Description of electron beam sterilization equipment
Writer: Sterilization Time: 2021-08-30 Browse: 970 ℃
The mode of action of E-beam irradiation, the penetrating ability of E-beam irradiation, the technological parameters of E-beam irradiation, the advantages and disadvantages of E-beam irradiation and its cost are discussed.
Mode of action
Ionizing radiation in the form of a beam of electrons
Medical device product requirements
Materials are compatible with radiation, penetrate boxes with bulk densities up to 0.25 g/cm3
compatibility Wide range of polymer
compatibility compared to gamma; some limitations due to oxidation effects
Largest processing unit:Boxes
Product exposed to an e-beam for a validated period of time to achieve a desired minimum dose
Control system can quickly stop and start the source manually or automatically
Tolerance for density variation:Low
Processing time for a typical 45-ft tractor trailer (~3,000 ft3):<8 hours typical for smaller
There is a need to simultaneously monitor a number of parameters to ensure that the prescribed dose is delivered (e.g. beam current, conveyor speed, product box size and weight)
Product release parameters
In order to release product to market, the following are required:
Control of the product manufacturing processes to ensure supply of material and product packaging is consistent with the validated radiation process
A validated processing configuration in which an array of dosimeters have been measured to demonstrate the relationship between processing parameters and minimum and maximum dose to product and a routine dosimeter measurement (validation requirements and methods are well described in ISO 11137-1)
A measurement of routine dose for a given processing run, which indicates that a dose within specification has been delivered. This measurement can be made as soon as the irradiation process is complete, so there is no required waiting time before release.
Pros (specific to medical devices suitability) E-beam
60-year proven track record
Equivalent to or less expensive than gamma for certain products
Product holdup (amount of product within the irradiator) may be smaller than in a comparable gamma plant
Quickest processing times
Cons (specific to medical devices suitability)
Not suitable for products that have challenging product geometries and localized regions of high-density materials
Inability to process in palletized format
Accelerator control cabinet
The control and safety protection system of the accelerator is composed of a programmable controller (PLC) and a master computer, which can control all kinds of logic program control of the accelerator, such as system preparation, electron beam irradiation, cessation of electron beam irradiation and shutdown.The system can monitor the accelerator and set the parameters, and has the function of safety interlock protection. When the abnormal situation occurs, the control system can automatically cut off the high voltage system of the accelerator and display the fault state.
Schematic diagram of control system
The control system consists of 1 main control computers and 4 PLC.The schematic diagram of the control system is shown in the figure above.The PLC used in the system is the S7 200smart series of SIMENS.PLC's CPU is connected through the MPI bus.PLC and distributed I/O are connected by PROFIBUS bus.Rs485/232 bus is used to connect PLC and terminals such as frequency converter, temperature controller and ion pump power supply.The main PLC and the monitoring computer are connected by Ethernet, and TCP/IP protocol is adopted to realize network control by remote monitoring and maintenance system on the Internet.The software is written by STEP 7 and C language. Some hardware functions are implemented by software, making the whole system easier to test, manufacture and maintain.
1.Realized the monitoring and control function of various input and output quantities, controlled the accelerator according to reliable control logic, and ensured the safe and stable operation of the accelerator.
2.Two control modes can be realized: manual control mode and computer control mode. Manual mode includes debug mode and normal operation mode.
3.In computer control mode, there are also operating mode (for upper computer), monitoring mode (for remote monitoring) and debugging mode (for installing and debugging subsystems).Under the mode of operation, can also according to the actual requirements change many parameters, mainly including: repetition frequency, the range of temperature and the temperature of the water cooling system, vacuum protection threshold, speed of conveyor , etc.
4.In the computer control mode, the control program and database are integrated. Importing historical data directly into the database for query, it is helpful for monitoring and maintenance.The written independent software can read the data, and reappear the running process of the accelerator through the data. It can not only specify the time period of replay, but also the speed of the replay can be adjusted.After adding the function of the database, the performance requirement of the upper computer is improved.
5. Remote monitoring is realized through network.Under the premise of authorization, remote monitoring, maintenance and operation can be realized through the network (the operation control function is cancelled due to safety).The implementation of the network includes LAN (TCP/IP protocol), fixed telephone network and mobile communication network.The host computer can be used as a server, and it can be accessed by a remote computer through TCP/IP access control system.You can access the control system anywhere on the Internet.（this system is optional）
Electrons, due to their charge and mass, have a much lower product-penetrating capability than either gamma or x-ray photons and can penetrate up to approximately 15 cm single- sided or 40 cm two-sided irradiation at densities up to 0.2 g/cc for electron energies up to 10 MeV
System repair downtime (e.g.source/system for machine sources; system for Cobalt-60)
Can vary from hours to days
Conveyor repair related items are generally quick
Accelerator-related issues can sometimes take days to repair
Reliability and maintenance
Stable and reliable in a daily production environment. Actual operational experience has demonstrated ~90% uptime
For low-density homogenous materials, e-beam is more efficient than gamma and x-ray for this subset of processing
The source of radiation can be turned off, which allows for easy access and repair
The source energy is electricity and does not require the material to be transported
Cons (equipment-related) E-beam
Additional complexity of equipment and process and validation when compared to gamma processing
Maintenance outsourcing or development of technical staff to manage and maintain equipment required
Need for ongoing replenishment of critical components over life of equipment
Costly parts due to complexity
Reliable and high electrical power consumption required
Cost of generator Includes accelerator, beamline, scan horn, installation, IQ and OQ. The cost of the accelerator strongly depends on beam power. Production throughput is proportional to beam power. It is possible to increase the e-beam source capacity at a later stage by adding power modules to the accelerator or by adding a second accelerator (if planned in the initial facility design).
Typically box conveyor sometimes with automated box flipping for dual side irradiation
The Safety Access System prevents unauthorized access into the accelerator room and irradiation chamber. Should there be an authorized intrusion in the irradiation area, the safety system instantaneously stops the accelerator irradiation.
Shielding is usually made of concrete. A typical foot print for an e-beam system including shielding and conveyor is about 20m x 15m.
fences, racks, furniture, forklifts
Building permits, fire department, environmental regulations such as noise
Costs that are proportional to production
Operators typically work in shifts. Processing boxes requires more labor compared with pallet processing.
Power Consumption Typical accelerators have power efficiencies from 20 to 50%. Accelerator power consumption stops when products are not processed. Other power consumption is for office and other non-accelerator related components. E- beam has considerably greater demand for electricity than gamma.
Spare parts stock may vary and can be expensive. The minimum spare parts to store are specialized consumables which require periodic replacements (e.g. cathode, tetrodes, klystrons, seals, filters, pipes). Other spare parts may be stored in order to reduce downtime in case of failure.
Spare parts required for the conveyor are similar compared with gamma.
Repairs / maintenance and ongoing Investment
Someone with specialized electronics and mechanics background needed for maintaining an accelerator.
Specialized expertise available from the manufacturer may be required due to equipment complexity.
This article describes the mode of action, penetration ability, process parameters, advantages and disadvantages and cost of E-beam.
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