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Monday, January 29, 2024

How important is the estimation of minor head loss in transport of fluids

 It depends on several factors. In some cases minor head losses may be too small to waste time in its calculations but in some other it may not.

A discussion and some guidlines can be given about this matter.

Two pipe design cases

Head loss $h_L$, head added $h_A$ and head removed $h_R$ are adjustments to the Bernoulli equation so that these only make sense when the piping components are such that need to be taken into account. For example,

  • when control valves are present in a pipe or branch,
  • when the piping design is a network,
  • when pumps or turbines are part of the pipe,
  • among other cases,
heads need to be calculated for a proper balance. Head losses could be of the order of two digits.

However, if the pipe is not too long or intricated then heads could be expected to be small. In this case, head loss could be of the order of one digit.

Factors incresing/decreasing the head loss $h_L$

Head losses may be increased by some factors. Here are some:
  • large pipe sections,
  • pipe length to diameter ratio larger than three digits,
  • pipe accesories such as: elbows, high pressure drop valves, invasive flow meters (orifice plate, venturi meter, etc.),
  • pipe elevations.

Warning

You should always estimate head losses to give a reliable result and reasonable design. However, rough estimations discarding some head losses could only be possible in early design stages to have a quick idea of the overall piping.

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