When the gas is hot enough to anneal mild steel, ordinary fan engineering stops working. The shaft elongates and binds the bearings. The casing grows and cracks rigid joints. Bearing housings cook in their own conducted heat. We build hot-gas fans for kilns, furnaces, RTOs, heat-treatment lines, secondary steel-making and glass-melting — to the full 600 °C continuous ceiling, higher with refractory lining or transient pulses, across the envelope below.
On a hot-gas fan the duty point is the easy part. The real engineering is what happens to the metal at temperature: it loses strength, it grows, and it conducts heat into the bearings. Each of the three drives a different design choice.
At 600 °C mild steel keeps only ~40% of its room-temperature yield. Blade thickness, geometry and speed must be sized so centrifugal stress at temperature — not at 20 °C — stays inside allowable limits.
A 1 m shaft elongates ~7 mm from cold to 600 °C; a 2 m casing grows ~14 mm. Bearings, foundation, ducting and access doors all have to take that movement without binding, cracking or leaking.
Heat flux travels the shaft and casing into the bearing housings. Above 100 °C at the housing the lubricant breaks down and the bearing fails — so the design has to actively carry heat away from that zone.
High temperature attacks the rotating wheel, the static casing and the bearing end of the shaft in three different ways. Design for each, and the fan holds shape through repeated heat-up cycles. Design for the duty point alone, and it creeps, cracks or cooks within the first 12–24 months.
Thin, efficient backward-curved blades lose strength and slowly creep out of shape above ~482 °C, throwing the rotor out of balance.
How we engineer it outWheel type shifts toward rugged radial blades and the max speed is derated; impeller metallurgy steps up the creep ladder — Cr-Mo (16Mo3, 2.25Cr-1Mo) or stabilized austenitic 304H / 321 / 347 by temperature band.
Carbon steel reaches its oxidation limit at ~482–510 °C and the casing scales; rigid joints crack as the casing grows ~14 mm across a 2 m diameter.
How we engineer it outCasing metallurgy follows its own oxidation ladder (Cr-Mo, austenitic 304 / 321, 310S, then refractory lining); fabric or metal expansion joints at inlet and outlet absorb the growth, and the foundation lets the casing slide without cracking the grout.
Conducted heat raises the bearing housing past the lubricant rating; left unmanaged the shaft binds and the bearing seizes.
How we engineer it outBearings move outside the airstream above ~120 °C; air-cooled shaft and heat slinger from ~482 °C, water-cooled above ~1010 °C; water-cooled housing recommended above 200 °C.
We don't sell a catalogue near-fit. The fan is engineered to your gas temperature — continuous and transient — its composition, particulate and operating point, with two separate material ladders for the wheel and the casing.
No catalogue fan forced onto your spec. Your operating point is engineered onto the best-efficiency region of the selected wheel and corrected for hot density — then verified on the 200 HP VFD test rig as a cold-air equivalent test, with hot-gas operation extrapolated by fan-law correction before dispatch.
| Parameter | Standard | On application |
|---|---|---|
| Volume flow | up to 2,00,000 CMH | higher on enquiry |
| Static pressure | up to 2,000 mmWC | higher on enquiry |
| Continuous operating temperature | up to 600 °C | higher with refractory lining + special metallurgy |
| Transient / startup pulses | up to 750 °C short duration | higher with engineered protection |
| Drive power | up to 400 HP | higher with custom motor sourcing |
| Speed | 600–1,800 RPM typical, derated above ~482 °C | per duty + sound limits |
| Balance quality | ISO 21940 G6.3 | G2.5 / G1.0 on application |
| Bearing life (design target) | L10h ≥ 40,000 h continuous | longer L10 on application |
The envelope above covers the great majority of industrial hot-gas duty. Refractory liner is available 600 °C+ and standard above 700 °C; the shaft-cooling disc is standard above 350 °C. For duty beyond 600 °C continuous we engineer to spec — stepping the wheel and casing up their separate material ladders — and quote on enquiry.
The same engineering language carries from your enquiry to the GA drawing to the nameplate — expressed in the standard AMCA conventions, with the wheel and casing metallurgy called out separately.
| Specification field | Options |
|---|---|
| Arrangement (AMCA 99) | Arr. 1 / 8 (overhung, fan bearings outside the airstream) and Arr. 9 default for hot-gas duty; Arr. 4 (wheel on motor shaft) only up to ~120 °C, or ~230 °C with a special motor — selected by drive, access and temperature. |
| Width / inlet | SWSI (single width, single inlet) default for hot-gas duty; DWDI (double width, double inlet) with an inlet box for high flow at moderate pressure. |
| Wheel type | Backward-curved / airfoil up to ~482 °C (high efficiency); radial / forward-curved above ~482 °C where thin blades would creep — rugged radial blades hold shape, with the max speed derated. |
| Class (by pressure / outlet velocity) | Class I / II / III selected from the duty point on the pressure-vs-outlet-velocity limits; higher class = heavier construction for higher pressure and tip speed. |
| Materials — impeller (creep-limited) | MS / IS 2062 to ~250 °C; low-alloy Cr-Mo / 16Mo3 to ~500 °C; austenitic 304H / 321 / 347 to ~650 °C; 309 / 310 / 310S to ~870 °C; Inconel above ~1050 °C. |
| Materials — casing (oxidation-limited) | Carbon steel to its oxidation limit ~482–510 °C; Cr-Mo or austenitic 304 / 321 to ~650 °C; 310S to ~870 °C; refractory-lined steel casing above that — called out separately from the wheel. |
| Drive | Direct-coupled / V-belt / VFD. Drive up to 400 HP across the envelope; speed typically 600–1,800 RPM, derated above ~482 °C. |
| Accessories & high-temp scope | Fabric or metal expansion joints at inlet and outlet (growth ~7 mm/m of shaft at 600 °C); air- or water-cooled shaft + heat slinger; shaft cooling disc (standard above 350 °C); water-cooled bearing housing above 200 °C; carbon-ring seal with nitrogen purge; ceramic-fibre insulation / double-jacketed housing above ~537 °C; refractory lining and heat-up schedule; foundation drawings with the GA. |
Every job's performance is verified at our works on the 200 HP VFD test rig, to the AMCA 210 / ISO 5801 method, before dispatch.
Reheating-furnace flue gas, electric-arc furnace dedusting (post-cooling), sinter-plant ID, ladle-metallurgy fume extraction.
Kiln main-burner exhaust (pre-ESP), pre-heater fans, calciner ID, kiln-hood ventilation.
Cupola flue gas, induction-furnace fume, heat-treatment-furnace ID, forge-shop ventilation.
Float-glass furnace flue gas, oxygen-fuel-fired furnace exhaust, regenerator gas handling.
RTO hot-side fans, RCO recirculation, high-temperature process-boiler ID.
High-temperature solvent recovery and RTO fans for VOC abatement.
Kiln duty for non-ferrous metal processing and fly-ash handling post-boiler.
45 application/duty types engineered. Tell us your gas temperature.
What our marks mean, in the words that survive an audit.
Tested to the AMCA 210 / ISO 5801 method, in-house on our 200 HP VFD rig. Tested-to-method — not AMCA-certified.
ISO 9001:2015 — third-party certified. Our only third-party certification.
Self-declared per 2006/42/EC + 2014/35/EU (Module A). A self-declaration, not a notified-body certificate.
Self-declared, Zone 2/22, Category 3, per 2014/34/EU, where the area classification calls for it.
Designed and built to API 673 as project-specific scope.
ASME Sec IX qualified welders + WPS for every joint.
ISO 21940 — G6.3 minimum, G2.5 / G1.0 on application.
ISO 20816 evaluation; ISO 14694 for fan-specific limits.
| Stage | Standard duty | API-673 / engineered |
|---|---|---|
| Offer / quotation | 3 working days — always | 7–10 working days |
| GA drawing for approval | 2–3 weeks from PO | 3–4 weeks from PO |
| Manufacture + balance + paint | 6–10 weeks | 10–14 weeks |
| Performance test + witnessed FAT | ~1 week | 1–2 weeks |
| Order-to-dispatch (total) | 9–14 weeks | 14–20 weeks |
Shutdown-driven replacements: we have shipped fans within 6 weeks of a clean PO. Tell us your shutdown window and we commit to a dated plan.
The same engineering, viewed three ways — by fan family, by duty, and by industry. Follow the cross-references.
No model numbers needed. Give us the operating conditions — flow, static, gas temperature, composition, particulate, and any tender standard — and our application engineers size the fan and quote it. Attach a spec or GA if you have one.
+91 90110 09155 · mihir.jitamitra@gmail.com