Parts of a Cooling Tower – Fill, Fan, Drift Eliminators

All 19 parts on the diagram

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Air side 7

Fan It pulls air through the tower and blows it out the top.
Fan guard A wire cover over the fan.
Fan motor It drives the fan.
Louvers Slats across the air inlet that keep splashing water in.
Plenum The open space the air crosses between fill and fan.
Drift eliminators They catch water droplets before the air carries them out.
Casing The outer walls of the tower.

Water side 6

Inlet connection Warm water arrives at the top of the tower here.
Hot water basin Also called the distribution basin; warm water is piped into it.
Nozzles Holes in the basin floor that spread water over the fill.
Cold water basin Also called the collection basin; the cooled water gathers here.
Fill Sheets that spread the water out so more air touches it.
Spray nozzles They spray the warm water down over the fill.

Basin fittings 6

Float valve (make-up valve) It lets in fresh make-up water when the level drops.
Overflow Water above the set level runs out through it.
Outlet Cooled water leaves the tower here, drawn off by a pump.
Drain Opened to empty the basin and wash out dirt.
Strainer A screen that keeps debris out of the outlet pipe.
Sump The low part of the basin that the outlet draws from.

How this list was compiled: Every name checked on 2026-09-30, a name kept only where two independent sources use it. Wikipedia, Cooling tower (https://en.wikipedia.org/wiki/Cooling_tower); US Navy, Utilitiesman 2, training manual NAVEDTRA 10662 (1990), chapter 14, Cooling Towers (https://archive.org/details/utilitiesmanii024855mbp); and the user manuals of three unrelated cooling tower makers, read as archive.org full text for their part names only: a crossflow tower (https://archive.org/details/manualzilla-id-5810543), a round counterflow tower (https://archive.org/details/manualzilla-id-6038448) and a plastic counterflow tower (https://archive.org/details/manualsbase-id-638330). Licence: own work

The drawing: Drawn for this site on 2026-09-30 from plain geometry; a schematic of no maker's product, nothing traced. Licence: own work

How it works

A cooling tower cools water by letting some of it evaporate into moving air. The first drawing cuts through a crossflow tower, where the air moves sideways through falling water. The second cuts through a counterflow tower, where the air rises against the spray.

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Crossflow: air from the sides

Warm water arrives at the inlet connections and fills the hot water basins. It drips through the nozzles and runs down the fill. The fan pulls air in through the louvers and across the fill. Drift eliminators catch the droplets, and the air crosses the plenum and leaves at the top. Cooled water gathers in the cold water basin.

Counterflow: air from below

Spray nozzles wet the fill from above while air rises through it. In the basin, a float valve adds make-up water, an overflow sets the top level, and a strainer covers the sump, where the outlet is.

Questions and answers

What are the main parts of a cooling tower?

A fan, fill, a way of spreading the water (a hot water basin with nozzles, or spray nozzles), louvers at the air inlet, drift eliminators, a casing, and a cold water basin with its float valve, overflow, drain and outlet.

What is the fill in a cooling tower?

The material the water falls through. It spreads the water out so more of it meets the air for longer. Film fill is thin sheets that the water runs down; splash fill breaks the falling water into drops.

What do drift eliminators do?

Drift is the water droplets carried out of the tower with the air. Drift eliminators make the air change direction several times, so the droplets are caught and stay in the tower.

What is the difference between a crossflow and a counterflow cooling tower?

In a crossflow tower the air moves sideways through the falling water, which gravity spreads from a hot water basin. In a counterflow tower the air moves straight up against the water, which is sprayed from nozzles under pressure.