Fluoroplastic Containment TanksHolscot are World leaders in the development of FEP tanks and Diaphragms for Liquid Containment and Expulsion. Our exclusive processing experience facilitates innovative constructions in Fluoroplastics.
FEP Membranes and Diaphragms
In addition to unrivalled chemical resistance, FEP, PFA and ETFE improve on their parent material PTFE by being non porous. As such they represent an effective barrier to ingression by liquids into high risk areas. Nowhere is this more vital than in aircraft. Two areas in particular have benefitted from the use of fluoropolymers.
The use of Kevlar mesh around the fan casing of aircraft engines is widely acknowledged as an indispensable safety feature. However, Kevlar can be attacked by the more aggressive liquids which occur within these engines. It is vital therefore that the Kevlar is protected.
Holscot provides a heat shrinkable sleeve manufactured entirely from FEP, the most chemically inert thermoplastic. The protective sleeves are custom manufactured using film manufactured by Holscot. The thickness varies from 0.25 – 0.5mm and the sleeves are chemically etched on both sides to secure the sleeves to the casing and to facilitate later repairs if necessary. The sleeve itself can be manufactured to any diameter and width with whatever percentage shrink down is required. In addition, a pigment can be added for greater visibility. The shrink down can be achieved with any high powered hot air gun and a partial bond to the Kevlar is normal practice.
The sleeve is a proven protection barrier to all known Aviation Fluids and is capable of withstanding any normal maintenance knocks and bumps without compromising its efficiency.
A Repair regime using Self Adhesive Tape of FEP has been developed to allow on site repairs.
Toilets and Galleys
In the toilet and galley areas of aircraft, there will be inevitable spillages of liquids and it is imperative that these are contained within that area to prevent ingression into the avionics of the aircraft. FEP has been widely used to provide that barrier because of its non-porosity and non-flammability. Holscot has provided this in the form of simple sheets of material or as custom made membranes fabricated from sheet, vacuum formed welded and etched to exactly fit the contours of the area in question.
Focussing on Space transportation, traditionally elastomeric diaphragms have been used as a means by which to completely expel the propellant liquid from the tank. But, in recent years, the use of new propellant fluids, including green propellants, has forced tank providers to look elsewhere for a more compatible material and FEP has proven itself to be that. Inert to virtually all known chemicals and solvents, the use of FEP as a chemically resistant material has been recognised for many years. Indeed, it was considered and used in NASA experiments at the time of the first moon exploration missions.
Although, inevitably, FEP does not have the same elasticity as its predecessor, it has shown itself flexible and resilient enough to withstand cycling well beyond what is required of it in service. Holscot’s vacuum forming capability, combined with our skills in welding and even etching the material have been used to full effect on several projects with major Aerospace companies. In addition to being able to be used as a diaphragm, the FEP can also be used a liner for the complete tank. Holscot were called upon to provide both a liner and an expelling diaphragm for potable water tanks for the ATV missions to the International Space Station. More details can be seen at our Case Histories section.