Local Capture
Place the hood or enclosure close enough to intercept the contaminant before it crosses the worker's breathing zone.
Whole-System Air Path
Factory Ventilation Planning Starts At The Source
Capture the source first, then balance general exhaust and make-up air. Add circulation only after the clean-to-dirty air path works.
1Capture At Source
2General Exhaust
3Replace The Air
4Circulate Carefully
Direct Answer
What Is The Right Order For Factory Ventilation Design?
Begin with contaminant source capture. Use general exhaust for the residual room load, supply clean replacement air to support those flows, and use circulation only where it helps the occupied zone without spreading the contaminant.
A fan count cannot define a factory system. Process emission rate, hood position, duct pressure, building pressure, climate, doors, heat, occupied zones and discharge location all interact. Exhaust without make-up air can starve the system; make-up air aimed at a hood can break capture; circulation between a source and workers can worsen exposure.
This page handles the complete air path. The existing factory airflow fan guide explains equipment roles; it should be used after the system sequence and inputs are clear.
Engineering scope and sources reviewed 4 October 2026 · Project conditions still govern final selection
Decision Framework
Give Each Device One Clear Job
Overlapping roles create false capacity and hard-to-diagnose complaints.
General Exhaust
Remove the residual heat or diluted contaminant that source capture cannot reasonably contain, using a defined room balance.
Make-Up Air
Supply clean air at a location, temperature and velocity that supports capture and keeps doors and combustion systems stable.
Room Circulation
Use HVLS or local air movement for mixing and comfort only after verifying it does not carry contaminants into clean or occupied zones.
Field Inputs
Map Every Flow Before Selecting Equipment
A one-page balance exposes missing inputs earlier than a list of fan models.
| System Element | Define | Verify |
|---|---|---|
| Source | Material, release point, rate, temperature and operating schedule | Capture at the source under normal and upset positions. |
| Hood/enclosure | Geometry, distance, cross-drafts and access | Containment or capture across the actual process envelope. |
| Duct/system | Length, fittings, filter/collector, damper and discharge | Pressure loss, leakage, cleaning access and safe discharge. |
| General exhaust | Residual heat/contaminant load and room zones | Room pressure and measured exhaust flow. |
| Make-up air | Outdoor source, amount, distribution and conditioning | No hood interference, door problem or short circuit. |
| Circulation | Occupied target, obstructions, process limits and controls | Useful air movement without contaminant migration. |
Boundary: Occupational exposure, fire, combustion, hazardous classification and discharge compliance require qualified project review; a website guide cannot set the final design.
Practical Sequence
Plan The Factory As A Connected Pressure System
- Inventory the sources.Record material, location, schedule, heat and contaminant form for every significant process.
- Capture what can be captured.Prefer enclosure or close capture before increasing room-wide exhaust.
- Calculate each branch.Determine required flow and pressure from hood through treatment and discharge.
- Balance the building.Add general exhaust and make-up air with a stated pressure objective and door condition.
- Place circulation last.Check HVLS and portable-fan paths against capture zones, clean zones and workers.
- Commission together.Measure capture, flow, pressure and occupied-zone conditions with all interacting systems in normal operation.
Connected Decisions
Use The Next Page Only When It Answers The Next Question
These links continue the same project workflow rather than sending the reader to loosely related content.
Understand Fan Roles
Use the existing factory guide to assign equipment after the complete air path is defined.
Calculate Exhaust Flow
Use volume/ACH only as one preliminary screen and include pressure and source-capture requirements.
Balance Make-Up Air
Set supply from the full airflow balance and commissioning pressure objective.
Compare Current Products
Review ceiling, portable and exhaust platforms without using the catalog as a system design.
Questions Buyers Actually Ask
Factory Ventilation Planning Questions
Is an HVLS fan a ventilation system?
No. It recirculates room air. It can support comfort or mixing but does not by itself provide outdoor air or remove a contaminant from the building.
Should I size factory exhaust by air changes per hour?
ACH can screen general dilution, but source capture, contaminant generation, heat, pressure and duct losses can govern. Do not use one universal ACH for every process.
Why does an exhaust fan perform poorly when doors close?
The building may lack a low-resistance replacement-air path. Measure room pressure and system flow rather than assuming a larger fan is the first fix.
Can portable fans improve ventilation?
They can move air locally, but placement can disrupt capture or spread contamination. Define the clean-to-dirty path before adding them.
Where should make-up air enter?
From a clean outdoor source and at a location and velocity that supports occupied zones and hoods without short-circuiting to exhaust or pressurizing sensitive rooms.
What must commissioning measure?
At minimum, verify source capture or containment, branch and main flows where applicable, room pressure, supply distribution, discharge condition and occupied-zone air movement under normal simultaneous operation.
Source Boundary
References Used For This Guide
Sources define methods and safety boundaries. They do not certify a proposed AirMoveX model or replace the adopted code, OEM instructions or a qualified project designer.
HSE
Controlling Airborne Contaminants at Work (HSG258)
A practical local-exhaust framework focused on source capture, design, commissioning and examination.
Open sourceOSHA
Ventilation, 29 CFR 1910.94
Requirements for covered industrial processes and ventilation arrangements.
Open sourceNIOSH
Industrial Ventilation Resources
Supports a hierarchy that distinguishes local exhaust from general room air movement.
Open sourceProject Review
Send The Process Map Before The Fan List
Share sources, hoods, duct routes, required flows, pressure losses, make-up air, doors, occupied zones and simultaneous operation. AirMoveX can align equipment roles without pretending one fan solves the whole system.