Pressurized Tank Sizing (Bladder & Diaphragm):
The tank is charged to a pre-determined pressure resulting in Pa = Pf, thus:
Vt = EVs / (1-(Pf/Po))
Vt = Compression Tank Size (gal)
Vs = Total System Water Volume (gal) (in pipes, coils, etc.)
Pf = Minimum System Pressure (Fill Pressure, psia)
This is building static pressure over the tank +14.7 psia, atmospheric pressure + 5 psig for venting).
Po = Maximum System Pressure (relief Valve Pressure, psia)
E = Net Water Expansion Factor (Refer to Table 1 for water and Table 2 for glycol-water)
To use Table 1 and 2 the mean temperature is required (160-200℉ for hot water,100℉ for chilled water)
*The term of EVs is called Acceptance Volume. Vt is the Tank Volume.
Thank size must satisfy two conditions:
The volume of the tank must be large enough so that the system operates within the range of the fill pressure and the relief valve setting.
The tank’s Acceptance Volume must be at least as large as the system’s Expansion Volume.
|
Table 1
|
|
Temperature ℉
|
Factor
|
Temperature ℉
|
Factor
|
Temperature ℉
|
Factor
|
|
100
|
0.0057
|
155
|
0.0198
|
210
|
0.0391
|
|
105
|
0.0068
|
160
|
0.0208
|
215
|
0.0415
|
|
110
|
0.0080
|
165
|
0.0225
|
220
|
0.0433
|
|
115
|
0.0092
|
170
|
0.0243
|
225
|
0.0457
|
|
120
|
0.0097
|
175
|
0.0261
|
230
|
0.0475
|
|
125
|
0.0115
|
180
|
0.0279
|
235
|
0.0505
|
|
130
|
0.126
|
185
|
0.0296
|
240
|
0.0523
|
|
135
|
0.0138
|
190
|
0.0314
|
245
|
0.0547
|
|
140
|
0.0149
|
195
|
0.0332
|
250
|
0.0571
|
|
145
|
0.0167
|
200
|
0.0350
|
255
|
0.0595
|
|
150
|
0.0178
|
205
|
0.0374
|
|
|
|
Table 2 Temperature ℉
|
|
Type
|
% By volume
|
Approx. Freeze Temp.℉
|
100
|
110
|
120
|
130
|
140
|
150
|
160
|
180
|
200
|
220
|
240
|
250
|
|
Ethylene Glycol
|
10
20
30
40
50
|
25
16
4
-13
-35
|
1.70
1.75
1.96
2.06
2.24
|
1.47
1.54
1.68
1.77
1.91
|
1.46
1.51
1.66
1.75
1.88
|
1.31
1.38
1.49
1.56
1.67
|
1.28
1.29
1.38
1.45
1.55
|
1.24
1.29
1.38
1.45
1.55
|
1.20
1.25
1.35
1.41
1.49
|
1.13
1.18
1.25
1.31
1.38
|
1
1.15
1.22
1.27
1.34
|
1.08
1.12
1.18
1.23
1.29
|
1.06
1.10
1.15
1.20
1.25
|
1.05
1.09
1.14
1.19
1.24
|
|
Propylene Glycol
|
10
20
30
40
50
|
26
18
8
-7
-28
|
1.76
2.07
2.42
2.61
2.87
|
1.53
1.70
2.08
2.25
2.47
|
1.52
1.76
2.05
2.19
2.42
|
1.37
1.58
1.83
1.96
2.15
|
1.34
1.55
1.77
1.90
2.07
|
1.29
1.47
1.68
1.81
1.97
|
1.26
1.43
1.63
1.75
1.90
|
1.18
1.34
1.50
1.62
1.75
|
1.16
1.30
1.46
1.56
1.68
|
1.12
1.28
1.40
1.50
1.61
|
1.11
1.24
1.37
1.46
1.57
|
1.10
1.23
1.35
1.45
1.55
|
