Cooling Tower Glossary

Fan stack

Shell

Velocity-recovery stack. The bell-mouth inlet turns the air into the fan without separation, and the flared exit converts discharge velocity back into static pressure — a surprising share of fan energy is won or lost in this profile alone.

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Fan blade

Drive train

Axial fan, 4–6 blades, from roughly 2.5 to 40 ft in diameter depending on cell size. Blade pitch is the primary airflow adjustment, and low-noise profiles exist where a site needs them.

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Gearbox

Drive train

Right-angle bevel gearbox. Turns the horizontal drive into the vertical fan shaft. Oil level, backlash and bearing wear are the routine inspection points.

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Motor

Drive train

Totally-enclosed fan-cooled motor on the deck, outside the fan stack and clear of the wet discharge. Its own cowl fan cools it, so blocked vents and a hot terminal box are what to look for.

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Drive shaft

Drive train

Composite tube with flanged couplings and flexible elements at each end, carrying torque from the external motor to the gearbox. Misalignment shows up here first, as vibration.

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Drift eliminator

Fill & media

Blade or cellular type. Strips entrained droplets from the leaving air — the difference between plume, water loss, and deposits on nearby plant.

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Distribution system

Water distribution

Hot water arrives from the process through the main, rises into the header, and spreads across the plan through the laterals. Even flow to every nozzle is what a performance test is really measuring — a blocked lateral shows up as a hot corner.

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Spray nozzle

Water distribution

Fixed-orifice or swirl-vane nozzles on the distribution header. Uniform coverage over the fill is what performance testing actually measures.

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Fill pack

Fill & media

Film or splash fill, in several flute geometries chosen for water quality. The largest single lever on thermal performance — and the first thing to foul, sag or collapse.

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Air inlet

Airflow

The open face the fan draws through. Air enters here, crosses the falling water in the fill, and leaves through the stack as a warm saturated plume — induced draft. Anything that blocks the inlet, or lets discharge recirculate back into it, costs capacity directly.

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Cold water basin

Shell

Collects cooled water and feeds the return line. Silt, scale and corrosion here quietly degrade everything downstream.

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