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Lebowitz
U-bend transfer panels bring many make–break connections toacentral
piping termination point, providing amaximum flexibility for the production
function, yet assuring controlled sanitation through CIP cleaning and further
guarantee the integrity of all individual product and cleaning and/or sterilizing
flow path. Figures 1and 5illustrate the transfer panel concept. The use of manually
positioned transfer panel U-bends for establishing processing, CIP, and steamin-place
connections in ahighly automated system requires welding permanent
magnets that are encased in stainless steel rods to the center ofthe U-bend
connection. Proximity switches located behind the skin of the transfer panel detect
the presence or absence of aU-bend magnet between any selected pair of ports.
Whereas manual “make–break” or transfer panel connections may be
preferred or required between solution-containing piping and vessels and
product-containing piping and vessels, valves are more typically used to control
the flow within large-scale processing systems. Automatically controlled valves
afford software-based control ofboth the process and cleaning program toassure
proper cleaning of all vessels, equipment, and interconnecting piping. Common
valves used in CIPS and CIPR distribution systems are diaphragm valves (preferred
where positive barrier isolation is required), sanitary compression valves (as
commonly found in the food and dairy industries), and double-seat mix-proof
valves (used in CIPS and CIPR distribution to provide compact, conveniently
installed double block and bleed assurance).
Elimination of CIP Distribution Dead Legs
Acritical factor in any CIP distribution piping system is the elimination of dead-end
flow branches. While this discussion focuses on CIP distribution, the same
consideration is also due to many product piping applications, for both smallscale
areas, such as in transfer panels, and facility-wide distribution piping.
There are three methods of preventing dead-end flow branches in piping
systems. The first is by use of blocking valves at each flow branch. However, in
piping systems of any substantial magnitude, it is impractical to include blocking
valves at each point as needed along acomplex header. Itisespecially difficult to
design a“drainable” piping system using diaphragm valves, since in ahorizontal
run they must be inclined at an angle to meet this requirement and the actuators
occupy considerable space and require support. Flow control generally requires the
application of two valves, one in the run and other on the branch tee. Also, with
each added valve in the CIPS or CIPR distribution system comes extra hydraulic
static head loss, hardware/software controls, and maintenance requirements.
The second method, illustrated in Figure 6, permits the elimination of deadend
flow branches in CIPS and CIPR headers free of the additional blocking valves.
When CIPS is brought through the header to adistribution valve and then to atwoport
transfer panel (for isolation) before connection to the spray device, it fills the
header downstream of the branch, and this is normally adead leg. Now consider
what would happen in the CIPR header.Asflow discharges fromthe selected vessel
through the transfer panel to the CIPR header toward CIPR pump RP-1, flow will
back-up into the CIPR header dead-end toward MT-3. To eliminate this problem, a
CIPR flush valve is added from the far end of the CIPS header beyond MT-3 to the
far end of the CIPR header below MT-3. By pulsing the CIPR flush valve for brief
intervals during the CIP cycle, the CIPS and CIPR header can be subjected to brief
periods of flow,onacontinuous but intermittent basis throughout the full program.