Pros and cons of clean room panel and flooring
Natarajan S Iyer
Clean room panels are extensively used for creating pharmaceutical manufacturing units because they are easy to erect as compared to civil construction, which was predominantly available 10-20 years ago and had a lot of limitations. Shrinkage cracks in most of the cases could not be avoided due to recurrence. Now we have clean room panels, which are preformed walls with an insulating material in between, which can be filled with polyuretherene foam (puff) or glass wool of various densities. Today, with advanced clean room technology, panels are made in a controlled environment. There is also much better control of heat transfer. All clean room panels consist of two thin sheets of metal, sandwiched at the end, insulated by glass wool. This metal sheet can be made of stainless steel, or can be a galvanised GI sheet, or in some cases, of non-metal. These panels are manufactured in fully automatic machines and the end points are riveted.
The ceiling of clean room panel has to be laid in a staggered manner as per the drawing, so that all the four corners do not come together, otherwise it becomes the weakest point for fluid/water seepage. When the panels are to be locked with each other, they should preferably have male and female interlocks, as the fixing is much better. These male and female interlocks have openings, which are provided for pipes or cables, should be sealed properly. The hangers thread type angles should be provided to support the clean room panels. The nuts should be adjusted to make all panels look like one plain sheet of metal. There should be two nuts to lock the system so that if any one walks on the panel, the nuts do not get loose, otherwise the entire alignment of panel can get disturbed. Out of the two nuts, one is generally made of castle, which contains a teflon seal or a nylon seal, which is self-locking. You should not run on the panels and all the suspenders should be rigid, having a low coefficient of expansion.
While making coving
Mostly, polyurethrene is used for flooring. The flooring is laid first, then the coving is done at the top, after which, the poly sheet is put at the top of the coving by welding it at the bottom, as shown in the diagram. Since there is no known method to find the integrity of welding in a polyurethrene flooring, there is a higher possibility of water leakage below the sheet, which may lead to uncontrollable damages.
The joints between the ceilings of control room panels with concrete structure should always be done as per the drawing. Whereever the panel goes into the wall, the cavity should be filled with ploysulphide sealant or other similar flexible material.
Whenever you suspend a laminar air flow filter, the suspenders LAFF should be designed in such a fashion that the gaps between the suspender and panel hole should be filled with puf (puf cans are available) so that there is no gap. When the entire ceiling is done, the most effective way of sealing the joints are, by applying epoxy coving material to close the gaps, by application of silicon. But since silicon is a softer material, it gets damaged when someone walks over it. Epoxy material is resistant and it seals the joints more strongly.
To find the integrity of welding of polyurethrene flooring an aluminium foil is stuck below the joints of PU flooring material or a copper tape is stuck on the floor and the joints are adjusted at the top of this tape, after welding is done. We can also use a spark tester after the welding, with 2 KV adjustment, and run over the entire welded area. If welding has a porosity or a gap, the spark will jump. This is a very important step to perform in and around the drain area to validate the welding of the polyflooring.
(The author is Chief Engineer at VHB Medisciences. He can be contacted at firstname.lastname@example.org)