We produced FEP retractable coils for a water sterilisation application. As they were used with UVC lamps, the coils were made of FEP thin wall tube. The technical challenge we faced with this project was overcoming the susceptibility of the thin wall tube collapsing in order to prevent flow issues through the coil.

The project: Water sterilisation

We manufactured FEP extension coils custom designed to fit in our customer’s water sterilisation equipment. Used with UVC lamps to disinfect water within a water conservation system, the coils were thin walled to limit the loss of UVC transmission. We thermoformed several sizes of FEP tube into 1.5m long coils with an 100mm ID and an 120mm OD.

For this project, FEP was chosen as it is the best material for use with UVC. FEP is inert to ultraviolet rays and has a low absorption rate for UVC. FEP becomes only minimally degraded by the heat or UV rays emitted by the lamps. The fluoropolymer does not brittle or discolour when used with the strong light over time. In addition, very little UVC is absorbed by FEP and so the output of the lamp is not greatly affected.

The technical challenge: Preventing flow issues

The main challenge with this water sterilisation project was that the thin wall of the tube was prone to collapsing given the diameter of the coil was too small for the bend radius of tube. This caused a risk of flattening the inside surface of the wound coil, which would affect the flow rate and the volume of liquid running through the coil.

To remedy this technical issue, we developed a special thermoforming process as well as special tools. This ensured there was no deformation to the ID of the tube and prevented flow issues while accommodating the thin wall tube.

Our retractable coil services

Retractable coils are extremely adaptable, offering a smooth surface that germs cannot stick to and high working temperatures, and being chemically inert and acid and UV resistant.

All fluoroplastic tubing can be formed into extension coils using thermoforming technology. We can supply coils from our PTFE, FEP and PFA tubing in stock, as well as other fluropolymers. Custom sizes are also available; we can produce bespoke retractable coils in any shape or size. In addition, specialist fittings can be applied, such as flanged or flared ends.

Here at Adtech, we are specialists in delivering innovative fluoropolymer solutions for your technical applications. Find out more about our Retractable Coils.

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