Enter the diameter of the nozzle and the number of nozzles into the calculator to determine the total flow area.

TFA Forumla

The following formula is used to calculate a total flow area of a downhill drilling tool.

TFA = (pi * D^2) / 4 * N

  • Where TFA is the total flow area
  • D is the diameter of the nozzles
  • N is the number of nozzles per tool

Often times for downhole drilling tools, the nozzles are expressed in 32-inch increments, i.e. 10/32. In this scenario, the formula can be simplified to:

TFA = N^2 / 1303.8

  • Where N is the numerical value out of 32, so N =10 in the example above

TFA Definition

What is TFA?

TFA stands for total flow area. It’s a term used to describe the total area of an opening on a device that fluid is designed to flow through. This is a common term in downhole drilling tools but can also be applied to any nozzle.

Example Problem

How to calculate TFA?

First, determine the diameter of the nozzle. For this example, the diameter of the nozzle is found to be .45 inches.

Next, determine the number of nozzles per tool. In this case, there are a standard 3 nozzles per tool.

Finally, calculate the TFA using the formula above:

TFA = (pi * D^2) / 4 * N

TFA = (3.14159 * .45^2) / 4 * 3

TFA = .4771 in^2