Range and Approach: the two spans that set a cooling tower's duty
The three temperatures of one example, and the two spans between them.
Tower Lab
Every chart from the cooling tower guides, one page each, with a shared conditions bar and cited formulas.
Every chart in the cooling-tower guides has its own page here, each one adjustable. Set the site conditions you work to and the charts read the same plant, so a figure you compute on one page matches the one somebody else gets from the same guide.
An engineering reference, not a rating tool. These charts evaluate published relations at illustrative numbers. They are not a measurement, not a rating of any cooling tower, and not a service or a quotation — no chart on this page reports the performance of a real installation, and none of them replaces a test. Each family links the guide that explains it, as that guide publishes.
Thermal rating
What the tower does with the heat and the air it is given.
The Merkel demand curve: the driving force the fill integrates
hs(Tw) against the operating line, with the driving force between them.
Merkel number and the entering-air convention that shifts it
Two entering-air conventions, and what the offset costs in fill.
Tower capability: where the demand curve meets the characteristic
Demand against characteristic: the crossing capability comes from.
Performance curves: reading a test back to water flow
One curve per wet bulb, and the inverse solve from a measured Tc.
Fill characteristic: KaV/L on log-log axes, and what depth costs
KaV/L = C (L/G)^m, and depth as an additive offset in decades.
Air side
What moves the air through the tower, and what the air carries out of it.
Crossflow against counterflow: the same fill, two arrangements
The same fill in both arrangements, and the fill a crossflow needs.
Drift eliminator trade-off: drift against pressure drop
Drift against pressure drop, priced per eliminator class.
Fan and system curves: the operating point, and the cube law
Where the fan curve crosses the system curve, and the power there.
Water side
What the water balance costs, and what the fill does with the water it is given.
Measurement
How far the number can be trusted once it is read off an instrument.