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Engineering Reference Library

Industry Reference Cases

Engineering reference case profiles spanning the industries LONGWELL supplies — from AI data center CRAH FanGrid retrofit to battery gigafactory ATEX dust collection. Each profile documents the engineering challenge, solution architecture (LONGWELL SKU BOM), measured outcomes, and engineering lessons.

21 Case Profiles
2018–2026 Project record
2026 Last Updated
Evidence from the field

What our fans look like once they leave the factory

Everything here came out of our own project records. Twenty-seven of the thirty-five frames were taken by our own engineers on visits to customer plants; the other eight were photographed by customers and sent back to us. Nothing was staged and nothing was shot in our own showroom — every card says which of the two it is. We publish it because a fan sitting inside somebody else’s appliance says something a studio shot cannot.

Photographed by the customer and sent to usPhotographed by our engineer at the customer’s plant

We grade what we have, and the scale stops where our evidence stops. “Installed” is the last rung we can prove — our fan fitted in the machine the customer builds. We deliberately do not publish a “running on site” tier: photographs of a commissioned machine in a building belong to the people who own that building, and we only take them when they ask us to.

2,000+photographs on file
400+video clips on file
35cleared for publication

Why you are only seeing 35

Our project records hold more than 2,000 photographs and some 400 video clips taken in customer correspondence and on engineering visits, going back to 2018. Very little of it can be published as it stands. Most frames carry a customer’s name, brand, drawing, price or face. A great deal was sent to us in confidence about one specific project, and stays that way. Some of it is not even our equipment — competitor samples customers sent us to measure against. What is below is what survives all of that: the frames we can clean without destroying them and release without breaking a confidence. The set grows as more is cleared.

Frames where our nameplate or shipping mark is legible — 6 of 35

Forward-curved EC fan nameplate photographed by the customer the plate reads LONGWELL, Ningbo Longwell Electric TecPhoto from the customer
Forward-curved EC fan nameplate photographed by the customer — the plate reads LONGWELL, Ningbo Longwell Electric Technology: 220–240 VAC, 1,300 rpm, CE and EAC.L2 · United Kingdom · 2024 · LWFC-EC160SS-01
Nameplate as read by the customer on arrival the plate reads LONGWELL, Ningbo Longwell Electric Technology: DC CROSPhoto from the customer
Nameplate as read by the customer on arrival — the plate reads LONGWELL, Ningbo Longwell Electric Technology: DC CROSS FLOW FAN, 24 VDC 0.45 A, 2,400 rpm, CE and EAC, QC PASS, build date 2026.08.L2 · Poland · 2026 · LWCD-40700MN-06
EC centrifugal fan unpacked on site, the LONGWELL nameplate readable including the 2025.04 build date.Photo from the customer
EC centrifugal fan unpacked on site, the LONGWELL nameplate readable including the 2025.04 build date.L2 · 2025 · LWFE3G133-072SS-02
The crate label is ours manufactured by Longwell photographed in the customer s own vehicle: 2 pcs, N.WPhoto from the customer
The crate label is ours — manufactured by Longwell — photographed in the customer’s own vehicle: 2 pcs, N.W. 15 kg / G.W. 25.6 kg, 97.5 × 50 × 30 cm, CE and EAC.L1 · 2026 · LWCE-150700SN-06
Close-up of a LONGWELL fan module being wired up by hand during a customer visit: the nameplate on the black housinShot at the customer’s plant
Close-up of a LONGWELL fan module being wired up by hand during a customer visit: the nameplate on the black housing reads LONGWELL and carries the EAC mark, DC 24 V and 0.14 A. The impeller sits behind the mesh outlet grille and is not visible in this frame; a second identical module lies alongside on the table.L2 · Europe · 2023
Customer warehouse, brick-built: several crates of long cross-flow assemblies with LONGWELL marks carrying CE and EPhoto from the customer
Customer warehouse, brick-built: several crates of long cross-flow assemblies with LONGWELL marks carrying CE and EAC.L1 · Russia · 2024

The rest — what the inside of these machines actually looks like. From our European customer visits, December 2023 unless dated otherwise.

An electric fireplace running on the customer s bench with its flame effect litShot at the customer’s plant
An electric fireplace running on the customer’s bench with its flame effect lit. The silver cross-flow barrel and its motor sit on the top deck with the control board beside them — this is the convection path that carries the heat out of the appliance while the flame stays decorative.L4 · Europe · 2023
An over-door terminal in service in a commercial interior: finned coil above, quartz radiant elements behind mesh gShot at the customer’s plant
An over-door terminal in service in a commercial interior: finned coil above, quartz radiant elements behind mesh guards below, terminal block on the left carrying the usual L / N / PE marking. The cross-flow fan sits behind the coil and is not in frame.L4 · Europe · 2023
Four double-inlet centrifugal fans mounted on the base frame of a cast-resin dry-type transformer, inside a fencedPhoto from the customer
Four double-inlet centrifugal fans mounted on the base frame of a cast-resin dry-type transformer, inside a fenced substation bay. Cable routing and brackets are still in progress — this is the retrofit as it was actually being carried out, not a finished showcase.L4 · Israel · 2024
A centrifugal blower fitted into a stainless air-curtain housing on the customer s assembly line, protective film sShot at the customer’s plant
A centrifugal blower fitted into a stainless air-curtain housing on the customer’s assembly line, protective film still on the panels and the wiring boxes not yet closed. Photographed mid-build on a LONGWELL engineering visit.L4 · Europe · 2023
The same class of unit opened up: two cross-flow barrels driven from a shared centre motor, the control board and tShot at the customer’s plant
The same class of unit opened up: two cross-flow barrels driven from a shared centre motor, the control board and the harness laid out along the base. This is the layout decision — twin barrel, centre drive — that sets the length a door can cover.L3 · Europe · 2023
A customer photograph of an EC cross-flow retrofit, marked up by LONGWELL engineering and sent back to them: the foPhoto from the customer
A customer photograph of an EC cross-flow retrofit, marked up by LONGWELL engineering and sent back to them: the four screws that hold the motor to the housing, so their own technician could do the swap.L3 · Europe · 2025 · LWCE-150700SN-06
Two cross-flow fan assemblies laid out beside a finished convector on the customer s bench, with spare grille sectiShot at the customer’s plant
Two cross-flow fan assemblies laid out beside a finished convector on the customer’s bench, with spare grille sections stacked behind. The barrels are matched to the coil length, not the other way round.L2 · Europe · 2023
A pair of double-inlet centrifugal blowers next to the moulded housing they go into, still in their packagingShot at the customer’s plant
A pair of double-inlet centrifugal blowers next to the moulded housing they go into, still in their packaging. The perforated top plate is the customer’s own appliance design; the fans underneath are what they buy in.L2 · Europe · 2023
Unboxing at the customer: the fan on its bubble wrap while the lead colours are checked against the wiring definitiPhoto from the customer
Unboxing at the customer: the fan on its bubble wrap while the lead colours are checked against the wiring definition before fitting.L2 · 2025
A fully assembled cross-flow (tangential) fan long drum impeller in a sheet-steel frame, with an end-mounted externShot at the customer’s plant
A fully assembled cross-flow (tangential) fan — long drum impeller in a sheet-steel frame, with an end-mounted external-rotor motor and a galvanised mounting foot — on the workbench of a customer's assembly shop, with the customer's finned heat-exchanger coils and convector components staged alongside.L2 · Europe · 2023
Round-frame axial fans five sickle-shaped blades on a large external-rotor hub, with loose lead wires and a wire fiShot at the customer’s plant
Round-frame axial fans — five sickle-shaped blades on a large external-rotor hub, with loose lead wires and a wire finger guard on one unit — unpacked from a plain carton and stacked on the floor during a customer site visit in Europe, December 2023.L2 · Europe · 2023
Close-up of a compact metal-framed axial fan with a five-blade impeller and lead wires, unpacked and held for inspeShot at the customer’s plant
Close-up of a compact metal-framed axial fan with a five-blade impeller and lead wires, unpacked and held for inspection next to shipping cartons during a 2023 customer visit. No rating plate is visible in this frame, so the fan's make is not identifiable from the photo.L2 · Europe · 2023
Close-up of a black plastic centrifugal blower wheel with an integrated motor and red/black lead wires, held in hanShot at the customer’s plant
Close-up of a black plastic centrifugal blower wheel with an integrated motor and red/black lead wires, held in hand beside a customer's assembly bench during our December 2023 customer visits in Europe; white sheet-metal unit panels, mounting screws, an earth wire and a second fan are visible in the background.L2 · Europe · 2023
Hands-on inspection of a long tangential (cross-flow) fan impeller across the desk during a customer visit in EuropShot at the customer’s plant
Hands-on inspection of a long tangential (cross-flow) fan impeller across the desk during a customer visit in Europe, December 2023. The drum of forward-curved blades, its intermediate support ring and the stub shaft are clearly visible; the impeller carries no readable nameplate in this frame, so its make is not identified here.L2 · Europe · 2023
On-site service work on an electric fireplace: the opened unit exposes its installed cross-flow (tangential) blowerShot at the customer’s plant
On-site service work on an electric fireplace: the opened unit exposes its installed cross-flow (tangential) blower alongside the heating element and control board, while a second bare cross-flow fan assembly is on hand beside it for the swap. No nameplate is legible in the frame, so the fans shown are not identified by brand.L3 · Europe · 2023
An air-curtain body opened up on a workshop floor, with the front panel removed to expose the internals: two long cShot at the customer’s plant
An air-curtain body opened up on a workshop floor, with the front panel removed to expose the internals: two long cross-flow (tangential) impellers on a common axis, a central external-rotor motor on a sheet-metal bracket, the run capacitor, thermal cut-outs and the control board.L3 · Europe · 2023
On site at a customer workshop during our December 2023 European customer visit: a technician prepares a panel-mounShot at the customer’s plant
On site at a customer workshop during our December 2023 European customer visit: a technician prepares a panel-mount speed potentiometer and resistor for fan speed control, with an unpackaged backward-curved centrifugal impeller resting on the workbench beside him.L3 · Europe · 2023
Two slim finned convector elements set up on an office desk for a powered bench check: a small fan drive motor withShot at the customer’s plant
Two slim finned convector elements set up on an office desk for a powered bench check: a small fan drive motor with its terminal block and lead wires sits at the end of the front element, the wires running down off the table edge, while a hand connects a power lead beside the PC.L3 · Europe · 2023
A customer's fan-assisted trench convector opened up during our 2023 visit: the linear grilles have been lifted offShot at the customer’s plant
A customer's fan-assisted trench convector opened up during our 2023 visit: the linear grilles have been lifted off, exposing the finned water coil, the brazed copper/brass connection set, and a cross-flow (tangential) fan drum seated in the air channel with its vented motor box at one end.L4 · Europe · 2023
A customer's compact filtration appliance opened on the assembly bench: two backward-curved centrifugal impellers wShot at the customer’s plant
A customer's compact filtration appliance opened on the assembly bench: two backward-curved centrifugal impellers with external-rotor motors are seated in the unit's acoustically lined fan chambers, with the louvred top cover lifted away.L4 · Europe · 2023
End view of a slim black convector cabinet with its end cover opened, revealing the sheet-metal blower housing andShot at the customer’s plant
End view of a slim black convector cabinet with its end cover opened, revealing the sheet-metal blower housing and its circular air inlet mounted inside the unit, with the supply cable led out to the floor.L4 · Europe · 2023
Cut-away view inside a wall-mounted convector: a finned heat-exchanger coil above, and beneath it two tangential (cShot at the customer’s plant
Cut-away view inside a wall-mounted convector: a finned heat-exchanger coil above, and beneath it two tangential (cross-flow) fan barrels in line behind an expanded-metal guard, with the motor mounting bracket visible where the two barrels meet.L4 · Europe · 2023
A cross-flow (tangential) fan assembly with an external-rotor motor, seated in the cut-out of a linear trench-conveShot at the customer’s plant
A cross-flow (tangential) fan assembly with an external-rotor motor, seated in the cut-out of a linear trench-convector housing on a customer's assembly bench in Europe, December 2023.L4 · Europe · 2023
A floor-trench convector opened up for inspection on its pallet during a customer site visit: the linear bar grilleShot at the customer’s plant
A floor-trench convector opened up for inspection on its pallet during a customer site visit: the linear bar grille lifted off to the left, the finned water coil in the middle, and a cross-flow (tangential) fan drum running behind its wire guard along the right-hand side, with the wiring compartment and two round duct spigots also visible.L4 · Europe · 2023
Inside a customer's long linear terminal unit with the cover removed: a cross-flow (tangential) impeller and its enShot at the customer’s plant
Inside a customer's long linear terminal unit with the cover removed: a cross-flow (tangential) impeller and its end-mounted drive motor sit in the black sheet-metal housing, with the scroll cut-off, discharge grille, flexible wiring conduit and lever-type wire connectors all visible, and a second cross-flow module in the adjacent section of the same chassis.L4 · Europe · 2023
Cut-away display units at a customer showroom: a fan-assisted trench (floor) convector opened up to show two tangenShot at the customer’s plant
Cut-away display units at a customer showroom: a fan-assisted trench (floor) convector opened up to show two tangential cross-flow impellers seated in the black fan scroll above the finned heat exchanger, with the motor and wiring harness at the right-hand end.L4 · Europe · 2023
An electric-fireplace unit opened up on the customer's floor during a December 2023 visit: a cross-flow (tangentialShot at the customer’s plant
An electric-fireplace unit opened up on the customer's floor during a December 2023 visit: a cross-flow (tangential) fan is mounted across the chassis above the lit flame-effect chamber, wired to the unit's control board.L4 · Europe · 2023
Three tangential (cross-flow) fan modules bolted onto a fabricated steel mounting rail with a sheet-metal outlet plShot at the customer’s plant
Three tangential (cross-flow) fan modules bolted onto a fabricated steel mounting rail with a sheet-metal outlet plenum and a cable-tied wiring harness, photographed in a customer's workshop during our December 2023 visit.L4 · Europe · 2023
A backward-curved centrifugal impeller mounted behind the inlet cone inside a sheet-metal air-handling cabinet, phoShot at the customer’s plant
A backward-curved centrifugal impeller mounted behind the inlet cone inside a sheet-metal air-handling cabinet, photographed through the open access panel. Protective film, drilling swarf and a cable being routed out of the panel show the unit still under assembly on site; no maker's nameplate is visible in this frame.L4 · Europe · 2023

Customer names, brands, addresses, delivery notes and prices are removed, faces are pixelated, and location metadata is stripped from every file before upload. Where a photograph could only be cleaned by destroying it, we left it out. Where the fan itself is not visible in frame, the caption says so rather than implying it. Countries are given only where they add engineering context.

Send us your duty pointSee the 21 engineering case profiles ↓
About these case profiles: Each profile is an anonymized composite reference based on representative LONGWELL platform deployments in that industry segment. They are not specific named customer references. Specific customer references and project PDFs are available under NDA on qualification (sales@longwellfans.com).

All Case Profiles

01

Trench Convector & Heating Terminal Fans

Trench Convectors & Hydronic Heating Terminals · Ø30–Ø65 mm DC 0–10 V Cross-Flow Programme Compiled from LONGWELL’s real project correspondence with trench-convector, floor-co…

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02

Wind, Solar & Inverter Cooling

Wind turbine cabinets and PV inverters: 8,755 m3/h at 845 Pa, dual 0-10VDC and 4-20mA control, factory testing witnessed on video against agreed limits, and a committed 1,000 pcs/month reserve line.

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03

Range Hoods, Ovens & Fan Coils

Range hoods, ovens and fan coil terminals: 150 rpm minimum speed for Eurovent testing, 50 Hz variants built to order rather than shipped from default stock, REACH/RoHS declarations and third-party factory audit.

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04

Drying, Heat Treatment & Ovens

Fans for industrial drying, heat treatment and ovens: 500 W-class EC second-source qualification against incumbent European fans, ball bearings for continuous radiant heat, PLC 0-10V with tachometer feedback, CE LVD and EMC on f…

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05

Telecom & Power Cabinet Cooling

Cooling for telecom cabinets, industrial power cabinets and PV inverter stations: 3,900 m3/h measured de-rated to a 290 W ceiling, 48 V DC bus, reliable start at -30C, 40,000 h life, IP44/IP55.

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06

Consumer Air Cooler & Fan ODM

Consumer Air Coolers, Tower Fans and Handheld Fans · ODM Programmes for European Retail Compiled from LONGWELL’s real correspondence with European household-appliance brands and retail groups. This segment buys fini…

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07

OEM Fan Components

OEM Component Supply · Impellers, Bare Motors, Shafts and Bearings to Drawing The largest single segment in LONGWELL’s own correspondence is not a finished-fan application at all — it is component supply to ma…

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08

AHU & Ventilation Unit Fans

Engineering Reference Case Profile · AHU and Ventilation Units AHU and Ventilation Units · EC Plug Fans, Wide Turndown, Potted Electronics Compiled from LONGWELL’s real correspondence with air-handling-unit b…

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09

Dry-Type Transformer Cooling

Dry-Type Transformer Forced-Air Cooling · Cross-Flow Assemblies, Mounting Beams and EC Upgrades Compiled from LONGWELL’s real correspondence with dry-type transformer, AVR and high-voltage equipment manufacturers. W…

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10

Rail & Vehicle HVAC Fans

Rail and Vehicle HVAC · Wide-Temperature EC Fans, High Static Pressure in a Small Frame Compiled from LONGWELL’s real correspondence with rolling-stock HVAC builders, bus and special-vehicle climate system manufactu…

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11

Air Curtain OEM Programme

Air Curtain OEM Programme · Cross-Flow Barrels, Impellers and the EC Axial Upgrade Path Compiled from LONGWELL’s real correspondence with air-curtain manufacturers in Turkey, Russia, Ukraine and the UAE. Air-curtain…

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12

Use Cases: BESS

Engineering Reference Case Profile · Hyperscale Air-Cooled Container 4 MWh Air-Cooled BESS Container Thermal · Hyperscale Utility A composite reference case based on representative hyperscale utility-scale BESS dep…

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13

Vertical Farm LED HVAC

Engineering Reference Case Profile · 8,000 m² Urban Vertical Farm 8,000 m² Vertical Farm LED Hot-Zone HVAC · 720 EC Fans A composite reference case based on representative urban vertical farming facility builds — supplying anti-…

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14

FFU

Engineering Reference Case Profile · New-Build Logic Fab FFU Fit-Out 22,000 FFU at ISO Class 5 · Logic Fab Fit-Out A composite reference case based on representative new-build semiconductor logic fab FFU fit-out projects — suppl…

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15

Smart Home ERV

Engineering Reference Case Profile · Asia Smart Home Brand 80k-Unit Program 80,000-Unit Smart-Home ERV Product Launch · Matter 1.2 A composite reference case based on representative Asia smart-home brand ERV launch programs — su…

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16

Cleanroom Build

Engineering Reference Case Profile · GMP Grade A/B mRNA Manufacturing 800 FFU mRNA Fill-Finish Cleanroom Build · EU GMP Annex 1 A composite reference case based on representative mRNA pharma fill-finish facility builds — supplyi…

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17

Battery Cathode Powder Dust Collection

Engineering Reference Case Profile · Battery Gigafactory ATEX Dust Collection Battery Cathode Powder Dust Collection · Gigafactory ATEX IIIC A composite reference case based on representative battery gigafactory cathode/anode du…

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18

Heat Pump Fan Program

Engineering Reference Case Profile · Asia-Pacific R290 OEM Volume Program 50,000-Unit R290 Monobloc Heat Pump Fan Program · 12 kW Class A composite reference case based on representative R290 monobloc heat pump OEM programs in t…

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19

350 kW Charger Cabinet Cooling

Engineering Reference Case Profile · 350 kW Liquid-Cooled DCFC OEM 5,000-Station 350 kW Ultra-Fast Charger Cabinet Cooling A composite reference case based on representative 350 kW liquid-cooled ultra-fast DCFC OEM programs — su…

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20

CRAH FanGrid Retrofit

Engineering Reference Case Profile · Tier 3 Colocation Retrofit 50-Fan CRAH FanGrid Retrofit · 2 MW Tier 3 Colocation A composite reference case based on representative CRAH FanGrid retrofit projects in the colocat…

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21

Cold Chain Supermarket

Engineering Reference Case Profile · 200-Store Retail Retrofit 200-Store Supermarket Display Case Evaporator Retrofit A composite reference case based on representative supermarket chain retrofit programs — replacing legacy AC e…

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