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Seiberling
1. The sprays (Path 1) require 60 gpm (230 Lpm) at 25 psi (170 kPa) and are
supplied by asingle 1.5-in. (38 mm) line consisting of 15 ft of tube, 5elbows,
and 1diaphragm valve. Friction loss before the sprays at aflow of 60 gpm
would be 25.8 ft and for Path 1including the sprays would be 83.8 ft.
2. The inlet line (Path 2) includes 10 ft of 2-in. (50 mm) line, one 2-in. (50 mm)
U-Bend, five 2-in. (50 mm) elbows, and one 2-in. (50 mm) diaphragm valve.
Friction loss at aflow of 60 gpm (230 Lpm) would be 6.9 ft.
3. The transfer line (Path 3) includes 30 ft of 1.5-in. (38 mm) tube, 3elbows, and a
diaphragm valve to the TP and an additional 30 ft of tube, two 1.5-in. (38 mm)
U-Bends, five 1.5-in. (38 mm) elbows, and adiaphragm valve. Friction loss at a
flow of 60 gpm (230 Lpm) would approximate 47.8 ft.
When the valve controlling flow through Path 2isopened in parallel with
Path 1, the flow will split with approximately 46.5 gpm (184 Lpm) through the inlet
line and 5gpm (50 Lpm) through the spray,atahead loss through both paths equal
to about 4.2 psi (28 kPa), as determined by successive approximations. The inlet line
contains avolume of about 2.5 gal, and at 0.8 gpm, will flush completely in three
seconds. A pulse of five seconds duration once each minute, throughout the
program, will generally be sufficient to assure good results.
When the valve controlling flow through Path 3isopened in parallel with
Path 1, the flow will split with approximately 34.2 gpm through the transfer line
and 25.8 gpm through the spray, atahead loss through both paths equal to about
15.5 psi. The transfer line has avolume of about 4.6 gal and at 0.58 gpm, will flush
completely in 7.9 seconds, and apulse of 10 seconds duration once each minute will
generally be sufficient to assurecleaning the full length of line. Adevice sequencing
program would be required to supply Paths 1and 2for 5seconds, Paths 1and 3for
10 seconds, and then spray the vessel alone (Path 1) for 45 seconds. The transfer line
will remain full and though the inlet line will probably drain, the chemical cleaning
activity will continue through the period of no flow. Considerable experience has
demonstrated that valves should be controlled to assure flow through each path
three to four times during the pre-rinse, four to six times during the solution wash,
and four to six times during the combination of the post-rinse and acidified final
rinse. If apure water final rinse is used, the valves should be moved two to three
times for this step also.
The above calculations suggest that the results to be expected when placing a
long small diameter line or ashort larger diameter line in parallel with the spray
supply path, and the numbers for this example were chosen to be representative of
worst-case conditions in real-world applications. The friction loss estimates through
piping were calculated via aprogram by Domanico (8). The split flow approximation
was done by aprogram created and used by the author for many years.
Mixproof Valves and U-Bend Transfer Panel Combinations
The design mandate for alarge biotech R&D facility project was to provide for use
of six to eight vessels in each of several suites in combination with equipment in
four support rooms, for short- or long-term periods of use for product development.
The large U-Bend transfer panel shown in Figure 2enabled the configuration
of the entire process, following which all process and CIP operations were fully
automated. Asecond mandate was to permit any two larger tanks in any of five
suites to be used in similar combination with the larger tanks in other suites