Jitamitra Electro Engineering Private Limited

27/08/2026

27/08/2026

"Backward-curved" is only half a specification.

Backward is a blade direction. Inside it sit three different blade sections — aerofoil, curved plate and flat plate — and each is a different machine for efficiency, for dust, and for how the wheel ends its life. Writing "backward-curved" in a spec without naming the section is like ordering steel without a grade.

The aerofoil is a hollow, wing-section blade, and the hollow is the trap: in particulate-laden gas the thin skin erodes and dust packs the cavity. In genuinely dusty duty it is the wrong blade no matter how good its clean-air number looks.

The curved plate gives up a few points of peak efficiency and takes dust in return — no skin to perforate, no cavity to pack, and it can be made in abrasion-resistant material and hardfaced on its wearing faces.

The flat plate, backward-inclined, is the easiest of all to re-plate or hardface in the field. Choose it when repairability outweighs the last point of efficiency.

Two questions worth asking any supplier: is the quoted aerofoil hollow, and when the blade wears, can it be hardfaced — or is the wheel scrap?

https://jitamitrablowers.com/insights/backward-blade-aerofoil-vs-plate/?utm_source=fb&utm_medium=social&utm_campaign=q4-2026-library

26/08/2026

The site gauge said low pressure. The fan was quiet, cool, smooth and drawing normal current.

That combination is the tell. A fan genuinely failing to make pressure — a reversed impeller, a slipping drive, a stalled aerodynamic condition — almost never fails silently and cleanly with every other parameter normal.

The works test record showed the fan achieving 312 mmWC against a required 305 mmWC at design conditions. The gap was in how the field reading was being taken, not in the machine.

A pressure reading means nothing without three things attached: where it was tapped, what it was tapped with, and under what air conditions it was read. Change any one and the value changes legitimately, with nothing wrong anywhere.

So we fixed the measurement rather than the fan — a corrected field protocol with a transition-piece tapping, a calibrated digital manometer and a tapping-point diagram, plus a written clarification of the test-versus-design figures. A site visit was held in reserve.

Our file holds no record of the customer's re-measurement or sign-off, and we are not claiming a closure we cannot evidence.

https://jitamitrablowers.com/case-studies/combustion-air-low-pressure/?utm_source=fb&utm_medium=social&utm_campaign=q4-2026-library

25/08/2026

Clean air does not make the duty easy.

A cleanroom AHU fan drives filtered air through pre-, fine- and HEPA/ULPA banks to hold the pressure cascade and air-change rate that keep an ISO 14644 / GMP grade A–D space clean. The filter bank imposes 600–1,200 Pa, and the unit runs 8,760 hours a year. A wheel that delivers that static a few points below its achievable efficiency burns money every hour it runs — on a 30 HP AHU fan that is tens of MWh a year, in a facility that never switches off.

The second priority is that the fan must never contaminate the airstream it exists to keep clean. A painted-steel wheel, a crevice that traps and re-releases contamination, a shedding coating — any of them fails the room's classification. So: SS304 or SS316, or cleanable epoxy, smooth-welded and ground, crevice-free, low-leakage casing, IP-rated washdown motor.

And the cascade has to hold — typically +10 to +45 Pa between grades — as filters load from clean to change-out. EC or VFD control holds the set-point without a damper's throttling loss, on a wheel balanced to ISO 21940 G2.5.

https://jitamitrablowers.com/applications/cleanroom-pharma-ahu/?utm_source=fb&utm_medium=social&utm_campaign=q4-2026-library

24/08/2026

A cell-manufacturing line splits into two worlds of air, and a fan that suits one is wrong for the other.

On the clean side, dry-room and cleanroom AHUs move large volumes of ultra-dry, particle-free air held below −40 °C dew point. Any oil migration past a shaft seal, any casing that sheds, any vibration carried into the room, and you have contaminated lithium electrode with the machine that was supposed to protect it.

On the hazardous side, coating and drying give off NMP and solvent vapour — a flammable atmosphere, ATEX Zone 2 — and mixing and calendering release fine electrode and metal-powder dust that is commonly combustible, Zone 22.

So the clean supply gets a high-efficiency aerofoil wheel at its best-efficiency point, sealed bearings out of the airstream, a wash-down casing that does not shed, and balance to ISO 21940 G2.5 or G1.0. The exhaust gets spark-resistant construction to AMCA 99 with a bonded, earthed rotor and bearings outside the gas path.

We have not yet run a named battery reference, so we lead with the engineering rather than a number.

https://jitamitrablowers.com/industries/battery-ev-manufacturing/?utm_source=fb&utm_medium=social&utm_campaign=q4-2026-library

21/08/2026

One car-park exhaust fan does two jobs that want opposite machines.

For thousands of hours a year it dilutes vehicle CO and NO₂ — a low-static, part-speed, quiet duty beside occupied floors and lift lobbies. Then on the worst day it goes to full duty and pulls hot smoke off the deck at the temperature-time class your fire strategy specifies: commonly 250 °C or 300 °C, held for a 1 hour or 2 hour class.

A commodity fan is sized for the ambient case and hopes the fire rating is a sticker. It is not. A fan built for ambient can lose its bearing lubrication, distort its wheel or trip its motor within minutes at 300 °C — exactly when it has to keep holding the escape route.

We size the wheel and select the drive to hold both points, and prove both on the rig. Heat-rated construction sized for thermal growth, motor out of the airstream or rated for the duty, built and in-house tested to run the full class rather than a momentary excursion. Where the project needs certified smoke-fan performance, we route it through a Notified Body under EN 12101-3.

https://jitamitrablowers.com/applications/car-park-basement-exhaust/?utm_source=fb&utm_medium=social&utm_campaign=q4-2026-library

20/08/2026

A fan that ran well and then started to shake is almost never a fan that was built wrong.

It is a fan changed by its transport, its installation, or its process. On a coating line, above all, by its process — the impeller lives in an aerosol of paint, powder or resin, and it deposits unevenly. That condition does not exist on day one. It grows in service, which is exactly why the fan was fine when it went in.

On a 15,500 CMH, 60 mmWC coating-line blower we ruled out the cheap causes first — mounting, hold-down bolts, soft foot, coupling, ducting strain — then balanced it in place, in its own bearings, on its own foundation. A works balance on a bare rotor cannot correct for accumulated process deposit. In-situ balancing can.

One pass. Six measured points, all under 3 mm/s, peak 2.9. ISO 14694 sets fan acceptance at 4.5 mm/s rigidly mounted BV-3 and 6.3 flexibly, so it sits in the unrestricted band on either basis.

What our file does not hold is an as-found figure, so we will not say we took it from X to Y.

https://jitamitrablowers.com/case-studies/coating-line-field-vibration/?utm_source=fb&utm_medium=social&utm_campaign=q4-2026-library

19/08/2026

Most fan makers will only touch their own machines. We repair, refurbish, re-rate and re-part centrifugal fans and blowers regardless of who built them.

Shafts, bearings, impellers, hardfacing and drop-in spares — in our shop or in your plant. Every rotor re-balanced to ISO 21940 before it ships.

That covers the jobs that do not fit a warranty conversation: a coupling machined back to spec on a 2,700 CMH, 1,170 mmWC, 30 HP blower. A hot-air dryer blower needing component replacement and fitment. Oven-circulation blowers where the real question was the bearing root cause, not the bearing. A 27,000 CMH-class machine closed out in a single field visit.

If a fan on your plant is shaking, running a hot bearing, or simply not doing what its nameplate says, we will come and measure it first.

https://jitamitrablowers.com/services/aftermarket-repair/?utm_source=fb&utm_medium=social&utm_campaign=q4-2026-library

18/08/2026

A boiler fails at the interfaces, not at the fans.

It runs on four coordinated fans — ID, FD, PA and SA — and when they are bought separately they do not track each other across load. The ID over-pulls, the FD chases it, the furnace pressure hunts, and the boiler trips on draft. Two vendors, two curves, never matched to hold −5 to −10 mmWC together.

Then there is turndown. A boiler swings from about 40% to 100% MCR. If each fan holds its duty on its own logic, the air/fuel ratio drifts at part-load and the burn goes dirty — smoke, CO, unburnt carbon.

And when something does fail, four vendors means four GA languages, four spares kits, and four suppliers pointing at each other. Nobody owns the island.

We engineer the set as one: ID and FD sized as a coordinated pair off the same firing rate, all four on a common VFD-led control strategy, a shared bearing, seal and coupling family with one L10h ≥ 40,000 h standard, and one QA record for the whole draught-fan island.

https://jitamitrablowers.com/applications/boiler-fan-suite/?utm_source=fb&utm_medium=social&utm_campaign=q4-2026-library