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1-150.11
15
PERFORMANCE DATA
Steam Conversion Tables - Example Calculations
Conversion factor example #1:
For an HSB340S operating at 30 lb. steam and 50°F entering air temperature, determine the following:
• Capacity (Btu/hr)
•
Final air
temperature (°F)
• Condensate (lb./hr)
•
Maximum mounting
height
Solution:
The factors/data
necessary to solve this problem are as follows:
• Steam heating
capacity conversion factor for 30 lb. steam and 50°F entering air is 1.43, from Table 10.1.
• Air temperature
rise conversion factor is 1.40, from Table 11.1.
• The latent
heat of steam at 30 lb. is 928.5 Btu/lb., from Table 12.2.
• The mounting
height correction factor is 0.86, from Table 12.1.
• The standard
rated capacity of an HSB340 is 340,000 Btu/hr, from Table 13.1.
• The final
air temperature of an HSB340 at standard conditions is 120°F, from Table 13.1.
• The maximum
mounting height at standard conditions is 20 feet, from Table 13.1.
Btu
A
= Btu
S
x Heating Capacity Factor = 340,000 x 1.43 = 486,200 Btu/hr
ATR
A
= (FAT
S
- EAT
S
) x Air Temp Rise Factor = (120°F - 60°F) x 1.40 = 84°F
FAT
A
= EAT
A
+ ATR
A
= 50°F + 84°F = 134°F
Condensate rate = Btu
A
÷ Latent Heat of Steam = 486,200 ÷ 928.5 = 523.6 lb./hr
Max. Mounting Height
A
= Max. Mounting Height
S
x Correction Factor = 20 feet x 0.86 = 17.2 feet
Conversion factor example #2:
Which vertical unit heater model is required to deliver 155,500 Btu/hr at 20 lb. steam and 60°F entering air temperature. What will
be the actual capacity and rate of condensate production for the selected unit?
Solution:
The factors/data
necessary to solve this problem are as follows:
• Steam heating
capacity conversion factor for 20 lb. steam and 60°F entering air is 1.23, from Table 10.1.
• The latent
heat of steam at 20 lb. is 939.3 Btu/lb. from Table 12.2.
Btu
S
= Btu
A
÷ Heating Capacity Factor = 155,500 ÷ 1.23 = 126,423 Btu/hr (at standard conditions)
From Table 13.1, a V-139 model
meets the requirement with a rated capacity of 139,000 Btu/hr at standard conditions.
The capacity of the V-139 at actual conditions will be Btu
A
= Btu
S
x Heating Capacity Factor =
139,000 x 1.23 = 170,970 Btu/hr.
Condensate rate = Btu
A
÷ Latent Heat of Steam = 170,970 ÷ 939.3 = 182.0 lb./hr.
Alternate Solution:
Low Outlet Temperature models are normally recommended for steam pressures above 30 lb. However, the use of these
models with steam pressure less than 30 lb. is acceptable.
Based on the example above, a
V-161L model, from
Table 14.1, meets the requirement with a rated capacity of 127,000 Btu/hr
at standard conditions.
The capacity of the V-161L at actual conditions will be Btu
A
= Btu
S
x Heating Capacity Factor =
127,000 x 1.23 = 156,210 Btu/hr.
Condensate rate = Btu
A
÷ Latent Heat of Steam = 156,210 ÷ 939.3 = 166.3 lb./hr.