Sourcing mass-flow controllers from China

Duty and classification for flow controllers

Heading 9032 covers automatic regulating or controlling instruments and apparatus. For a mass-flow controller, describe the sensor, feedback loop and regulating valve together. Specify whether you import a complete controller, a digital valve controller, a listed gas panel or a replacement part. See the wider automatic pressure controller guide.

Read from the UK Trade Tariff on 1 October 2026, the selected lines carry 2% duty for goods from China. The digital valve controller and listed gas-panel lines have a 0.00 % autonomous suspension, subject to their descriptions and the recorded exclusion for mixtures, preparations or products made up of different components containing these products. No anti-dumping or countervailing measures are recorded. The digital valve controller line also attaches a supplementary-unit import measure; confirm the declaration entry with your broker.

The UK Trade Tariff attaches import control of fluorinated greenhouse gases to these lines. Products containing banned fluorinated gases must not be placed on the Great Britain market. The precise import requirement for your controller is not established here: confirm it with your customs broker, supplying its gas contents and intended use. Confirm the commodity code before relying on a suspension.

Specify the fluid, calibration and control loop

State the gas or liquid, composition, flow range, operating pressure, temperature, wetted materials and seal compatibility. For gas controllers, agree the reference conditions used to express flow and whether calibration uses the actual gas or a conversion from another gas. Define accuracy against reading or full scale, repeatability, response behaviour and the valve's shut-off performance.

Agree the power supply, connector pin assignment, communication interface, mounting orientation and behaviour after loss of power or signal. Electromagnetic compatibility rules apply to electrical and electronic equipment liable to generate electromagnetic disturbance, subject to exceptions. For models in scope, importers must check the manufacturer's conformity assessment and provide importer identification and a postal address, with alternative placement where equipment marking is not possible. Ask for model-matched compliance evidence before ordering.

Worked duty example

Illustrative example, not a quote: Illustrative small-business batch of automatic mass-flow controllers under 9032 89 00 90, invoiced at £10,000 free on board, with £900 of freight and insurance to the UK. The customs value is £10,900. Duty at 2% is £218. Import VAT at 20% is charged on the customs value plus duty, £11,118, so it is £2,223.60. Import taxes total £2,441.60; a VAT-registered importer can usually reclaim the VAT, so the lasting cost is the £218 of duty. The import duty and VAT guide explains each step.

Inspection checklist

Calibration: match each serial number to its calibration record, fluid, range and reference conditions. Compare indicated and delivered flow against a calibrated reference across the agreed operating range.

Valve and seals: test shut-off leakage, external leakage and stable control at the intended pressure difference using a suitable safe test fluid. Inspect fittings, seals and capped ports for damage or contamination.

Integration: check connectors, pin assignments, communications and set-point response on the intended control system. Test restart and signal-loss behaviour against the approved specification.

Arrival condition: inspect packaging, ports and labels, then repeat functional checks before installation. Match compliance documents and importer details to the supplied model. Use quality inspection to organise these checks.

What goes wrong

A controller calibrated for a different gas or different reference conditions can report plausible flow while delivering the wrong amount. Confusing accuracy against full scale with accuracy against reading can also hide poor performance at low flow. Require the supplier to state the calibration basis and acceptance method in the purchase specification.

An unsuitable valve size or pressure difference can cause hunting, slow response or failure to reach the set point. Incompatible seals can leak, and reversed flow direction or mismatched connector wiring can prevent operation. Test the approved sample in your process conditions before accepting production.

Cambridge China Bridge sources these products for UK businesses, checking the factory and the documents before shipment. See factory verification. For components and parts, see sourcing for manufacturers.