A carbon fiber recycling company contacted AKO UK looking for advice on which type of valves to use within their unique application.
The process used within this company is typically explained as a high-tech papermaking, where they have a low concentration (~0.001%) carbon fiber suspension in water, but a key difference is they align fibers instead of random orientated mats. This means it is critical to prevent flocs and thus avoid any potential ‘catching’ points. For this reason, the company decided pinch valves would be very suitable for the application.
They were upscaling this process to a gravity fed system (2m head), with multiple high concentration feeder tanks feeding into a main tank. This requires open/closed valves, and potentially one valve that can be proportionally controlled. The company were planning on using 2″ piping throughout, ideally flanged to minimise any catching point from exposed threads. They were set on using flanged fittings as they have had bad experiences with threaded fittings in the past. Their system layout is detailed below:
valve for carbon fiber wet schematic diagram

Set up of Valve Products Confirmed

After some technical information and advice was discussed with this company, AKO offered some valve products from their range:
4x FTIV-A/B/C/D Feeder tank isolation valve
2″ bore, ON/OFF, pneumatic. VMC type Pinch Valve in stainless steel with flanged connections.
MIV Main isolation valve
2″ bore, ON/OFF, pneumatic. VMC type Pinch Valve in stainless steel with flanged connections.
PCV-1 Proportional control valve
2″ bore, but this is a throttling valve Proportional Control System to regulate the flow rate out of the main tank.

The set-up would be a normal pinch valve, linked with a Proportional Control System (PCS) to control the air pressure. If the water / line pressure is 1.2 bar (absolute), so 0.2bar gauge, the sleeve works as a spring so it would require a pilot/air pressure of 3.2 bar to fully close. Using the PCS on a 4…20 mA signal would mean they would set the 4 mA signal to 0 BAR and the 20 mA signal to 3.2 BAR. Then adjusting the PCS signal between 4 and 20 mA would give different closing points of the Pinch Valve.

AKO Valves require 2 BAR above the line pressure to close 100%, therefore if the line pressure fluctuates up and down throughout the process then the pressure would need to be adjusted when required.

Valve for Carbon Fiber Recycling Results

AKO UK supplied this company a 2″ flanged Pinch Valve (product code VMC50.03X.50F.50) from stock to be trialed.
After a short period trialing the Pinch Valve for carbon fiber recycling, one of the design engineers of the company told us that testing and seeing the valve in action was invaluable.

“We couldn’t test the full flow rate through it as we don’t have our full system up yet but we partial closing / opening worked well by varying the pressure (I thought it would be much more abrupt). That gives us confidence going forward with the pinch valves.”

VMC50.02x.50F.50
Pinch Valve used within this application – VMC50.03X.50F.50

VMC model, air operated, stainless steel body, Natural rubber sleeve, stainless steel PN10/16 flange connections.

The Project Coming Together

After discussing different options for valves during the R&D phase of the project and trialing Pinch Valves, the company had reached a stage where they were ready to source the parts they need for their big machine.

They decided to use AKO Pinch Valves from the VMC range with pressure switches (the same complete stainless flanged version that they trialed) for feeder tank output valves, and for the feeder tank output valves feedback system. The company will also be using the Proportional Control System fitted to a Pinch Valve to allow a percentage of air inside to partially close the sleeve.

valve for carbon fiber

Pinch Valve for Carbon Fiber Recycling Success

After another 12 months AKO UK got back in touch with the company building this machine, who told us that the valve for carbon fiber is working well for them. They were having some issues but these were to do with pneumatic controller for the valve, not the valve itself. They contacted the manufacturer of the pneumatic controller who supplied them with a full manual for the device, which allowed them to set the parameters they needed to get the system operating within their expectation. This resolved the issues.

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