Sterling VS - Manual (Page 7)

7
EXAMPLE: –
UNIT SIZE __________ 40
Steam Pressure ___10 PSI
Entering Air Temp. __ 40°F
I. CAPACITY
A. For 2 lbs. steam, 60°F entering air Read output directly from Table 3: 41,300 BTU/HR.
B. For higher steam pressures Multiply output from Table 3 by appropriate correction
and/or EAT’s above or below 60°F factor from Table 5 (below). 41,300 x 1.27 = 52,451 BTU/HR.
II. FINAL AIR TEMPERATURE
A. For 2 lbs. steam, 60°F entering air Read temperature directly from Table 3: 124°F.
B. For capacities calculated in IB (above) Output from IB
+ EAT = Final Air Temp
52,451
+ 40 = 121.0°F
1.085 x CFM from Table 3 1.085 x 595
III. FINAL AIR VOLUME Nom. CFM Final
A. For 2 lbs. steam, 60°F entering air 460 + Final Air Temp from Table 3 from = Air 460+124 x 595 = 655 CFM
530 Table 3 Volume 530
Nom. CFM Final
B. For fi nal air temperatures calculated 460 + Final Air Temp from IIB from = Air 460+121.0 x 595 = 652 CFM
In IIB (above) 530 Table 3 Volume 530
IV. CONDENSATE PER HOUR
A. For 2 lbs. steam, 60°F entering air Read lbs. per hour from Table 3: 43 LBS./HR.
B. For capacities calculated in IB (above) Output from IB
= lbs. per hour of condensate
52,451
= 55.0 LBS./HR.
Latent Heat From Table 6 953
STEAM PRESSURE IN LBS PER SQUARE INCH GAUGE
50 (344.7)
1.67
1.59
1.52
1.45
1.38
1.31
1.24
1.17
STEAM PRESSURE — LBS PER SQUARE INCH (SATURATED)
30° (-1°)
40° (4°)
50° (10°)
60° (16°)
70° (21°)
80° (27°)
90° (32°)
100° (38°)
40 (275.8)
1.61
1.53
1.46
1.39
1.32
1.25
1.18
1.11
75 (517.1)
1.79
1.71
1.64
1.57
1.49
1.42
1.36
1.29
30 (206.8)
1.53
1.46
1.39
1.32
1.25
1.18
1.11
1.04
20 (137.9)
1.45
1.37
1.30
1.23
1.16
1.09
1.02
0.96
15 (103.4)
1.40
1.32
1.25
1.18
1.11
1.04
0.97
0.90
5 (34.5)
1.27
1.20
1.12
1.05
0.98
0.91
0.85
0.78
2 (13.8)
1.22
1.15
1.07
1.00
0.93
0.86
0.80
0.73
ENTERING AIR
TEMPERATURE °F (°C) 10 (68.9)
1.34
1.27
1.19
1.12
1.05
0.98
0.91
0.85
TABLE 5 — STEAM CORRECTION FACTORS BASED ON 2 LBS. STEAM 60°F EAT
0 (.0)
1.18
1.11
1.03
0.96
0.90
0.83
0.76
0.69
40 (275.8)
286.7
(141.5)
920
(2140)
75 (517.1)
319.9
(159.9)
891
(2072)
50 (344.7)
297.7
(147.6)
912
(2121)
30 (206.8)
274.0
(134.4)
929
(2161)
20 (137.9)
258.8
(126.0)
940
(2186)
15 (103.4)
249.8
(121.0)
946
(2200)
5 (34.5)
227.1
(108.4)
961
(2235)
2 (13.8)
218.5
(103.6)
966
(2247)
10 (68.9)
239.4
(115.2)
953
(2217)
Steam
Temperature-°F (°C)
Latent Heat
of Steam-Btu/lbm (KJ/Kg)
0 (.0)
212.0
(100.0)
970
(2256)
TABLE 6 — PROPERTIES OF SATURATED STEAM
NOTE 1: Ratings apply only to free inlet and discharge
without diffusers.
NOTE 2: All motors are constant speed and operate
at top speed as indicated in motor data. Sizes 40
through 104 can be run at reduced speed with
addition of optional variable speed switch. This
switch is factory-calibrated for low and high speed
ratings, with intermediate speeds infi nitely controllable.
Sizes 164 through 700 operate at constant speed as
indicated in motor data.
NOTE 3: For specifi c motor data refer to motor
specifi cations in Tables 13 and 14.
NOTE 4: To correct for entering air temperatures, use 1°
temperature rise for each foot in mounting height. As an
example, 60°F air is required at work area (5 ft. above
fl oor) units are to be mounted at (20 ft.) above fl oor.
Mounting height (20 ft.) minus work height (5 ft.) equals
differential (15 ft.) or, 15° rise in air temperature at unit
air inlet. Correct for actual inlet air temperature of 75°F
(60°F + 15°F = 75°F EAT) on Table 5.
STEAM CALCULATIONS AND CORRECTION FACTORS
x
x