TECHNICAL DATA
2” MoDEL G-2000 Dry vALvE
rISEr ASSEMBLy
Page 2 of 13
The viking Corporation, 210 N Industrial Park Drive, Hastings MI 49058
Telephone: 269-945-9501 Technical Services: 877-384-5464 Fax: 269-818-1680 Email: [email protected]
visit the viking website for the latest edition of this technical data page www.vikinggroupinc.com.
Form No. F_011110 17.04.27 Rev 17.1
B. Air Supply Design
Calculating Trip Pressure and Air Compressor Size
To calculate the point where the water pressure will overcome the air pressure and trip the valve, divide the static system water pres
-
sure by the differential (Approximately 5.75:1).
Example:
Static Water Pressure = 64 psi (4.4 bar) → Trip Point = 64 / 5.75 = 11 psi (0.76 bar).
The dry valve will trip when the air pressure is reduced to 11 psi (0.76 bar).
NFPA 13 requires that the air supply be capable of filling the entire sprinkler system to its required air pressure within 30 minutes. A
common method of sizing an air compressor is to use the following formula:
Compressor Size (cfm) = 0.012 x V (gal)
Where V = System volume and 0.012 is a common multiplier that will provide 40 psi (2.8 bar) in 30 minutes.
The following formula may be used for air pressures different than 40 psi (2.8 bar):
Where:
V = Volume
P = Required Air Pressure (Trip Pr 15 psi)
T = Fill time (typically 30 min.)
7.48 = gal. / ft.
3
14.7 = atmospheric pressure
Compressor
Size (cfm) =
V x P
7.48 x 14.7 x T
Example:
System volume as determined by table 1 = 750 gallons
System water pressure = 73 psi (5 bar)
Required air pressure = (73/5.75) + 15 = 28 psi (1.93 bar)
Compressor Size (cfm) =
(750 x 28)
= 6.4 cfm
7.48 x 14.7 x 30
Therefore, the compressor shall be capable of providing 7 cfm.
D. Pressure Switch Wiring;
Wire the Alarm Pressure Switch (PS10) and Air Superviso
-
ry Switch (PS40), and adjust pressure settings as shown in
Figures 3 - 5.
Table 1 - Pipe Capacity for Sizing Air Compressors
Pipe Diameter
Capacity
US
International
Schedule 40 (1” to 6”)
Schedule 30 (8”)
Schedule 10
Gal / Ft
L / m
Gal / Ft
L / m
1”
DN25
0.045
0.559
0.049
0.608
1-1/4”
DN32
0.078
0.969
0.085
1.043
1-1/2”
DN40
0.106
1.316
0.115
1.428
2”
DN50
0.174
2.161
0.190
2.360
2-1/2”
DN65
0.248
3.080
0.283
3.515
3”
DN80
0.383
4.756
0.434
5.390
3-1/2”
DN90
0.513
6.370
0.577
7.165
4”
DN100
0.660
8.196
0.740
9.190
5”
DN125
1.040
12.915
1.144
14.206
6”
DN150
1.501
18.640
1.649
20.477
8”
DN200
2.660
33.032
2.776
30.472
For Metric Units 1 Ft. = 0.3048 M, 1 Gal. = 3.785L
Table 2 - Air Pressure Settings
Maximum Water
Pressure
Air Pressure Setting
Minimum
Maximum
psi
bar
psi
bar
psi
bar
50
3.4
22
1.5
27
1.8
75
5.1
26
1.8
31
2.1
100
6.8
30
2.0
35
2.4
125
8.6
34
2.3
39
2.6
150
10.3
38
2.6
43
2.9
175
12.0
42
2.8
47
3.2
200
13.7
45
3.1
50
3.4
225
15.5
49
3.4
54
3.7
250
17.2
53
3.6
58
3.9
Supervisory Pressure Switch should be set 5 psi
(0.34 bar) below air compressor cut out.
Table 3 - Quick reference Compressor Size
Compressor
Size (HP)
Free Air @ 40 psi
(2.8 bar) (cfm)
Maximum Gallons in
System to Pump to 40 psi
(2.8 bar) in 30 Minutes
1/6
1.0
90
1/3
2.0
180
1/2
3.1
300
1
5.9
600
