Many chemicals can react violently with general engineering materials, or quickly degrade and compromise them, with dangerous or catastrophic results. As a result, engineers frequently face the challenge of finding suitable fluid system components manufactured from non-reactive materials.
With tens of millions of unique chemicals known to exist already, and new ones being discovered or
synthesised every day, it may sound like an impossible task to choose the correct, unreactive, wetted material for any given chemical application. But fortunately, there’s one material which is so unreactive, it’s easier to list the handful of chemicals it does react with, than the tens of millions it doesn’t.
The substance is Polytetrafluoroethylene, or PTFE for short – the first of the fully fluorinated polymers, discovered by chance in 1938. Since then, research has added other related substances, including PFA
(Perfluoroalkoxy) and FEP (Fluorinated Ethylene Propylene).
What they all have in common are some remarkable properties, of which – for the chemical industry – the most useful is the fact that they are virtually inert to all known chemistries. This makes them an ideal material for fluid system components for use in the chemical industry.
From Ultra-Pure to Highly Toxic
Process chemistries are often required to be maintained at high purity levels, which can be very difficult to achieve with common engineering materials. At the opposite end of the spectrum, many chemicals are highly toxic even at concentrations of parts per billion. In these cases, a containment failure due to incorrect material or component choice could have very serious consequences.
So when designing a fluid system for chemicals, the choice of materials for the components is critical: not only to the process results but also – and more importantly – to the safety of operators and maintenance engineers.
However, choose components manufactured from PTFE, and you can relax. These can safely come into contact with chemistries ranging from ultra-pure water to highly toxic and corrosive compounds, with no unwanted effects. The fact that PTFE will not react means the components will compromise neither the safety and integrity of the system, nor the purity of the fluid they are carrying.
PTFE is also easy and economical to extrude or mould into tubing, fittings, valves, and other associated flow components. So you can assemble an entire chemical handling or delivery system from PTFE based components, all of which will remain totally inert and completely safe.
Choose Your Tube
The core of any chemical delivery system is the tubing that interconnects the various components.
Whilst PTFE tubing offers all the benefits of other PTFE components, other chemistries and applications may require other solutions. SMC, for example, manufactures tubing not only in PTFE but also FEP, PFA and SUPER PFA Fluoropolymers. As well as offering chemical resistance, this specialist tubing has an operating temperature range of up to 260°C, depending on the series. With tubing available in a range of imperial and metric sizes, with some available in translucent colours for easy identification, this is a highly versatile solution.
"It is essential for manufacturers of chemical systems to keep pace."
Form and Function
When you are designing a chemical fluid system, you will have a range of functional requirements to be fulfilled. You may require valves, regulators, pumps, flow meters, vacuum generators, and even thermal control units – all of which must offer the same low or non-existent level of reactivity. Fluoropolymer is a material which offers a workable solution for a wide range of these functional products.
When air-operated diaphragm pumps are present in a system, pressure regulation is often installed downstream, to define the system working pressure and smooth and reduce the pulse output of the diaphragm pump. There is also often a need to monitor the flow rate of chemicals through a system, which may range from as low as 1ml/min up to 45 L/min. Flow switches provide a solution and – when a non-invasive monitoring method is required – ultrasonic measurement versions are also available.
Maintaining the heat of a chemical can also be crucial, requiring an accurate and effective thermo controller. The HED thermo controller from SMC is one such device, allowing the temperature of a chemical to be directly controlled with an all-PFA heat exchanger and Peltier devices. Control is from 10-60°C, with an accuracy of +/-0.1°C.
Keeping Pace With Chemistry
With new chemicals being discovered or developed almost daily, and thousands of different applications within the chemical industry, it is essential for manufacturers of chemical systems to keep pace.
There are, for example, currently 12,000 basic SMC products, with over 700,000 variations. And new or improved products are added at a rate of 35-50 every year.
So when you’re putting together your next system, simply ask ERIKS for whatever SMC components you need, and you’ll get exactly the reaction you want.