A UV coating machine applies a liquid coating to a sheet or web and cures it under UV lamps. The air systems around it do three jobs: exhaust the fumes and ozone the curing produces, hold down the sheet as it moves, and sometimes assist drying or cooling. Each is a distinct blower duty. This guide separates them and shows which Yash Blowers machine fits, because the common mistake — one undersized fan trying to do everything — leaves the operator breathing ozone and the sheets lifting.
The three air jobs on a UV line
| Job | Air character | Machine |
|---|---|---|
| Fume / ozone exhaust from the UV tunnel | High volume, low-medium pressure | Centrifugal blower |
| Sheet / web hold-down | Moderate vacuum, meaningful flow | Regenerative blower (vacuum) |
| Cooling / drying assist | High volume, low pressure | Centrifugal / regenerative |
Fume and ozone exhaust — the safety-critical duty
UV curing generates ozone and drives off coating volatiles. That air must be pulled out of the curing tunnel and ducted away from the operator, continuously and reliably. It is a high-volume extraction duty against the modest static pressure of the tunnel and duct run — a centrifugal job. The CX-Series Centrifugal Blower covers it; the YBCB-CX-125A moves roughly 1,950–2,350 m³/hr, and the YBCB-CX-100A suits smaller tunnels at 1,200–1,450 m³/hr.
Treat this as safety equipment, not an optional extra. Size it to keep the tunnel under negative pressure so fumes never spill into the room, and design the duct so exhaust discharges safely outside. The extraction sizing method is the same as any dust or fume collection system: volume from air changes, pressure from duct and any filter.
Sheet and web hold-down
As the substrate passes the coating head and under the lamps, it needs to stay flat. A vacuum bed or belt holds it — moderate vacuum, decent airflow, exactly the duty a Single Stage Turbine Blower in vacuum mode serves. The YEBL-1-270 pulls around -230 mbar with the flow to cover open belt holes. This is the same principle as a screen-printing vacuum table, and the sizing rules there apply here too — size airflow for the worst-case leakage.
Where a firmer, oil-free hold at lower flow is wanted on non-porous film, a High Vacuum Pump such as the ACME-040 gives deeper vacuum for a tightly sealed bed.
Cooling and drying assist
After the lamp, sheets can run warm; some lines add a cooling blow-off before stacking. This is a high-volume, low-pressure duty that a centrifugal blower or a regenerative blower feeding an air knife handles.
Sizing checklist
- Exhaust first, and generously. Under-sizing the ozone/fume extraction is a health issue. Size for the tunnel volume, keep it under negative pressure, and run it whenever the lamps are on.
- Hold-down for worst-case leakage. Size the vacuum blower for the smallest sheet and the most open belt holes, not a sealed test port.
- Separate the machines. Do not tap hold-down vacuum off the exhaust fan or vice versa — the pressures and directions are different.
- Filter and protect. Coating mist and dust in the exhaust and hold-down air will foul an impeller; fit and maintain inlet filters and keep the wet zone away from the machines.
Environment notes
UV coating halls carry solvent vapour and ozone. Site the blowers so their cooling air is clean, keep motors clear for heat dissipation, and where the atmosphere is aggressive, discuss suitable construction at the enquiry stage. On multi-shift lines, treat the exhaust blower as critical and consider a standby.
The hold-down logic mirrors our screen-printing tables post, and the extraction logic mirrors textile waste collection. The full duty list is on our UV coating application page.
The exhaust duty in more detail
The fume and ozone exhaust deserves the most care because it is the safety system. UV curing produces ozone from the air near the lamps and drives off volatiles from the coating. Both must leave the tunnel and be discharged safely, and the tunnel should sit under slight negative pressure so nothing spills toward the operator.
Size it as an extraction duty:
- Volume comes from the tunnel air changes needed to sweep out fumes at line speed — a bigger or faster tunnel needs more.
- Pressure comes from the tunnel entry/exit losses, the duct run to the discharge point, and any exhaust filter.
- Reliability is non-negotiable — the exhaust runs whenever the lamps are on, and an interlock so lamps cannot run without extraction is good practice.
The CX-Series Centrifugal Blower handles most tunnels; step up within the range for longer ducts or larger tunnels.
| Exhaust design point | Consequence if wrong | Get right by |
|---|---|---|
| Tunnel negative pressure | Fumes spill to operator | Size volume for full air changes |
| Duct to safe discharge | Ozone recirculates | Route and size the duct properly |
| Runs with lamps | Exposure during warm-up/run | Interlock exhaust to lamps |
| Filter (if fitted) loading | Airflow fades over time | Size for loaded condition |
A worked example: hold-down on a sheet-fed coater
Take a sheet-fed UV coater with a vacuum belt holding board as it passes the head and lamps. The board leaves belt holes exposed at the edges:
- Airflow. Size for the worst case — narrowest board, most open belt holes — so hold-down does not sag on small work.
- Vacuum. Moderate, enough to keep the board flat and registered.
- Model. A YEBL-1-270 (3.0 HP) in vacuum mode covers a typical belt; a sealed film bed wanting deeper vacuum suits an ACME-040.
Frequently asked questions
Can the exhaust fan also do hold-down? No — one is high-volume pressure extraction, the other is moderate vacuum with flow. Different curves, different machines.
How much exhaust is enough? Enough to keep the tunnel under negative pressure at full line speed so no fume escapes. When in doubt, size up — this is a safety duty, not an efficiency one.
Installation and safety habits
Because the exhaust is a safety system, the install deserves discipline:
- Interlock exhaust to the lamps. The extraction blower should run whenever the UV lamps are energised, including warm-up, so no cycle ever runs without fume removal.
- Keep the tunnel under negative pressure. Size and set the exhaust so air flows into the tunnel at the openings, never out toward the operator.
- Discharge safely. Route the exhaust duct to a proper outside discharge, not back into the workspace, and size the duct so it does not throttle the fan.
- Separate hold-down and exhaust machines. They are different curves — do not tap one off the other.
- Filter and protect intakes. Coating mist and dust foul impellers; fit and maintain inlet filters and keep the wet coating zone away from the machines.
- Standby on the exhaust for multi-shift lines — an exhaust failure is a stop, not just an inconvenience.
Treat the exhaust as production-and-safety-critical and the hold-down as quality-critical, size each to its worst case, and the line runs clean and safe through every shift.
Get the exhaust and hold-down sized
Tell us your tunnel size, sheet dimensions and line speed, and we will size the ozone/fume exhaust and the hold-down vacuum to match — safely. WhatsApp +91 9311693322 or email sales@yashblowers.org for a quote in 24 hours.