With PTFE - which is easily the most chemically inert polymer - the issue is that of deformation. Hence, that any system that seeks to contain or transport fluids needs to ensure that all precautions are taken to accommodate the effects and minimise the risk of leakages. First, there exist a huge range of choices that can be compared with the chemical properties of the fluid in question to ensure that the polymer does not react during functioning. A major issue with using metals is that even though they may not necessarily corrode, there is no guarantee that there will not be some reaction with the chemical fluids. For the most part, OEMs will design their own systems and then look for polymer solutions that specifically match their application. Polymers also operate at a wide range of temperatures and given that they are not as hard as metals, they invariably bring sealing properties that metals cannot match. The softness of the material allows for the bellow to expand and contract, rather than succumb to higher pressures. At the same time, the wall thickness of a PTFE tube can be enhanced to allow it to accommodate high pressures. Such reactions can alter the properties of the fluids themselves, which would be a problem.

PTFE is an ideal medium, as there is no chance that the gas running through it will react with it and this ensures the purity of the system. 6. PTFE (Teflon) Tubes PTFE tubes are one of the most sought after for fluid transfer. Polymer bobbins are used a medium to shield the rubber from the metals. The combination of high temperature liquids and food grade requirements means that PEEK - which is FDA approved - is a key material of choice. PTFE tubes find application across industries such food processing, chemicals, electrical, and pneumatic lines, to name only a few.. ePTFE gaskets Expanded PTFE, like regular PTFE, comes with a stellar ability to resist chemicals. 3. Nonetheless, there are applications where nothing other than PTFE will suffice, and hence it is a preferred material in high-end chemical pumps. While PTFE can take high pressures - the combination of high pressure and temperatures can cause deformation in PTFE seals over time, leading to leakages. ePTFE arrests some of the issues seen with regular PTFE in that it is highly compressible (up to 65%) and offers an excellent sealing between harder surfaces including metals and glass. However, these materials still cannot accommodate the high temperatures that PTFE can.

In lower temperature applications (say, within 120°C), polymers such as POM (Delrin), PVC or even Polypropylene can be used. A combination of its ability to withstand high-temperature and high corrosion while offering high sealing makes it a material of choice. Polymer bobbins Some fluid sealing systems have a combination of metals and elastomers. The only drawback with regular  is that it lacks the elasticity, or seal-ability, of some softer materials such as silicone or Viton rubber. As always, it starts with the chemical compatibility and moves from there.The transfer of fluids can be a complicated affair. A key example of the application of  tubes is in analyser equipment.valves are used extensively in coffee machines is also very thermally stable, which means that the valve does not expand (and therefore tighten) even when higher temperature liquids are passed through it. Further, with stainless Pipe Fittings Manufacturers steel braiding, these pressures can be even higher. The key function of a bellow is to accommodate excess pressures and ensure that the system - typically a pumping system - does not fail over a long period of time. The choice of polymer here is entirely application based. This arrangement ensures that the bobbin, which can withstand higher temperatures and will not transfer heat, will keep the neoprene hose safe in the event that the clamp heats up. Polymer seals are a vast area of application and can include everything from: Ball valve seats Spring-energised seals Sealing rings Chevron V-packings Rotary seals Linear sealing strips There is no limit to the types of polymers that can be used in a sealing application.

This is primarily because even though PEEK is chemically very inert, it does suffer some reaction to the chemicals used specifically in pulp and paper manufacture. In most applications that involve fluid transfer, the system is simultaneously subject to one or all of the following conditions: Pressure Temperature Corrosion Each of these conditions further compounds the effects of the other. Paint mixing machines use PTFE valves to regulate the flow of liquid paint. Metal clamps - rather than being fitted directly on the rubber hose - will clamp around the bobbin which will then come in contact with the hose. The equipment is used to evaluate the chemical composition of gases that reach it though several tubes. However, a range of 1-2 million cycles is standard in the industry. For example, while a system may be equipped to handle high pressures, the added effect of corrosion can lead to ruptures or pinholes within the system that can cause failure. ptfe bellows The only issue with a PTFE bellow is that because  cannot be injection moulded, the bellow needs to be machined out of a block. PTFE is used primarily because it is soft and because it is chemically inert. Not only does the valve need to ensure that there is a tight sealing around it (fluids should not be able to flow around the valve), but the valve needs to resist the fluids flowing through it and ensure that thermal expansion due to high temperatures does not hinder the smooth movement of the valve. Polymer valves The function of a valve is to regulate the flow of fluids through a system. One application of PTFE valves is in the paints industry. This means that even more delicate assemblies can be fully sealed without having to put excess pressure on the bolted areas. The above are but a few examples of polymers and their applications in fluid sealing systems. For example, airline fluid systems use neoprene rubber for the transfer of fluids.