Cleaning and maintaining the chamber
When cleaning a sterilization chamber, it is important to follow the user manual and maintenance instructions provided by the manufacturer of the specific sterilizer. Cleaning agents and methods that are not explicitly recommended or approved by the sterilizer's manufacturer should not be used.
The reason for this is that, among other things, complex interactions which may damage the individual sterilizer, its fittings or its peripheral equipment, can occur during the surface-cleaning process.
3.2定期腔室维护（Regular chamber maintenance）
实际经验表明，在化学或电化学清洗的裸露金属内表面区域，通过用符合DIN EN 285（给水）规格的水每周擦拭冷室，能显著抑制甚至防止不良的表面变色/薄层，不用添加任何清洗剂。
Practical experience has shown that, on chemically or electrochemically cleaned bare metal interior surface regions of sterilizers, undesirable surface discolourations/films can be significantly inhibited, or even prevented, by wiping out a cold chamber on a weekly bases with water that meets the specifications of DIN EN 285 (feed water), without adding any cleaning agents.
Any residues stubbornly adhering to the interior surface of the chamber (e.g. from labels, etc.) must be manually removed as soon as possible with the use of appropriate scraping tools (plastic scraper or other similar items, do not use metal tools). However, when doing so, one must take care not to damage (scratching or other forms of da- mage) the chamber's interior surface.
The use of chemical substances to remove residues on the interior surface of the cham- ber should first be approved by the chamber's manufacturer.
Once any films that can easily be wiped away are removed from the chamber's interior surfaces, the stainless steel surface can also be selectively repassivated as part of regular chamber maintenance. This can be carried out in an accurate and reliable man- ner with the use of wet-chemical acidic passivation solutions. Depending on the specific manufacturer, different aqueous solutions offer the optimal combination of surface care and repassivation capacity.
Removing rouging films or corrosion products
Among the specialists directly impacted by this phenomenon (equipment manufacturers and users), there is presently a wide range of different opinions on the cause, resulting problems and recurring need for restoration related to films in sterilization chambers.
A number of those involved describe these films mainly as 'merely visually bothersome', whilst others demand a periodic residue-free removal. The marked difference in attitude towards these issues makes it clear just how controversial the phenomenon is among experts today.
For the purposes of practical application, this means that, with the aid of a risk analysis, every responsible central sterile services department (MPPU/CSSD) must ultimately decide on its own shortand medium-term policy for its immediate sphere of influence.
If a department decides to implement periodic mechanical, chemical or electrochemical restorative measures, it has an array of different options to choose from – all of which, however, must be performed by specialist companies in cooperation with both the equipment manufacturer and the user.
All measures require the following:
➡ The operator, sterilizer manufacturer and rehabilitation company specialising in sensitive stainless steel surfaces must all work together
➡ Fittings must be removed and treated separately
➡ Occupational-safety measures must be planned and adhered to
➡ Operator must account for sterilizer downtime
➡ Where applicable, dust protection walls must be put up and certain operator-specific safety precautions taken
➡ Quality control, including documentation of rehabilitation measures, must be carried out
Figures 10 and 11 in this brochure are intended to illustrate the necessary work involved in the on-site removal of surface films in sterilization chambers.
In general, different options or combinations of techniques are available for effectively removing surface films. These options should always be decided on in consultation with all of parties involved. These decisions should take into account both the severity of the rouging film and, above all, the local conditions.
图10：创建工作区域（防尘墙）Creating a work area (dust protection wall)
Quality assurance (surface roughness measurement on the chamber's interior surface)
If a chamber's interior surface has been severely discoloured by rouging, the affected regions can be cleaned-up for a more sightly appearance by performing a thorough mechanical cleaning (using abrasive mechanical processes).
It should be kept in mind that, during this technical procedure, a significant portion of the iron-oxide-rich particles will inevitably be compacted into the stainless steel surface and thus stored there, which means that corrosion is bound to form again in the near future as the apparatus continues to be used. In most cases, the rouging/corrosion film thus reappears before long.
For this reason, a purely mechanical surface rehabilitation should be viewed in an critical light.
In some cases, stubborn soiling also occurs, e.g. from adhesive labels which can be well and truly baked onto the surface at the temperatures used in sterilization. Aside from soaking the affected area in water or chemical solvents and then using plastic spatulas for removal, there is no other alternative to a mechanical cleaning in these situations. When soiling of this type occurs, mechanical cleaning is also necessary as a pre-treatment for other chemical or electrolytic treatment options that may be used.
与符合DIN EN 285（给水）规格的（非常简单）定期护理/清洁的主要区别在于使用合适的不锈钢清洁剂（不含氯化物！）并且用更粗糙的纤维羊毛来代替棉布。也可以通过机器（例如刷砂或抛光机）进行清洁。为此，（砂光/抛光）布或皮带应适合机器，以便于机械去除薄层。 但是，这并不能最大限度地减少适用于机械清洁方法的基本技术注意事项。
The main difference to (very simple) regular care/cleaning with water that meets the specifications of DIN EN 285 (feed water) is that suitable stainless steel cleaners (containing no chloride!) are used, and that rougher fiber fleeces are used in place of cotton cloths. Cleaning can also be performed by machines (e.g. brush-sanding or polishing machines). To do so, (sanding/polishing) cloths or belts are fit onto the machines to facilitate the mechanical removal of the films. However, this does not minimise the basic technical caveats that apply to mechanical cleaning methods.
图12a:机械恢复措施（Mechanical rehabilitation measures）
图12b:机械恢复措施（Mechanical rehabilitation measures）
Particularly where surfaces are to be mechanically sanded/polished or electropolished, the procedure used to perform mechanical rehabilitation must be carefully considered or adapted, as the condition of the surface (e.g. surface roughness) can be deteriorated as a result. When the interior surfaces of a chamber are electropolished, mechanical processes—including the use of fibre fleece materials or even brush-sanding/polishing measures—have an adverse effect, at least locally, on the stainless steel surfaces.
A thorough cleaning will usually destroy the passive layer. Waiting for a certain amount of time (normally about 48 hours) whilst also allowing air to freely enter the chamber is therefore recommended before putting the system back into operation, so as to allow the passive layer to regenerate (natural repassivation). Active (wet-chemical) passivating agents can also be used to optimise and greatly speed up the repassivation process. This approach also improves the passive layer's chemical characteristics (e.g. thickness, Cr/Fe ratio).
However, it is important to keep in mind that this mechanical grinding of stainless steel surfaces causes a permanent destruction of the passive layer. Experience has shown that this then eliminates the possibility of a complete natural self-regeneration of the passive layer, or even a regeneration that is equivalent to the results seen on electropolished surfaces. This means that a natural air-based repassivation will take place either to a limited extent or not at all, since stainless steel surfaces that have been structurally altered (damaged) by mechanical processes no longer possess their full passivation capacity. In these situations, however, wet-chemical repassivation agents can be used to at least promote a repassivation.
Once the mechanical cleaning is complete, it is important to ensure that all residues (e.g. dust and any sanding/polishing materials) are completely removed.