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1、1976 CFR 212規(guī)范為6D，指主管道中心到支管閥門中心的距離應(yīng)小于支管直徑的6倍。 2、1993 美國(guó)高純水檢查指南為6D，指主管道中心到支管閥門密封點(diǎn)的長(zhǎng)度應(yīng)小于支管直徑的6倍。 3、2001 ISPE水和蒸汽基準(zhǔn)指南為3D，指主管外壁到支管閥門密封點(diǎn)的長(zhǎng)度應(yīng)小于支管直徑的3倍。 4、ASME BPE為2D，指主管內(nèi)壁到閥門密封點(diǎn)的長(zhǎng)度應(yīng)小于支管直徑的2倍。 5、WHO 建議為1.5D，應(yīng)避免大于分支管徑1.5倍的盲管。6、2010版中國(guó)GMP指南： 為了避免將來造成混亂,本指南建議死角長(zhǎng)度從管的外壁來考慮。我們建議避免對(duì)于最大可允許的死角做硬性規(guī)定。 我們應(yīng)該認(rèn)識(shí)到如果不經(jīng)常沖洗或消毒,任何系統(tǒng)都能會(huì)存在死角。 TheTruth about the 3D/6D Rule  The installation of pipework leads to recurrent discussions about how deadlegs can be prevented and about the maximum length outgoing pipes/pipe tees mayhave for the sensor. There is less throughflow in dead legs. Hence, it isharder to clean them and during thermal sanitisation it takes longer until these'branches' have also reached the required temperature. In calls fortender and tests the 3D/6D rule is often used for the specification, but notalways in the completely correct way. In order to further explain this, pleaseread following the history of this rule. The rule for the prevention of dead legs (in a WFI system) is mentionedfor the first time in the draft of the FDA Guides for Large VolumeParenterals (LVP), 21 CFR 212.49 in 1972. This requirement was taken up inthe FDA Guide to Inspections of high purity water systems in 1993 - onlynow it was called 6D rule. This document is still used by FDA inspectors asguidance for GMP inspections. In 2001 the dead leg rule reappeared in an ISPEguide. The ISPE Baseline Guide Water and Steam now talks about the 3Drule. Further statements can be found in WHO TRS 929 (1,5 D), WHO TRS 970 (3D)and in ASME BPE-2009 (2D). This is a standard of the American Society ofMechanical Engineers for BioProcessing Equipment. This means: 防止盲管的規(guī)則（在注射用水系統(tǒng)中）首次是1972年在美國(guó)FDA大容量注射劑（LVP）指南草案，21 CFR 212.49中提到的。這個(gè)要求在1993年被放進(jìn)了FDA高純水系統(tǒng)檢查指南中----現(xiàn)在我們叫它為6D規(guī)則。該文件到現(xiàn)在還被FDA檢查員用作 GMP檢查指南。在2001年，盲管規(guī)則在ISPE指南中出現(xiàn)。ISPE基準(zhǔn)指南“水和蒸汽”現(xiàn)在講的是3D規(guī)則。在WHO TRS929（1.5D）中、WHO TRS970(3D)和ASME BPE-2009(2D)有進(jìn)一步的說明。這是美國(guó)生物工藝設(shè)備機(jī)械工程協(xié)會(huì)的標(biāo)準(zhǔn)。它表示： But how does it work in practice? Is one rule more binding or better thanthe others? 但在實(shí)踐中要怎么應(yīng)用呢？是否有一個(gè)規(guī)則比其它的更具有法規(guī)效力呢？ One has to know that the 3D and the 6D rule cannot be compared directlybecause they have a different reference point. In the case of the 3D rule thelength L of the dead leg is measured from the pipe wall of the main pipe andput in relation to the diameter of the parting pipe. The initial 6D rulemeasures the length L beginning in the centre of the main pipe. 我們必須知道3D和6D規(guī)則并不能直接進(jìn)行比較，因?yàn)樗鼈冇胁煌臏y(cè)量點(diǎn)。采用3D規(guī)則時(shí)，死管的長(zhǎng)度是從主管的管壁開始測(cè)量的，與支管的直徑進(jìn)行比較；而6D規(guī)則是從主管的中心線開始測(cè)量的。 作為一個(gè)規(guī)則，“3D或更短”已經(jīng)證明了自己對(duì)水系統(tǒng)是有用的，并被認(rèn)為是理想的設(shè)計(jì)。但以下理論也是有效的：風(fēng)險(xiǎn)越高或產(chǎn)品附加值越高，設(shè)計(jì)死管更短。今天，1.5D在生物制品應(yīng)用中已是理想的設(shè)計(jì)。但這也表示一個(gè)舊的潔凈蒸汽系統(tǒng)的一支管道仍可以維持其6D長(zhǎng)度，而并沒有GMP風(fēng)險(xiǎn)。 零死角閥門 現(xiàn)在，零死角閥門（0D 閥門）已有生產(chǎn)，當(dāng)然成本會(huì)更高一些。各個(gè)廠商所設(shè)計(jì)的零死角閥門可能會(huì)有點(diǎn)不一樣。下圖是一種類型的零死角閥門，紅色線為主管流向，粉色線為支管流向，閥門密封點(diǎn)直接在主管管壁上(即L=0D)。
建議： 1、在使用點(diǎn)采用零死角閥門，減少使用點(diǎn)形成菌膜、污染的風(fēng)險(xiǎn)。 2、管道設(shè)計(jì)應(yīng)該基于風(fēng)險(xiǎn)的原則進(jìn)行評(píng)估采用哪種方式防止死角造成微生物污染的風(fēng)險(xiǎn)，如：在純蒸汽管道的非使用端，可能6D原則就足夠了。 3、如果是不可避免的情況下，實(shí)行特別的規(guī)定進(jìn)行說明來防止死角是非常重要的?？紤]的因素包括操作溫度、流速和使用頻率(如果死角是一個(gè)使用點(diǎn))。 4、應(yīng)該認(rèn)識(shí)到如果不經(jīng)常沖洗或消毒,任何系統(tǒng)都能會(huì)存在死角。 |
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