Optical Fibre Production — Gas & Pressure Control (UK)
From MCVD/OVD/VAD preform deposition and helium‑assisted fibre drawing to UV coating and ribbonising, optical fibre lines demand precise, fast and repeatable control of gases, pressure and liquids. Any drift in oxygen, chlorine, helium or dopant flows, or instability in chamber/back‑pressure, can introduce refractive‑index errors, micro‑bends, coating defects and yield loss.
Premier Control Technologies supplies and supports Alicat Scientific mass‑flow and pressure controllers, together with Equilibar back pressure regulators and Drastar high‑purity pressure regulators, across the UK.
Preform manufacturing (MCVD / OVD / VAD)
Typical challenges
- Ultra stable low flow dosing of oxygen, chlorine and dopant gases for soot deposition and sintering
- Fast step changes / pulsing during gas switching without overshoot or long settling
- Purity and pressure stability from gas cabinets to tool inlets
Why Alicat here
- Sub sccm to slpm accuracy & speed: Alicat's laminar differential pressure architecture with integrated P&T compensation gives fast response and broad turndown, ideal for MCVD recipe steps and dopant transitions.
- Multi gas, multi range flexibility: Switch gases (O₂, Cl₂, He, Ar, specialty dopants) and ranges on instrument to accelerate R&D and changeovers. COMPOSER™ supports user gas mixes without factory recalibration.
- Pressure control: Alicat PC/PCS units stabilise line or chamber pressure to decouple flow pressure interactions during burner ramp/soak.
Support components
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- Equilibar back pressure regulators (BPRs): frictionless multi orifice design maintains stable exhaust back pressure even at ultra low flows and with condensable by products—improving deposition uniformity.
Fibre drawing (draw tower, He cooling, primary/secondary coat)
Typical challenges
- Helium consumption & stability: keeping He flow steady through transients to control cooling rate and micro bend risk
- Draw tension pressure effects: fast, stable pressure response around the furnace and capstan zones
- Resin coating quality sensitive to back pressure and viscosity changes
Why Alicat here
- Low ΔP, vacuum friendly variants support accurate flow where upstream pressure is limited; fast control reduces overshoot during tension/speed changes.
- Integrated data & totalisation (analog + Modbus/serial) provide high rate data for statistical process control and helium usage optimisation.
- Direct pressure control with Alicat PCs keeps draft/line pressure stable through pump downs or valve movements, reducing draw instability
Support components
- Equilibar BPRs on coating/exhaust loops damp pressure spikes and hold setpoint with mixed phase or changing viscosity, improving concentricity and cure uniformity. High temperature options up to ~450°C are available where needed.
- Drastar line regulators upstream of MFCs stabilise inlet pressure to the tower’s He and N₂ lines, improving MFC accuracy and reducing settling time.
Ribbon forming (stack, matrix, UV cure)
Typical challenges
- Consistent inerting and purge: for matrix application & UV cure
- Pressure stability : in low flow manifolds feeding multiple fibres
- Recipe agility for development lines
Why Alicat here
- Fast, repeatable control at sub sccm flows keeps purge levels and O₂ ppm stable in enclosures.
- Multi gas libraries and on device range changes accelerate trials (e.g., switching N₂/Ar or tweaking purge rates).
- Compact systems / gas mixing: your gas mix skids built with Alicat MFCs simplify commissioning and provide plug and play recipe control for multi fibre ribbon lines.
Support components
Why Alicat is a strong fit for optical fibre producers
- Speed & stability at ultra low flow: Millisecond class control dynamics with pressure & temperature compensation maintain precise mass flow in sensitive deposition and purge steps.
- Broad turndown & multi gas capability: One instrument covers R&D and production ranges, reducing spares and downtime; COMPOSER™ supports custom gas mixes.
- Connectivity for process intelligence: Analog (0–5V, 4–20mA) and digital (Modbus/RS 232, etc.) plus onboard totalisers simplify DAQ/PLC integration and traceability.
- Clean construction options: 316L SS and metal seal variants align with high purity requirements common on preform and draw tools.
Equilibar & Drastar for fibre
- Equilibar BPRs — frictionless, multi orifice diaphragm regulators offering exceptional resolution from ultra low to high flows, compatible with mixed phases and condensable; ideal for MCVD exhaust, coating back pressure and pilot controlled precision loops (with an Alicat PC as the electronic pilot). High temperature variants available.
- Drastar high purity regulators — electropolished 316L, tied metal diaphragms, UHP VCR®/face seal options and low droop for gas cabinets, cylinders and point of use regulation (O₂, He, Cl₂, dopants). They provide stable, clean supply pressure into Alicat MFCs, improving accuracy and shortening settling times.
Common Customer Questions
By combining a fast control valve with laminar differential pressure sensing and real time P&T compensation, Alicat maintains accurate mass flow through back pressure and temperature changes typical of burner steps or gas switching.
Use a BPR wherever back pressure stability drives quality—e.g., MCVD exhaust or liquid coating loops. The multi orifice diaphragm design handles very low flows and mixed phases without the hysteresis seen in spring type regulators.
Drastar's UHP materials, electropolish and metal diaphragms keep gas streams clean while delivering low droop, stable outlet pressure into MFCs—essential for flow accuracy during long draws.
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