Biochemical Engineering Term Project
Spring 1997
Valves in Biochemical Engineering
Valves are an important part of the piping systems of biochemical processes.
There are many types of valves in industry. Some of the more popular ones are
listed here on the left. However, some of these valves are more widely used in
biochemical applications than others. Ball valves are popular, especially in
fermentation processes. Diaphragm valves are also used, but run the risk of
rupturing. Gate valves are never used, but are presented here for your
information. Any valve that has a stem which goes up and down
runs the risk of introducing outside organisms into the industrial process.
Because sterility is so important in the biochemical industry, companies must
pay close attention to the type of valves chosen for their processes. If a process becomes
infected, many companies will disassemble and sterilize all of the process
valves after the infected run. In other instances, companies will use a
continuous sterilizer for the substrate, which reduces the threat of a valve becoming a
sterility problem. Batch sterilization requires that all valves below the liquid level in the tank
be sterilized by steam passing through the valve into the substrate. By introducing steam into
the system, there is the possibility of foreign organisms entering. Also, proper control of the
valve is necessary, to ensure that an adequate amount of steam is introduced to maintain sterility.
Some frequently used valves in processes where sterility is important include
diaphragm, pinch, ball and plug valves. Diaphragm and ball valves are more
widely used in batch sterlization, but require considerable maintenance. Plug
type valves are more typically used for continuous sterilizing. In both the batch
and continuous cases, plug and diaphragm valves are commonly used for the inoculum
transfer and sterile feed piping.
Overall, process valves which maintain a barrier between the sterile process and the outside
environment are essential to biochemical processes.
These valves must be easy to sterilize, maintain and replace, and be devoid of pockets, so as not to
collect microorganisms over a period of time.
The pictures found in this project have been taken from the following
sources:
Perry's Chemical Engineer's Handbook
Albany Fitting and Valve Company Catalog
ITAPS.p.A Company Homepage
Galassi & Ortolani Valve Web Page
Portions of this term project were adapted from previous term projects by:
Kelly Gehrke, 1995
Tony Klinowski and Todd McCloy