Perfluoroelastomers on Demand - Made-to-measure Perlast® parts available in days. David Holt, Business Manager, Perlast®.

Perfluoroelastomers have changed the face of sealing in the chemical industry. But this is just the start. New high and low temperature perfluoroelastomers combined with rapid prototyping and design and manufacturing techniques are set to produce a quantum leap in plant productivity and maintenance cycles, believes Precision Polymer Engineering.

The chemical industry and its suppliers have been quick to take advantage of perfluoroelastomers' chemical resistance at high operating temperatures. Yet few have taken the next step to look beyond immediate sealing requirements and explore how perfluoroelastomers can increase plant productivity and extend production equipment and pump maintenance cycles even further.

Until now suppliers of perfluoroelastomers (FFPMs) have been renowned for their inflexibility and long lead times. Production lead times of 6 - 8 weeks are not uncommon. Such lead times are impractical when engineers are faced with a sealing problem; which is why Precision Polymer Engineering, manufacturer of the Perlast® range of perfluoroelastomer seals, has developed a design and manufacturing methodology that reduces lead times to days, if not hours, for standard O-ring FFPM.

In addition, it brings together a combination of short lead times and product flexibility that enables custom-parts tailored to individual requirements to be manufactured within days rather than weeks or months.

Integrated design and production

PPE specialises in rapid design and production of seals, often at short notice, from a range of over 350 elastomers. Its methodology is based on advanced CNC tool-making systems that reduce tooling manufacture to less than 48 hours. The facility to receive drawings in electronic format reduces lead times even further. Combined with a fast- track production facility, this gives the option of a guaranteed 3-day production service. By tightly integrating production with design, the company is enabling production of non-standard and complex parts in timescales normally only found with standard O-rings. This is due, in large part, to using 3D design technology to model and view parts prior to tooling manufacture increasing the first-time-success rate of complex parts.

Finite Element Analysis (FEA) is also used to help predict seal performance in situ, identifying and removing potential areas of weakness in component design well before tooling manufacture. This has helped to reduce sample lead times typically to under 5 days.

In view of the often critical applications where Perlast® is used in pharmaceutical manufacture for example, PPE maintains full development and production records of all seals in order to ensure repeat manufacture to the same high quality and to satisfy the requirements of statutory bodies in the food and pharmaceutical industries.

O-rings: O-rings are available in all standard European sizes as well as any custom size.

Integrated manufacture means there is no tooling charge for o-ring sizes below 250mm diameter, doubtless a pleasant surprise for companies used to paying for tooling for non standard size o-rings. This gives the customer complete freedom to choose the exact size of the o-ring instead of relying on standard sizes that could lead to a design compromise.

Perlast® can also be manufactured in any size up to 2 metre diameter. This is achieved without any joints in order to maximise performance.

Custom Parts: For many applications, performance can be increased by using custom mouldings for critical high volume parts for a diverse range of industries such as Paint Spray and Soap Dispensers.

By using advanced composite technology Perlast® can be bonded to lower-cost elastomers to reduce the amount of expensive perfluoroelastomer needed. Similarily, metal inserts can be used to improve mechanical performance. Composite technology is commonly used in large parts for the pharmaceutical industry where only a small area of the seal comes into contact with the aggressive solvent.

A limitation of this process is that the composite seal's maximum operating temperature is determined by the lower specification material. Special processes have been developed to maximise the bond strength between Perlast® and a wide range of materials such as PEEK, PTFE, stainless steel and aluminium as well as a selection of other elastomers.

Material Customisation Design customisation will take you so far and most applications can be made to work using standard perfluoroelastomer grades. However by selecting from a range of hardness between 50 and 90 shore, engineers are able to improve sealing performance even further.

There are a number other features that can be selected to improve the match of the elastomer to the application. In addition to black, a range of 5 colours can be used to help with identification ensuring the correct seal is used and aiding plant maintenance.

Also the ability to specify FDA approval or explosive decompression resistance allows selection of the optimum perfluoroelastomer grade, preserving the integrity of the application.

High Temperature Resistance. Perlast® perfluoroelastomer is the latest generation of perfluoroelastomers using an advanced patented cure system. This cure system improves on the cross-linked density of some traditional perfluoroelastomers increasing chemical resistance and high temperature stability.

Perlast® is available in grades that work up to 330 Deg C.

Applications: Cost of ownership (pumps and valves). Many applications that have traditionally used low cost elastomers such as EPDM or FKMs are now benefiting from specifying perfluoroelastomers. Significant savings can be made over the life-time of a pump or valve.

Reduced maintenance and service costs can far outweigh the initial cost of specifying a perfluoroelastomer whilst the benefit from increased customer satisfaction should not be underestimated.

Vacuum Discharge Valve The Pharmaceutical Industry has been steadily increasing the use of solvents for the cleansing of equipment between batches of chemicals.

For example, process changes at a chemical company using an EPDM expandable envelope seal on a ball valve caused increased down time due to unscheduled maintenance of the seals.

Operating under vacuum conditions in the range -15 to +260 oC, the envelope seal was inflated to seal against the ball under pressure and released by vacuum. But process changes introduced toluene. The EPDM seals quickly failed, causing product contamination and lost revenue. The solution was found by selecting a Perlast® Inflatable Envelope Seal, the vacuum discharge ball valve was restored to its original operational efficiency.

Moreover, the new seal material offered longer life and extended valve maintenance cycles. In addition, the seal was FDA approved which widely extended the range of chemical, food and pharmaceutical products that could be processed by the IBCs and mixing vessels.

Reduce Seals Stockholding

For one international chemical company producing of a range of chemicals and pharmaceutical products, using Perlast® perfluoroelastomer seals has allowed it to consolidate its seals stocks, reducing the number of seals. The physical properties of Perlast® are such that it acts as a "universal seal" giving greater operational latitude on the production plant.

Rapid manufacture of perfluoroelastomer seals is challenging the chemical industry to think in new ways about how it builds on the benefits of this elastomer technology. By reducing lead times from weeks to days, the chemical industry is able to explore sealing solutions that achieve greater plant productivity and reduced service and maintenance down-time.