TONS PER 3/4 HP ZONE)

RECTIFIERS

AMPS X VOLTS X 3.414 = BTUH

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ENERGY AND TEMPERATURE

1 TON REFRIGERATION

12,000 BTUH

1 TON COOLING TOWER

15,000 BTUH

 

0.293 WATTS

1 BTU

252 CALORIES

 

0.252 KG-CAL

-40 F

- 40 C

-30 F

-34.4 C

-20 F

-28.9 C

-10 F

-23.3 C

0 F

-17.8 C

10 F

-12.2 C

20 F

-6.7 C

30 F

-1.1 C

40 F

4.4 C

50 F

10 C

60 F

15.6 C

70 F

21.1 C

80 F

26.7 C

90 F

32.2 C

100 F

37.8 C

ENERGY AND TEMPERATURE

1 TON REFRIGERATION

12,000 BTUH

1 TON COOLING TOWER

15,000 BTUH

 

0.293 WATTS

1 BTU

252 CALORIES

 

0.252 KG-CAL

-40 F

- 40 C

-30 F

-34.4 C

-20 F

-28.9 C

-10 F

-23.3 C

0 F

-17.8 C

10 F

-12.2 C

20 F

-6.7 C

30 F

-1.1 C

40 F

4.4 C

50 F

10 C

60 F

15.6 C

70 F

21.1 C

80 F

26.7 C

90 F

32.2 C

100 F

37.8 C

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POWER

1 HP

2544 BTUH

746 WATTS

 

 

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WATER PRESSURE

1 PSI

2.31 FT HD

6.895< 10ˉ² BAR

6.8947 KILOPASCALS

2.036 INCHES OF MERCURY

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FLOW

1 US GPM

3.785 LITRES / MINUTE

227.1 LITRES / HOUR

0.2271 CU METRES / HOUR

 

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VOLUME

1 CU FT

7.481 US GALLONS
0.0283 CU METRES

1 CU METRE

35.31 CU FT
264.2 US GALLONS

1 US GALLON

3.785 LITRES
0.833 IMPERIAL GALLONS

2" DIA. PIPE

0.163 US GALLONS PER FT

2 1/2" DIA. PIPE

0.255 US GALLONS PER FT

3" DIA. PIPE

0.367 US GALLONS PER FT

4" DIA. PIPE

0.653 US GALLONS PER FT

6" DIA. PIPE

1.47 US GALLONS PER FT

8" DIA. PIPE

2.61 US GALLONS PER FT

10" DIA. PIPE

4.1 US GALLONS PER FT

12" DIA. PIPE

5.9 US GALLONS PER FT

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AREA

1 SQ FT

0.0929 SQ METRES

AREA OF A CIRCLE

(DIA X DIA) X 0.7854

CIRCUM OF A CYLINDER

DIAMETER X 3.1415

VOLUME OF A CYLINDER

(DIA X DIA) X
0.7854 X LENGTH

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DISTANCE

1 INCH

2.54 CM

1 FOOT

30.48 CM

1 YARD

0.9144 METRES

1 MILE

1.609 KILOMETRES

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                                                     PRESSURE DROP ACROSS CONTROL VALVES

                                            PSI PRESS DROP = (DESIGN GPM / VALVE CV) SQUARED

 

ELEVATION ABOVE SEALEVEL

DERATE CONDENSER BY

2,000 FT

0.96

4,000 FT

0.91

6,000 FT

0.87

8,000 FT

0.83

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PIPE SIZE GUIDE C = 100

PROCESS PIPING

TOWER RETURNS

PIPE
SIZE

FLOW
GPM

LOSSES
FT. PER
100 FT.

WATER
VELOCITY
FT./SEC.

FLOW
GPM

WATER
VELOCITY
FT./SEC.

1/2"

4

17

4.2

 

 

3/4"

9

19

5.4

 

 

1"

16

16.5

5.9

 

 

1 1/4"

26

10.3

5.6

 

 

1 1/2"

40

10.7

6.3

 

 

2"

75

10

7.2

 

 

2 1/2"

120

10

8

 

 

3"

210

9.7

9.1

90

3.9

4"

400

8.5

10.1

180

4.5

6"

960

5.7

10.7

510

5.7

8"

1800

4.8

11.6

900

5.8

10"

2700

3.3

11

1600

6.1

12"

3600

2.4

10.4

2400

6.9

14"

4500

2.3

10.7

3000

7.1

16"

5600

1.8

10.2

4000

7.3

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FRICTION LOSSES IN PIPE FITTINGS IN TERMS OF 
EQUIVALENT LENGTHS OF STRAIGHT PIPE

PIPE
SIZE

STD.
ELBOW

TEE
STRAIGHT
THRU

CHECK VALVE
PORT

BALL VALVE
(OPEN)

GATE VALVE
(OPEN)

1/2"

1.5

3

3.5

0.6

0.3

3/4"

2

4

5

0.8

0.5

1"

2.5

5.5

6

1

0.6

1 1/4"

3.5

7.5

9

1.2

0.8

1 1/2"

4.5

9

10

1.3

0.9

2"

5.5

12

13

1.5

1.1

2 1/2"

6.2

14

16

1.5

1.3

3"

8

16

20

2

1.6

4"

11

22

25

 

2.3

6"

16

32

40

 

3.5

8"

21

44

50

 

4.5

10"

26

55

65

 

6

12"

30

65

75

 

7

14"

35

80

90

 

8

16"

40

90

100

 

9

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ETHYLENE GLYCOL

PROPYLENE GLYCOL

PERCENT
VOLUME

FREEZE
POINT

SPECIFIC
HEAT

PERCENT
VOLUME

FREEZE
POINT

SPECIFIC
HEAT

10%

23F

0.957

10%

26F

0.98

20%

14F

0.924

20%

18F

0.96

30%

2F

0.897

30%

7F

0.935

40%

-13F

0.849

40%

-8F

0.895

50%

-36F

0.809

50%

-29F

0.85

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SIZING GUIDE LINES

                                   NOMINAL DESIGN FLOW

 

COOLING TOWER

= 4 GPM PER TON

CHILLING

= 2.7 GPM PER TON

                                 WEIGHED WATER TESTS 

 

( GPM X ∆ T  ) / 24 = CHILLER TON

( GPM X ∆ T  ) / 30 = TOWER TON

                       FT.HD = P.S.I. X 2.3

 

                                                  PIPE SIZING GUIDE Based on 10' HD loss/100' Pipe

½ =  2 GPM

2½ = 90 GPM

¾ =  5 GPM

3" = 160 GPM

1" = 10 GPM

4" = 320 GPM

1¼ = 20 GPM

5" = 600 GPM

1½ = 30 GPM

6" = 900 GPM

2" = 50 GPM

8" = 2000 GPM

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COMMONLY USED FORMULAE AND CONSTANTS

TONS =

( GPM X ∆ T  ) / 24

Nominal Tons

 

 

       

Pipe

CHW

 

 

 

Size

or

 

 

 

(Inches)

CTW

GPM

 

 

 

 

 

  GPM

= GALLONS PER MINUTE

1

3

10

  1 GAL

= 8.3#

1 ½

10

30

1 CU FT

= 7.5 GALLONS

2

17

50

  1 TON

= 12000 BTU/HR

2 ½

30

90

EWT °F

= ENTERING WATER TEMP °F

3

53

160

LWT °F

= LEAVING WATER TEMP °F

4

107

320

RISE °F

= LWT ― EWT

5

200

600

 

 

6

300

900

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TEMPERATURE

°F

°C

°F

°C

°F

°C

0

―17.8

7

―13.9

30

―1.1

1

―17.2

8

―13.3

35

1.7

2

―16.7

9

―12.8

40

4.4

3

―16.1

10

―12.2

45

7.2

4

―15.6

15

― 9.4

50

10.0

5

 ―15

20

― 6.7

55

12.8

6

―14.4

25

― 3.9

60

15.6

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METRIC CONVERSION TABLE

To Convert

 

Multiply

To Convert

 

Multiply

from

To

by

from

To

by

To Convert

 

 

Power

 

 

US gpm

liters/min

3.785

ft-lb/sec

watts

1.356

US gpm

liters/hr

227.1

hp

watts

745.7

US gpm

cu m/hr

0.2271

hp

kw

0.7457

cfm

liters/min

28.317

hp

cheval-vap

1.0139

cfm

cu m/min

0.02832

 

 

 

cfm

cu m/hr

1.6992

 

 

 

Unit Weight

 

 

Heat

 

 

lb/ft

kg/m

1.4881

Btu

gr-cal

252

lb/sq in

gr/sq cm

70.31

Btu

kg-cal

0.252

lb/sq in

kg/sq cm

0.07031

Btu/lb

kg-cal/kg

0.5556

lb/cu in

gr/cu cum

27.68

Btu/sq ft

gr-cal/sq cm

0.2713

lb/cu ft

kg/cu m

16.018

Btu/cu ft

kg-cal/cu m

8.899

Length

 

 

Weight

 

 

inches

mm

25.40

grains

grams

0.0648

inches

cm

2.540

ounces

grams

28.350

inches

meters

0.0254

ounces

kg

0.02835

feet

meters

0.3048

pounds

kg

0.4536

feet

km

0.0003048

pounds

tonnes

0.000454

yards

meters

0.9144

US tons

kg

907.2

yards

km

0.0009144

US tons

tonnes

0.9072

miles

km

1.609

long tons

kg

1016

 

 

 

long tons

tonnes

1.0160

Volume

 

 

Area

 

 

cu inches

cu cm

16.387

sq inches

sq mm

645.2

cu inches

 liters

0.01639

sq inches

sq cm

6.452

cu feet

cu meters

0.02832

sq feet

sq meters

0.09290

cu feet

liters

28.317

sq yards

sq meters

0.8361

cu yards

cu meters

0.7646

sq miles

sq km

2.590

fl ounces

cu cum

29.57

acres

hectare

0.4047

US gal

cu meters

0.003785

 

 

 

US gal

liters

3.785

 

 

 

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PUMP OPERATION AT 50 HZ

60 HERTZ

50 HERTZ OPERATION

GPM

X 0.833 (17%)

HEAD

X 0.694(31%)

B.H.P.

X 0.58 (43%)

3500 RPM

2900 RPM

1750 RPM

1450 RPM