# How to calculate water pressure drop in cooling tower piping system?

• HVAC Master
In summary, calculating water pressure drop in a cooling tower piping system involves determining the total head loss caused by friction, elevation changes, and fittings. This can be done using the Darcy-Weisbach equation or the Hazen-Williams equation. Additionally, the velocity, flow rate, and pipe diameter must be known. The pressure drop can then be calculated and used to determine the appropriate pump size and operating conditions for the system. Regular monitoring and maintenance of the system is necessary to ensure efficient and effective cooling tower operation.
HVAC Master
TL;DR Summary
calculating water pressure drop in cooling tower piping system
When calculating water pressure drop in chilled water pipisystem (closed circuit) we always use Hazen Williams equation as follow:-
h100ft = 0.2083 x (100 / c)^1.852 x q^1.852 / dh^4.8655
where

h100ft = friction head loss in feet of water per 100 feet of pipe (ft.w/100 ft pipe)
c = Hazen-Williams roughness constant

q = volume flow (gal/min)
dh = inside hydraulic diameter (inches)
but in case of calculating water pressure drop in cooling tower piping system (open circuit), shall we modify something in Hazen Williams equation or shall we use another equation?

https://www.engproguides.com/condenser-water-pump-design.html

Pump intake conditions are atmospheric pressure plus water column (consider pump NPSH to avoid cavitation).
At the end of the hydraulic circuit, you have the sprayers discharging at atmospheric pressure.
Consider also changes of temperature of the water through the pipes circuit.

## 1. How is water pressure drop calculated in a cooling tower piping system?

Water pressure drop in a cooling tower piping system is calculated using the Darcy-Weisbach equation, which takes into account factors such as pipe diameter, length, flow rate, and fluid properties.

## 2. What is the formula for calculating water pressure drop?

The Darcy-Weisbach equation for calculating water pressure drop is: ∆P = f (L/D) (ρV²/2), where ∆P is the pressure drop, f is the friction factor, L is the pipe length, D is the pipe diameter, ρ is the fluid density, and V is the flow velocity.

## 3. How does pipe diameter affect water pressure drop?

The larger the pipe diameter, the lower the water pressure drop will be. This is because larger pipes have a higher cross-sectional area, allowing for a greater volume of water to flow through with less resistance.

## 4. What are some common factors that can affect water pressure drop in a cooling tower piping system?

Some common factors that can affect water pressure drop include pipe length, pipe diameter, flow rate, fluid properties (such as viscosity and density), and the presence of any obstructions or changes in direction in the piping system.

## 5. Can water pressure drop be reduced in a cooling tower piping system?

Yes, there are several ways to reduce water pressure drop in a cooling tower piping system. These include using larger pipe diameters, minimizing the length of the piping system, reducing flow rate, and using smoother pipes with less resistance. Additionally, regular maintenance and cleaning of the piping system can help to prevent obstructions and reduce pressure drop.

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