installation manual

General Information

Liquid-cooled Generators

C = 11111 (for Natural Gas) or 3333 (for LP)

T = Temperature of the fuel into the fuel shut-off/regulator

Example 1: Determine the volumetric flow rate for a generator that requires 91.34 lb/hr of natural gas at 100% load.

Solution:

Specific gravity according to the local vendor: 0.5

Density of Natural Gas from Table 1: 0.0383 lb/ft3

Maximum Temperature of the fuel going into the generator: 90°F

C=11111 (for Natural Gas) from Equation 1

ν

=

Thus:

•

ν

=

And:

and

ν

•

= 2566 ft

3

/hr

ṁ = 91.34 lb/hr

p = 0.0383 -

(90-60)

—

11111

p = 0.0356 lb/ft

3



CALCULATING PIPE SIZE

Now that the volumetric flow rate has been identified, the minimum pipe size can be determined by using Table 2. This table is based on a specific gravity of 1.00 (specific gravity of air). For that reason, a correction is required when the fuel used has a different specific gravity. The fuel’s specific gravity can be obtained from the fuel supplier. The table is also based on a pressure drop of

0.3, which allows for a nominal amount of restrictions from bends, fittings, etc. Example 2 illustrates how to calculate the pipe size for the generator.

Example 2: Determine the iron pipe size for a generator that requires 2566 ft

3

/hr of Natural Gas. The unit is located 75 feet from the fuel source.

Solution:

Specific gravity of natural gas according to the local vendor: 0.5

Multiplier for the given specific gravity from Table 1: 1.1

According to Table 2, a 2-1/2 inch pipe will deliver 1750 ft^3/hr of air if it is located 75 feet from the fuel source. To determine the volumetric flow rate of natural gas, multiply the given flow rate by the multiplier (from Table 1).

Natural gas flow rate = air flow rate (ft

3

/hr) * Multiplier

= 1750 ft

3

/hr * 1.10

Natural gas flow rate = 1925 ft

3

/hr

Since the flow rate through a 2-1/2 inch iron pipe is less than the flow rate required by the generator (2430 ft

3

/hr), we must evaluate the next larger pipe (3 inches) by the same method.



TABLE 2

Length of Pipe

(In Feet)

120

150

180

210

240

270

300

450

600

60

75

90

105

15

30

45

1/2”

76

52

43

38 86

77

70

65

3/4”

172

120

99

120

109

100

92

173

155

141

131

1”

345

241

199

270

242

225

205

190

178

170

140

119

1-1/4”

750

535

435

380

345

310

285

320

300

285

270

226

192

Iron Pipe Size (IPS Inches)

1-1/2”

1220

850

700

2”

2480

1780

1475

2-1/2”

3850

2750

2300

610

545

490

450

420

380

350

1290

1120

1000

920

860

780

720

2000

1750

1560

1430

1340

1220

1120

660

620

580

545

450

390

1030

970

910

860

710

600

2300

2090

1950

1780

1680

1580

1490

1230

1030

3”

6500

4700

3900

3450

3000

2700

2450

13680

12240

11160

10330

9600

9000

8500

7000

6000

6”

38700

27370

23350

19330

17310

15800

14620

4800

4350

4000

3700

3490

3250

3000

2500

2130

4”

13880

9700

7900

6800

6000

5500

5100

27920

25000

22800

21100

19740

18610

17660

14420

12480

8”

79000

55850

45600

39500

35300

32250

29850

9

General Information

Liquid-cooled Generators



TABLE 3 — VAPOR CAPACITY OF PROPANE STORAGE TANKS

To Use: Go to the First column and pick the required kW load and then pick the minimum ambient temperature (40º, 20º or 0º F) that the generator would be operating in. The third column (tank capacity) will give the required tank size to continually produce the given fuel flow.

Max kW

Vapor

30

Minimum

Temp

40

Operating

Hours @

Max kW

24

Tank Capacity

(Gallons)

Length

Inches

Dia

Inches

Overall

Ht. Inches

20 20 35 120 57 24 33

10 0

40 35

67

26

25 20 36 150 68 24 33

12

60

0

40

72

26

40 20 38 250 94 30 39

20

80

0

40

74

26

50 20 40 325 119 30 39

25

100

0

40

77

31

60 20 51 500 119 37 46

30

150

100

50

170

120

60

0

40

20

0

40

20

0

100

35

53

105

36

51

103

850

1000

165

192

41

41

50

50

Propane storage tanks can provide either a liquid or a vapor supply to the generator. The above chart is for vapor withdrawal only and provides the kW output or amount of vapor that can be withdrawn at a given temperature while keeping the temperature of the liquid above the boiling point. If the withdrawal rate is too high, the LP temperature goes below the boiling point, the pressure drops to zero and no vapor can be withdrawn. A primary regulator is also required at the tank to reduce the line pressure to the generator to 5-14 inches of water column.

Propane Conversions: 36.38 ft

3

= 90,500 btu = 1 gal • 1lb = 21,500 btu = 8.56 ft

3

Figure 1.6 — Propane Storage Tank

10