EN 285专题答疑: EN 285在大型灭菌区性能检测及蒸汽质量检测中的应用

EN 285专题答疑: EN 285在大型灭菌区性能检测及蒸汽质量检测中的应用

自从上次Keith Shuttleworth先生做客天津盛源科技有限公司为大家深入讲解EN285标准,我们收到很多学员提出的问题,在此为大家整理出几个具有代表性的问题进行展示:

01

Question:

Is there a certain order to be followed when we perform a steam quality test?

问:

蒸汽质量检测3个参数执行的顺序?

Answer:

The order in EN 285 is 1.Non-condensable gases, 2.Dryness and 3.Superheat test. There is no engineering or logical reason why this order is required, though we tend to follow this order when we carry out and report tests. Because of the way the test points on the test elbow are used we often carry out the non-condensable gas test and the dryness test at the same time.

答:

EN 285中的顺序为1.不凝性气体,2.干燥和3.过热测试。尽管需要在执行和报告测试时遵循该顺序,但没有工程或逻辑上的理由要求执行此顺序。由于使用测试弯头上的测试点的位置关系,我们经常同时进行不凝性气体测试和干燥度测试。


02

Question:

How do we solve the poor repeatability when perform a dryness test?

问:

如何解决干度值测试中重现性差的问题?

Answer:

For the results to be repeatable, the test method should also be repeatable. Simply following EN 285 will not allow this! Because the calculation we use does not take account of heat losses to the environment, the longer the test proceeds, the worse the result tends to be. To carry out the test repeatably, the amount of water used to fill the flask should be as close to being identical between tests and the temperature of the water used should also be close from test to test. Provided that this is the case and the end temperature for the ending the test is the same (before agitation of the flask). Another factor is that the insertion depth of the temperature sensor into the flask should also be the same between tests.

答:

想要获得具有重现性的测试结果,要求测试方法保持重现性。单纯地遵循EN285要求的检测方法无法做到这一点。因为我们使用的计算没有考虑环境的热损失,所以测试进行的时间越长,结果就越糟。为了重复进行测试,在两次测试之间填充烧瓶的水量应尽可能接近相同,并且每次测试所用的水温也应接近。在这种情况下,并且结束测试的最终温度是相同的(在搅拌烧瓶之前)。另一个因素是温度传感器在烧瓶中的插入深度在两次测试之间也应相同。

EN 285 specifies that the flask fill volume should be 650ml +/-50ml. We would suggest 650ml +/-20ml. EN 285 specifies the water temperature should be between 0 and 27℃. We believe that the water temperature should be close to ambient the starting temperature +/-2℃ between tests. We always remove steam from the flask the very first reading we get that indicates that the water is 80℃. We then agitate the flask to get a homogeneous temperature reading.

EN 285规定烧瓶中水的填充量应为650ml +/-50ml。但是再实际操作中我更建议将这个范围所缩小到650ml +/-20ml。EN 285规定水温应在0到27℃之间。我认为测试之间的初始水温应接近环境温度,偏差在+/-2℃之内。我们始终会在获得第一个读数时即从烧瓶中除去蒸汽,这表明水为80℃。然后,我们搅拌烧瓶以获得均匀的温度读数。

If you consider the extreme cases which are in accordance with EN 285, one could be that the flask is filled to 700ml with ice cold water. The other is that the flask is filled to 600ml with water at 27℃. To heat the different amounts of water from different starting temperatures means that the tow tests will take different times and you will get different results because of the unmeasured heat losses to the environment

如果考虑符合EN 285的极端情况,则可能是用冰冷的水将烧瓶装满700ml。另一个是将烧瓶在27℃的水中加满600ml。从不同的起始温度加热不同量的水意味测试将花费不同的时间,并且由于对环境的不可估量的热量损失,用户将获得不同的结果。


03

Question:

Where should the samples be taken from for the tests?

问:

应该从哪里获取样品进行测试?

Answer:

The tests are of the steam supply to the sterilizer and not of the steam within the sterilizer. The samples should be taken on the individual supply pipes to each sterilizer between the steam distribution system and the steam on/off valve for the sterilizers. Also, the tests should be carried out on every sterilizer and not groups of sterilizers from a single test point.

答:

测试是针对供应到灭菌器的蒸汽,而不是灭菌器内的蒸汽。样品应在蒸汽分配系统和灭菌器的蒸汽开/关阀之间的各个灭菌器的单独供应管道上采集。另外,应在每个灭菌器上进行测试,而不应从单个测试点对灭菌器组进行测试。

A sample point is required which has be installed into the steam pipework if test points for the tests are not included within the sterilizer pipework design. We call this a steam quality test elbow and it should be the same size as the pipe supplying the sterilizer with steam.

如果在灭菌器管道系统设计中未包含测试点,则需要将其安装到蒸汽管道中。我们称其为蒸汽质量测试弯头,其尺寸应与向消毒器供应蒸汽的管道的尺寸相同。

The sample for non-condensable gases is taken from the top of a horizontal pipe, the sample for the dryness and superheat tests is taken from a pitot tube which is inserted into the flow of steam and a steam temperature sensor is installed. The location of this is less important than the other two which are really mandatory.

不可冷凝气体的样品取自水平管的顶部,干燥和过热测试的样品取自皮托管,该皮托管插入蒸汽流中,并安装了蒸汽温度传感器。它的位置不如其他两个重要,其他两个是强制的。


04

Question:

When in the process cycle should the sample be taken?

问:

灭菌循环中应该何时取样?

Answer:

The steam quality tests are started when steam enters the sterilizer chamber for the first time. The description is exact and does not mean when the sterilizer enters the heating phase or when the sterilization stage commences, but when steam enters the chamber for the very first time. This is usually on completion of the first vacuum pulse during air removal. This is deemed to be the worst case condition, because the chamber is at its coolest and is likely to result in the greatest steam demand.

答:

当蒸汽首次进入灭菌室时,将开始蒸汽质量测试。该描述是准确的,并不意味着灭菌器何时进入加热阶段或何时开始灭菌阶段,而是蒸汽首次进入腔室时的描述。这通常是在排气期间完成第一个真空脉冲时完成的。这被认为是最坏的情况,因为腔室处于最冷的状态,并可能导致最大的蒸汽需求。

The end point of each test is provided in the test methods and are not expected to occur in the first steam pulse and will include periods where the sterilizer is pulling a vacuum. This can be anticipated and does not represent a problem. When the test is completed, the cycle can be aborted ready for the next test.

在测试方法中提供了每个测试的终点,并且预计不会在第一个蒸汽脉冲中发生,并且将包括灭菌器抽真空的时间段。这是可以预期的,并不代表问题。测试完成后,可以中止循环,以准备进行下一个测试。

Because logically, there is only one point in a cycle where steam enters for the first time, if you wish to run three dryness or non-condensable gas tests, you need to start three cycles for each of the two tests.

从逻辑上讲,在一个循环中只有一个点是第一次进入蒸汽,因此,如果您要进行三个干燥或不可凝性气体测试,则需要为两个测试中的每个启动三个循环。

This picture which is a pressure trace of a sterilization process, shows where steam enters the chamber for the first time. To be aware of this, someone needs to be watching the chamber pressure display, though with experience, you will probably be able to hear steam entering the chamber.

该图片显示的是灭菌器灭菌过程的压力曲线,显示了蒸汽首次进入腔室的位置。要知道这一点,有人需要观察箱内压力显示,尽管有经验,您可能会听到蒸汽进入箱内。


05

Question:

Is it normal when I get negative figure from superheat test?

问:

过热值为负数正常吗?

Answer:

The acceptance criteria for the superheat test is that the temperature measured in the expansion tube is less than 25°C above the boiling point at the local environmental pressure – 100°C at sea level.

答:

过热测试的可接受标准是,膨胀管中测得的温度在当地环境压力下比沸点海平面温度100度,高出25°C以下。

This test always seems to pass these criteria without any problem. What concerns many however is that the results obtained are often below 100°C which is counter intuitive, if you are aware of the theory of the test.

该测试似乎总是通过这些标准而没有任何问题。但是,让许多人担心的是,如果您了解测试的原理,那么获得的结果通常会低于100°C,这是非常直观的。

The answer to this lies in the test design, which assumes theory and practice will coincide exactly. When steam flows from an orifice, it results in a low pressure area close to it. This results in steam which has condensed on the wall of the expansion tube to be sucked towards the orifice and where it gets entrained into the steam flow. This results in the low temperatures experienced and is a function of the test method and not the person conducting the test. For this reason, there is little point in conducting three superheat tests as they always pass.

答案在于测试设计,它假设理论和实践将完全一致。当蒸汽从孔口流出时,会在其附近形成低压区。这导致冷凝在膨胀管壁上的蒸汽被吸向孔口,并被夹带到蒸汽流中。这会导致测试温度降低,这是测试方法导致的,而不是测试人员。因此,进行三个过热测试总是可以通过的。


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