Sizing
to National Board
Convenient selector charts provide sizing to
meet the recommendations of the National Board.
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ASME
Code Rated Vessel
Each unit is stamped and registered in accordance
with the requirements of ASME Code Sec. VIII, Div. I.
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Stainless
Steel Wear Plate
Welded to the shell interior as provided on
all Penn tangential inlets prevents erosion of side wall.
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Controls
Thermal Pollution
Each blowdown accumulates in the bottom of
the tank to cool so that at the next blowdown the water mixes
and is cooled to drain.
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Quiet
Release of Steam
Vent sizes permit low velocity release of steam
to atmosphere additional vent appliances are not needed. Vent
noise level below 90 dB(A). |
A
PROVEN METHOD FOR BOILER BLOWOFF
NATIONAL
BOARD BOILER BLOWOFF
EQUIPMENT GENERAL RULES 1991 EDITION.
The blowdown from a boiler or boilers that enters a sanitary
sewer or discharges in an area which could be hazardous to
life or property should be controlled. This control should
be through some form of blowoff equipment which will reduce
the pressure and temperature to acceptable safe levels.
The blowdown vessel shall be of a volume equal to at least
twice the volume of one blowdown of the boiler when the normal
water level is reduced by not less than 4 inches. The pressure
of the blowdown when leaving any type of blowoff equipment
should not exceed 5 psig and the temperature of the drain
water should not exceed 140 deg. F. All materials used in
the fabrication of boiler blowoff equipment shall comply with
the requirements of Sec. VIII , Div. 1, Pressure Vessels and
Sec. II, Materials of the ASME Code. All blowoff equipment
shall have openings to facilitate cleaning and inspection. |
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Tank
Features
Penn Blowoff tanks come standard ASME Code Sec. VIII , Div. 1 designed
and stamped for 50 psig at 450
deg. F. and are of a welded construction from 3/8" thick carbon
steel materials. The tank would be fitted with
the following connections, a blowdown tangential inlet with stainless
steel wear plate, water overflow outlet
which extends to within 6" of the bottom of the tank, a 3/4"
siphon shall be located in the top portion of the
outlet pipe, and atmospheric steam vent. Couplings connections are
provided for a pressure gauge,
thermometer, level gauge, tank clean out drain, and cold water inlet.
The tank would be supported by a set
of four angle legs with floor pads. 36" diameter and smaller
tanks include couplings for inspection ports and
larger tanks include a 12" x 16" manway. For multiple
boilers, frequent blowdown, or addition of continuous
blowdown an optional drain aftercooler fitting with temperature
regulator valve can be provided to control
the condensate outlet to 140 Deg. F. to the drain. A level gauge,
thermometer, and pressure gauge can also
be supplied as an option. Penn Blowoff Tanks are completely welded
and assembled in Brookville,
Pennsylvania, USA using only new materials with a shop primer applied
to the exterior. Each unit is skidded
for shipment and carries a full year warranty against materials
and workmanship.
Size
Requirements
Tank size is very important for proper tank performance. The tank
selector chart and nozzle sizing charts
are based on the recommendations of the national board. The tank
is selected using the drum size, and the
nozzles are sized from the blowoff valve size and boiler operating
pressure. On multiple boilers the largest
drum and valve size should be used. Some states have special requirements
other than the recommendations
of the National Board. Please specify the State or Province the
tank will be used in.
Blowoff
Tank Sizing
- Calculate
the Cu. Ft. amount of blowout when lowering the Boiler Water Level
4". The
following formula should be used: Cu. Ft. of Blowoff = (4"/12")
X Drum Dia. Ft. X Drum
Length Ft.
- Select
a Blowoff Tank which has Cu. Ft. holding capacity equal to the
amount
calculated. If the amount of Blowoff is known select a tank with
that amount
holding capacity.
- Select
the drain and vent nozzles below using the Blowdown Valve Size
and Boiler
Operating Pressure. The inlet should be the same size as the Blowoff
Valve.
Blowoff
Tank Selector Chart
Tank
Cu. Ft. Holding Capacity |
Tank
Diameter |
Overall
Tank Height |
Tank
Total Cu. Ft. |
Tank
Total Gallons |
2.2
Cubic Feet
3.0 Cubic Feet
3.7 Cubic Feet
4.7 Cubic Feet
5.3 Cubic Feet
6.8 Cubic Feet
8.2 Cubic Feet
10.6 Cubic Feet
12.9 Cubic Feet
13.5 Cubic Feet
16.8 Cubic Feet
20.2 Cubic Feet
24.9 Cubic Feet
29.5 Cubic Feet
32.1 Cubic Feet
38.2 Cubic Feet
47.8 Cubic Feet
55.5 Cubic Feet
58.4 Cubic Feet
68.0 Cubic Feet
77.6 Cubic Feet
96.1 Cubic Feet
109.9 Cubic Feet
123.8 Cubic Feet |
18"
18"
20"
20"
24"
24"
30"
30"
30"
36"
36"
42"
42"
42"
48"
48"
54"
54"
60"
60"
60"
72"
72"
72" |
3'
4'
4'
5'
4'
5'
4'
5'
6'
5'
6'
5'
6'
7'
6'
7'
7'
8'
7'
8'
9'
8'
9'
10' |
4.4
6
7.4
9.4
10.6
13.6
16.5
21.1
25.8
26.9
33.6
40.5
49.8
59.1
64.3
76.5
95.6
111.1
116.9
136
155.2
192.1
219.8
247.5
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32.7
44.8
55.5
70.6
79.6
101.7
123.1
158
192.9
201.4
251.4
302.9
372.3
441.7
480.9
572
715.3
831
874.3
1017.5
1160.7
1437.3
1644.4
1851.5 |
Nozzle
Selector Chart
|
0-50
PSIG |
51-150
PSIG |
151-300
PSIG |
BDV
Size |
Inlet |
Drain |
Vent |
Inlet |
Drain |
Vent |
Inlet |
Drain |
Vent |
1" |
1" |
2
1/2" |
2
1/2" |
1" |
3" |
4" |
1" |
4" |
6" |
1
1/4" |
1
1/4" |
3" |
3" |
1
1/4" |
4" |
6" |
1
1/4" |
4" |
6" |
1
1/2" |
1
1/2" |
3" |
4" |
1
1/2" |
4" |
6" |
1
1/2" |
6" |
8" |
2" |
2" |
4" |
4" |
2" |
6" |
6" |
2" |
6" |
10" |
2
1/2" |
2
1/2" |
6" |
6" |
2
1/2" |
6" |
8" |
2
1/2" |
8" |
10" |
|
301-800
PSIG |
801-1200
PSIG |
1201-1600
PSIG |
BDV
Size |
Inlet |
Drain |
Vent |
Inlet |
Drain |
Vent |
Inlet |
Drain |
Vent |
1" |
1" |
3" |
6" |
1" |
4" |
8" |
1" |
4" |
10" |
1
1/4" |
1
1/4" |
6" |
10" |
1
1/4" |
6" |
12" |
1
1/4" |
6" |
12" |
1
1/2" |
1
1/2" |
6" |
10" |
1
1/2" |
6" |
12" |
1
1/2" |
6" |
14" |
2" |
2" |
6" |
14" |
2" |
8" |
16" |
2" |
8" |
18" |
2
1/2" |
2
1/2" |
8" |
16" |
2
1/2" |
8" |
20" |
2
1/2" |
8" |
24" |
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