Table 7-7. Blowdown Tank Size

TM 5-810-15

(1) Blowdown tanks will be designed and

R = Blowdown rate (pph)

constructed in accordance with the ASME Boiler

A = Predetermined bailer water concentration as total

and Pressure Vessel Code, Section VIII. The

solids (ppm)

amount of boiler blowdown capacity is determined

B = Total solids in feedwater to boiler (ppm)

to be a percentage of the boiler firing rate. The

Q = Steam output (pph)

percent of boiler blowdown is governed by the

allowable concentration ratio (CR) or the number

A boiler operated on exceptionally high quality

of times a dissolved solid may be concentrated over

feedwater will have very little blowdown. The size

the amount of dissolved solid in the feedwater. The

of the blowdown tank will be determined from

allowable concentration ratios are determined by a

table 7-7. Blowdown, steam and water connection

chemical analysis of the boiler feedwater and by the

sizes are shown in table 7-7. The tank will have

type of makeup water treatment. The continuous

openings to allow cleaning and inspection. The

blowdown rate can be determined using equation

blowdown tank should have a blowdown inlet

7-2:

connection, a water outlet connection, a vent con-

nection, a cold water supply line, a drain connec-

B

tion, a thermometer connection, and a pressure

R'

xQ

(eq 7-2)

A&B

gauge.

Table 7-7. Blowdown Tank Size.

Cold

Boiler

Steam

Water

**Blowdown

Design

*Blowdown

Vent

Inlet

Outlet

Tank

Pressure

Size

(psig)

(Inches)

(Dia x Ht.)

2

1

14" x 5'6"

1

2

1

14" x 5'6"

20

1

2

1

2

14" x 5'6"

to

1

2

1

2

14" x 5'6"

18" x 6*0"

50

2

3

2

4

2

4

2

4

20" x 6'0

2

1

14"

x 56"

x 5*6"

1

2

1

2

14"

x 6*0"

51

1

3

1

3

18"

x 6*0"

to

1

4

2

4

18"

x 6*0"

100

2

5

2

4

24"

x 6*6"

2

6

2

5

30"

14" x 5*6"

2

1

2

14" x 5*6"

1

3

1

3

20" x 6*0"

101

1

4

1

3

24" x 6*0"

to

1

5

2

4

33" x 6*0"

150

2

6

2

4

2

8

3

5

39" x 66"

14" x 5*6"

3

1

2

18" x 6*0"

1

4

1

2

24" x 6*0"

151

1

5

2

3

30" x 6*6"

to

1

6

2

4

39" x 6*6"

200

2

8

2

4

2

8

3

5

48" x 6'6"

4

1

2

18" x 60"

24" x 6*0"

1

5

1

2

30" x 6*6"

201

1

6

2

4

36" x 6*6"

to

1

6

2

4

48" x 6*6"

300

2

8

3

5

54" x 7*0"

2

10

3

6

20" x 6*0"

4

1

2

1

5

1

3

24" x 6'0"

33" x 6*6"

301

1

6

2

4

42" x 6*6"

to

1

8

2

4

54" x 7*0"

400

2

10

3

5

66" x 7*0"

2

10

4

6

7-9