Thomas Schulz reports on a new automatic system for sterile sampling of pure steam condensate.
In order to monitor the quality of pure steam in sterile plant in the pharmaceutical, food and beverage industries, samples are regularly drawn from the steam pipes and analysed in the laboratory for a possible contamination.
For this purpose, there are various systems, in which sampling is carried out manually or semi-automatically. The most important issues are that:
- The various systems do not really permit contamination-free sampling.
- The space requirement of conventional tubular coolers in order to condense the pure steam is relatively large due to their design.
- The design of some systems entails increased risk of scalding for the user.
- The plant operator or laboratory technician must normally supervise the entire sampling procedure in nearly all of the sampling systems currently available on the market. Understanding the above-mentioned problems, GEMÜ has developed an automatic system for sterile sampling of pure steam condensate.
System design
The complete automated pure steam sampling system consists of a multi-port valve with pneumatic actuators, a sampling bottle, a compact control unit, installed ready-to-connect on a mobile stand or as stationary version.
The multi-port valve is based on diaphragm valve technology, whose sealing system is certified by the EHEDG and is classified by the FDA as suitable for pharmaceutical production. An aseptic quick-action coupling connects the stainless steel or glass sampling bottle to this block.
A further small multi-port valve, the sampling unit, is positioned on the bottle; it controls sterilisation of the connection, condensate removal as well as hermetic sealing of the bottle after sampling. The valve actuators on this block are likewise controlled pneumatically.
The entire electrical control of the system is decentralised in a small electric control cabinet with integrated keyboard. This electrical control cabinet is installed directly next to the sampling multi-port valve, so that the operator has direct access to the overall system during production at any time. If required, the complete system can be installed on a mobile stand, so that it can be used flexibly at various sampling points in the production. The system requires a power supply of 230V 50/60Hz and a compressed air connection (max10bar). If required, the system can also be used for sampling of, for example, water for injection (WFI) or aqua purificata (AP).
During sampling and transport of the sample from the sampling point to the laboratory there is the danger of sample contamination in several process steps.
Conventional sampling systems have several weak spots depending on the procedure. These dangers are on the one hand due to the technology of the sampling components or systems and on the other hand due to operating personnel. The system should support the operating personnel during the critical phases or be designed in such a way that no operator errors can occur. Errors by operating personnel can never completely be excluded, however, if they should occur then they should have no negative effect on the sample.
Conventional sampling procedures can expose the sample to the atmosphere and/or even partly draw the sample in non-sterile 'grey' area, since the ambient air at the sampling point does not correspond to cleanroom requirements. The sampling bottles are normally autoclaved or pyrogenised, brought to the sampling point and then connected to the sampling point. For this purpose, the sampling bottle must be opened and connected to the sampling point. The GEMÜ system excludes this risk. The sampling block is firmly connected to the closed ring main. After autoclaving, the bottle is hermetically sealed against the environment by means of the multi-port valve and is transported and connected as such to the sampling point. The operator then starts the system; sterilisation is the first process step. This procedure sterilises the entire sampling block and the particularly critical area of the interface from the bottle to the sampling block. The bottle itself continues to be hermetically sealed; the developing condensate is drained to the outside via the sampling block. The bottle is only opened when the first sampling condensate is available for filling.
There is a further risk of contamination when the sampling bottle is disconnected from the steam pipe and during transport of the samples to the laboratory. Conventional procedures or systems used nowadays frequently only cover the opening of the sampling bottle with aluminium foil, which is neither sterile nor hermetically seals the sample. The risk of contamination increases with the transport distance. The sampling bottle used with the GEMÜ system is screwed onto a multi-port valve, the sampling unit. After drawing the sample, the system closes automatically and a slight overpressure is applied. The sample is hermetically separated from the ambient air and can therefore be safely transported over longer distances to the laboratory. The sample, which remains sealed leak-tight, is opened in the laboratory and can be analysed immediately and safely.
Conventional sample coolers with metre-long cooling pipes made of stainless steel or glass are very large in comparison to the GEMÜ sampling block with integrated cooling. Sampling systems which condensate the steam over water or other liquids must first be connected to these supply media. Leakages in these cooling systems lead to a contamination of the production rooms and cause substantial subsequent costs depending upon the classification of the room. An installation in a cleanroom is only possible with very high expenditure and costs depending on the specified cleanroom class. The GEMÜ multi-port valve is simply cooled by compressed air, which is available almost everywhere in the plant. Appropriate systems for the possible recirculation of compressed air are state of the art and inexpensive.
The operation of the system has been designed to be as simple as possible. The sampler must only attach the connection to the pure steam system by means of an aseptic quick-action coupling. Pressing a button on the control unit then starts the sampling process. Sterilisation and sampling then run fully automatically. Therefore, no contamination can occur from outside and the sample remains 'sterile'. The power supply (safety plug) and compressed air are also reconnected by means of quick-action couplings after changing the location, if the user decides for a mobile unit. In all other respects, the procedure is as described above. The sterilisation time as well as the condensate volume can be set individually from 50 to 1000ml by means of the operating keys. The danger of scalding of the service personnel is dramatically reduced, since the bottle does not have to be held during sampling at all.
Bottle handling is clearly easier and thus safer due to the hermetic separation of the sampling bottle from the ambient air before and after sampling. The operators can also save time, since they do not have to fear any contamination and the danger of scalding. No tools are required for the installation of the sampling bottle or handling of the system. Unskilled personnel can also use the system after setting.
The parameterised control process runs fully automatically after the programme has been started. The system is sterilised during the first programme step, the sampling unit keeps the autoclaved bottle closed. Then automatic sampling starts until the set condensate quantity has been achieved. The system shuts down automatically after the programme has finished. The benefit of this new system is a reduced sampling time with fully sealed flawless sampling considering the total expenditure for sampling of pure steam systems.
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Thomas Schulz is with GEMÜ, Ingelfingen-Criesbach, Germany. www.gemue.de