QIYUE FAN / REPLACEMENT PLANNING
Site Airflow Survey Before Fan Replacement: Agree the Measurement Scope
A single air-speed reading is not a complete fan-duty record. Commission a survey that connects the measured airflow to its location, operating case and pressure basis before using it to purchase replacement equipment.
Fan tag, duct plane and active branches
Method, readings, instrument and air conditions
Operating case, pressure basis and required change
Specify the question the survey must answer
Decide whether the work is intended to establish the existing fan duty, diagnose a reported shortage, record branch distribution or provide an acceptance benchmark. These are related tasks, but their measurement boundaries and deliverables may differ.
For a replacement RFQ, identify both the present operating case and the future requirement. A reliable measurement of today’s system does not establish the airflow needed after a new production line, hood or filter is added.
Ask for a measurement plane, not just a number
Fluke’s duct-traverse guidance describes measurements at multiple positions across a duct section and recommends suitable straight duct away from disturbances. The internal duct dimensions and measurement arrangement form part of the result.
Ask the surveyor to mark the actual plane on a sketch and retain its dimensions, nearby fittings and access limitations. A reading at an open grille, a branch and the main duct should not be labelled as the same measurement without explaining the relationship.
The responsible specialist should select the method, instrument and sampling arrangement for the real air conditions and access. Arrange safe test access through the site’s procedures; do not open guarded machinery or create test holes in an operating hazardous system to follow a general guide.
Keep the conditions attached to every result
Equipment and controls
Record the fan identification, actual fan speed or its evidence, damper positions and the active equipment combination. Distinguish a VFD command from a measured shaft speed.
Air and process
Keep temperature, gas information and the stated flow basis with the measurement. Record relevant filter and process condition, rather than comparing a cleaned system with a loaded production case as though nothing changed.
Method and instrument
Retain the individual readings and calculation output, instrument identification, calibration evidence and any limitations the surveyor reports. Fluke notes that its described meter’s calculation uses a defined standard-air basis; ask what basis the instrument and report actually use.
Request a report that can support a buying decision
The replacement supplier needs the measurement result together with the selected pressure locations and pressure type, the system sketch and the operating case. Label missing pressure or speed data openly rather than estimating it from motor size.
Agree the required report and acceptance responsibility before the visit. Ask the surveyor to distinguish observations, calculated values and conclusions. Where access or flow conditions limit confidence, the report should explain what further work is needed rather than present an unsupported pass or fail.
For local exhaust ventilation, total flow alone does not demonstrate adequate contaminant control. HSE’s commissioning guidance calls for the operating conditions, test methods, performance at individual hoods and a schematic identifying test points. Keep the process-control assessment alongside the fan-duty record.
Use the findings in the correct review
If readings disagree with the selected curve, start with the installed low-airflow review. For a supplied laboratory document, use the separate performance test report guide. A site survey and a laboratory report are not automatically interchangeable.
Send the survey with your replacement enquiry
Include the complete report, current fan identification, installation photos and the change you want the replacement to achieve. Available records can start the discussion even when further measurements are needed.
References: Fluke duct-traverse guidance; HSE LEV commissioning guidance.