Brochure

116
Selection Guides
Hoffman Specialty
®
Selection Guidelines
Conditions:
In this example, a pressure/temperature regulator has to
be selected to regulate the steam going into a steam to
water heat exchanger. Due to a planned plant addition in
the next 5 years, the steam system will be enlarged.
Problem:
The exchanger heats water from 50°F to 150°F (10-65°C)
and has an assumed water flow of 50 gpm (189 lpm).
The heat exchanger is limited to a 20 psi (1.4 bar) steam
pressure. Assume the steam supply pressure is 100 psi
(6.9 bar).
Known Data:
Temperature Rise — 150°F - 50°F = 100°F (66 - 10 = 56°C)
Water Flow — 50 gpm (189 lpm) = 3000 gph (11,356 lph)
Steam Inlet — 100 psi (6.9 bar)
Steam Outlet — 20 psi (1.4 bar) (heat exchanger limit)
Procedure:
1. Refer to page 104 to obtain the steam required
to satisfy the above conditions. This would be 2500
lbs./hr. (1134 kg/hr.) according to the tables.
2. Since it is planned to enlarge this system at a later
date, refer to the steam capacity tables for a normal
port to obtain the regulator size .
Example 2.
Conditions:
In this example, the steam supply to the process equipment in
the installation (system) will be regulated by one Series 2000
pressure regulator. Assume all equipment will be operating at
the same time at a constant load.
Problem:
Calculate the steam load requirements for all of the equipment
in the process system by referring to the equipment name
plate. Then select a Series 2000 pressure regulator from the
Steam Capacity Tables to determine the specific model
pressure regulator and valve size needed.
Procedure (continued):
4. Be sure to review the recommendations for good
practice in selecting pressure regulators.
5. Refer to the Full Port Capacity Table page 45 first for
the selection. The normal and reduced trim capacity
tables should be used if there is a possibility the
system will be expanded in the future.
6. Select the smallest regulator possible that will handle
the steam load requirements. Typically it can be found
in the Full Port Capacity Table.
7. When the outlet steam pressure is 50% or less of the
inlet pressure, use the lowest outlet pressure shown in
the capacity table.
Answer:
1. Referring to the Full Port Capacity Table, with the
conditions given above under procedure, the correct
valve to select would be a Model 2100 1
1
⁄
2
" Main
Valve-Full Port.
2. Since in this example there is no supply of
compressed air in the plant nor a need to also control
temperature, a spring pilot would be selected to
handle the outlet pressure requirements. This would
be a Model SPS-30 with an adjustable range of 2 to 30
psi (.14 to 2.0 bar). Adjust the pilot to 20 psi (1.4 bar).
A model SPS-60 pilot with an adjustable range of 5 to
60 psi (0.3 to 4.1 bar) could also be used.
Procedure:
For this problem assume :
1. An inlet pressure of 75 psi (5.2 bar).
2. An outlet pressure of 20 psi (1.4 bar).
3. The steam load adds up to 3200 lbs./hr. (1453 kg/hr.)
as shown to the left.
Known Data
Inlet pressure 75 psi (5.3 bar)
Example 1.
Sizing Examples
Series 2000
Equipment
Operating Maximum Steam Loads Pipe
Equipment Pressure Pressure Requirements Size
Identification psi (bar) psi (bar) lbs./hr. (kg/hr.) in.
A 20 (1.4) 40 (2.8) 300 (136)
1
⁄2
B 20 (1.4) 30 (2.1) 600 (272)
3
⁄4
C 20 (1.4) 25 (1.75) 400 (181)
3
⁄4
D 20 (1.4) 25 (1.75) 800 (363) 1
E 20 (1.4) 25 (1.75) 500 (227)
1
⁄2
F 20 (1.4) 50 (2.5) 600 (272)
3
⁄4
Total Capacity 3200 lbs./hr. (1453 kg/hr.)
Pressure and/or Temperature Pilot Operated Steam Regulators (continued)