Hach sc200, User Manual

Page: 568 / 875

6
S E L E C T I N G A U N I T H E A T E R F O R U S E W I T H S T E A M
DESIGN CONDITIONS
— Heating load = 139 MBH
— Entering air temperature (EAT) = 70°F
— Steam pressure = 10 PSIG
— Mounting height = 30 feet
— Standard vertical projection steam unit required (Model VS).
SELECTION PROCEDURE
1) Calculate equivalent capacity at conditions of Table 4.
Capacity required
Equivalent capacity = ————————
Factor (Table 5)
139
= ——— = 134 MBH
1.04
From Table 4, select Cat. No. VS-137 unit heater.
2) Calculate unit capacity at actual conditions.
Actual capacity = MBH (Table 4) x Factor (Table 5)
= 137 x 1.04 = 142.4 MBH
3) Calculate weight of condensate in pounds per hour.
Actual BTUH
Pounds of condensate = ——————————
Latent heat (Table 5)
142,400
= ———— = 149 lb/hr
953
4) Calculate final air temperature (FAT).
Actual BTUH
FAT = EAT + ——————
CFM x 1.08
142,400
= 70 + —————— = 119°F
2640 x 1.08
5) Determine air mounting height at actual conditions.
At Table 4 conditions, mounting height of VS-137 is 23 feet
without diffuser and 36 feet with louver cone diffuser.
At actual conditions (10 PSIG and 70°F EAT).
Height = 23 x 0.98 (Table 6) = 22.5 feet (without diffuser)
= 36 x 0.98 (Table 6) = 35.3 feet (with louver cone
diffuser)
Louver cone diffuser shall be used.
NOTE: See ‘‘GENERAL SELECTION’’ for application details (page 3),
and Table 7 for noise level.
BTU CORRECTION FACTORS
TABLE 5
-10 0 10 20 30 40 50 60 70 80 90 100
0 970 1.54 1.45 1.37 1.27 1.19 1.11 1.03 0.96 0.88 0.81 0.74 0.67
2 966 1.59 1.50 1.41 1.32 1.24 1.16 1.08 1.00 0.93 0.85 0.78 0.71
5 961 1.64 1.55 1.46 1.37 1.29 1.21 1.13 1.05 0.97 0.90 0.83 0.76
10 953 1.73 1.64 1.55 1.46 1.38 1.29 1.21 1.13 1.06 0.98 0.91 0.84
15 945 1.80 1.71 1.61 1.53 1.44 1.34 1.28 1.19 1.12 1.04 0.97 0.90
20* 939 1.86 1.77 1.68 1.58 1.50 1.42 1.33 1.25 1.17 1.10 1.02 0.95
50* 911 2.13 2.04 1.94 1.85 1.76 1.67 1.58 1.50 1.42 1.34 1.26 1.19
75* 894 2.28 2.18 2.09 1.99 1.90 1.81 1.72 1.64 1.55 1.47 1.40 1.32
100* 880 2.41 2.31 2.20 2.11 2.02 1.93 1.84 1.75 1.66 1.58 1.50 1.42
-10 0 10 20 30 40 50 60 70 80 90 100
1.48 1.41 1.33 1.25 1.18 1.11 1.03 0.96 0.89 0.82 0.75 0.69
1.52 1.44 1.36 1.29 1.22 1.14 1.07 1.00 0.93 0.86 0.79 0.73
1.57 1.49 1.41 1.33 1.26 1.19 1.11 1.05 0.98 0.91 0.84 0.77
1.64 1.56 1.48 1.40 1.33 1.25 1.18 1.11 1.04 0.97 0.90 0.84
1.69 1.61 1.53 1.46 1.38 1.31 1.24 1.17 1.10 1.03 0.96 0.90
1.73 1.65 1.57 1.50 1.42 1.35 1.28 1.21 1.14 1.07 1.00 0.94
1.93 1.85 1.77 1.70 1.63 1.55 1.48 1.42 1.35 1.28 1.21 1.15
2.04 1.97 1.90 1.82 1.75 1.68 1.61 1.54 1.47 1.40 1.33 1.27
2.15 2.07 1.99 1.92 1.85 1.77 1.70 1.63 1.56 1.49 1.43 1.36
STEAM
PSIG
LATENT
HEAT
BTUH/lb
MODELS H & HS HORIZONTAL PROJECTION
ENTERING AIR TEMPERATURE °F
MODELS V & VS VERTICAL PROJECTION
ENTERING AIR TEMPERATURE °F
*
Special high pressure steam unit on request.
UNIT HEATERS