Filters or strainers are commonly used to separate solids from fluid streams. The main outcome is to protect downstream equipment, but in some cases it also ensures satisfactory product quality. Which one you would use depends on the particle size distribution of your entrained solids. Mesh sizes can then be specified and you can survey suppliers to find the best solution.
Filters/strainers are generally installed in-line and require regular cleaning to ensure optimal function.
Process piping design is dictated by the code ASME B31.3. It is recommended that a qualified person is appointed for all piping design. Materials should be chosen to stand up to the fluid under operating conditions.
The two main types of piping are pipes and tubes. Both are defined in terms of diameter and wall thickness. Pipes are generally used for larger applications, and tubes for smaller applications. Tubes are able to handle higher pressures than pipes of the same wall thickness. Tubes are preferred in hygienic applications.
Pipe connections can be flanged, welded or threaded according to a user's needs. In some processes involving medical materiela only welds are acceptable.
Pipe diameters and distances directly influence the discharge pressure required from pumps.
Many medical waste treatment operations use batch processes. Small batch processes often employ a 1+1 arrangement (1 operating +1 standby) of pumps. Positive displacement pumps are common. Larger centrifugal pumps with variable speed can be more energy efficient but are usually not practical for small processes.
All parameters of a system can be monitored with either switches or transmitters. Switches give a digital output (binary) where transmitters provide an operating range.
Switches give feedback once a parameter satisfies their calibrated value. The configuration would be as simple as “parameter satisfied ? output = true” or “parameter not satisfied ? output = false”. This provides a binary indication of a specific process parameter at a specific point.
Transmitters provide continuous feedback on parameters throughout their effective ranges. Software can then be used to apply this information in control systems, e.g. A level transmitter for a tank could provide the operator with real-time feedback on tank levels by means of a HMI
High level control is commonly used to prevent overfilling of vessels and subsequent spillages. Low level control is commonly used to prevent pump damage. As mentioned, several pump types will suffer severe damage from even a small period of dry-running. It is common to interlock pump signals to switch off as soon as the low level on an upstream vessel is reached
Low level control is commonly used to prevent pump damage. As mentioned, several pump types will suffer severe damage from even a small period of dry-running. It is common to interlock pump signals to switch off as soon as the low level on an upstream vessel is reached.
Commonly used as part of a recipe management system to keep track of volumes. Flow switches are used to trigger alarms if flow states are not correct during specific windows, and can also be used to protect pumps.
Similar to flow control, critical when heating/cooling equipment requires control.
Commonly used as an alternative to flow/no-flow control. Can also be used to protect pumps and other equipment.
These instruments are used to detect positions of metal and non-metal parts alike. Commonly used to detect the positions of valve handles to ensure that all valves are in correct positions. Valve positions are commonly interlocked with pump status as closed valves in a transfer route are a health and safety hazard for most pump systems.
As with piping, instrumentation connections can be weld-on, flanged or threaded. Additionally some instruments require the installation of socket connectors. Of these, only weld-on is considered hygienic.
The most common control center for industrial applications is a PLC. This is an industrial computer with input channels used to interpret parameters and uses software to issue commands via outputs.
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