Sourcing psychrometers from China

Duty and mercury controls

Read from the UK Trade Tariff on 30 September 2026, the relevant lines under heading 9025 carried 0% duty for goods from China, with no anti-dumping or countervailing duty and no listed suspensions. This heading covers psychrometers, thermometers, hygrometers and related instruments and parts.

The tariff attaches mercury import and export controls to the non-electronic instrument and liquid-filled thermometer lines, and a mercury export control to the electronic instrument line. Confirm the applicable restrictions and any exceptions for importing mercury measuring devices from China into Great Britain or supplying them there with the Environment Agency and your customs broker. Specify mercury-free liquids and obtain written confirmation from the factory; confirm any claimed exception before ordering.

A complete psychrometer and separately imported replacement thermometers may use different codes. Confirm the commodity code from the complete design, operating method and shipment contents. See the wider thermometers and hygrometers guide for other products within this heading.

Specify the bulbs, wick and airflow

Define whether the instrument is wall-mounted, sling-operated or aspirated. Agree the temperature range, scale divisions, reading tolerance, thermometer liquid, bulb protection and mounting arrangement. Request the humidity conversion table or calculation method supplied with the exact model, including its pressure assumptions.

Specify wick material, replacement availability, water reservoir design and the method for keeping the wet bulb wetted. For aspirated models, agree how airflow is produced and checked. For electronic versions, confirm with the relevant authority whether electromagnetic compatibility, battery and waste electrical equipment rules apply to the finished model, and obtain evidence for any applicable requirements.

Worked duty example

Illustrative example, not a quote: Illustrative order of 20 electronic wet and dry bulb psychrometers under 9025 80 40 89, invoiced at £5,100 free on board, with £900 of freight and insurance to the UK. The customs value is £6,000. Duty at 0% is £0. Import VAT at 20% is charged on the customs value plus duty, £6,000, so it is £1,200. With no duty, the only import tax is the VAT, which a VAT-registered importer can usually reclaim. The import duty and VAT guide explains each step.

Inspection checklist

Thermometers: compare the temperature readings against a calibrated reference across the agreed range; check scale alignment, legibility and continuity of the liquid columns.

Wick and water: check that the wick fits the wet bulb, wets evenly and stays supplied with water during the agreed operating procedure.

Airflow and humidity: test the instrument using its supplied instructions and conversion method, then compare the resulting humidity reading with a reference hygrometer.

Build and packing: check bulb guards, sling attachment or aspirator operation, reservoir leakage, spare wicks, instructions in English and protection against glass breakage.

What goes wrong

A dry, contaminated or poorly fitted wick undermines the wet-bulb reading. Insufficient airflow and readings taken before stabilisation can also distort the humidity result. Check the operating procedure with the sample rather than accepting a humidity claim based only on thermometer accuracy.

Mismatched thermometers, shifted scales and broken liquid columns can spoil otherwise sound instruments. A conversion table with unsuitable pressure assumptions creates another source of error. Agree acceptance criteria and retain the approved sample, instructions and conversion method for arrival checks.

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.