Select pipes

Owned by Dennis De Beuckeleer
Last updated: Apr 25, 2023 by Jeroen Belet
5 min read

After the action "Compute design flows" you go to the next step "Select pipes"

“Select pipes” button in Hysopt

In the figure below, an example of the Hysopt pipe selection for steel pipes is shown. The selected pipe diameter and the corresponding pipe length is given in meter. The total pipe length is shown in the right top corner. The user can manually override the Hysopt pipe selection. In the example below, the DN 80 pipe selection was manually changed to DN 100 pipes.

Hysopt pipe selection - Output example

Pipe types

Following standard pipe types are available in the Hysopt software.

Normal pipes

  • Steel pipes (welded): NBN EN 10255

  • Steel pipes (precision): NBN EN 10305-1 and NBN 10305-2

  • Copper pipes: NBN EN 1057

  • Multilayer: NBN EN ISO 21003-2

  • Epoxy

  • HDPE 100 SDR 11

Heat network pipes

  • External steel pipes : CIBSE CP1

  • External PEX pipes : CIBSE CP1

You can change the pipe type when selecting a pipe on the canvas.
You can add custom pipe types if desired via the

Standards for pipe sizing

For the moment, Hysopt supports three standards for pipe sizing

You can select the desired standard via the

You can also choose to deviate from the standards, and create your own custom pressure profile, as explained in

ISSO

The ISSO standard allows three types of selection criteria:

  • Constant speed (constante snelheid)

  • Constant friction or constant pressure drop (constante wrijving)

  • Gradual speed reduction (geleidelijke snelheidsreductie)

If you select the ISSO standard, by default the method of gradual speed reduction is used.
By default the tipping points are used as defined in the standard (see the red circles in the screenshot below).

It’s important to know that the ISSO standard allows you to deviate, and change the method, or change the default values, and you are free to modify the values for these tipping points according to your experience or according to the situation. You are also free to introduce extra tipping points and add an extra switch between constant speed and constant friction.

See the paragraph on how to make these kind of custom modifications.

CIBSE CP1 Heat networks: Code of Practice for the UK (2020)

The CIBSE CP1 (2020) guide is widely used and recognized in the UK for sizing heat network pipework.

At this moment, the Hysopt software only supports pipe sizing based on maximum velocity, maximum pressure drop per meter, or target pressure drop per meter. However, CIBSE CP1 recommends pipe sizing based on typical (or target) velocity.

The typical velocity table that can be found is CIBSE CP1 (2020) is also commonly applied for pipe sizing inside buildings. Therefore, the typical velocity table is used for the pipes that are defined as ‘normal pipes’. Here, the typical velocities are used as a maximum velocity constraint to select the right pipe size.

For the ‘heat network pipes’, a similar table is used but the typical velocities are increased with 30% to obtain a maximum velocity to select pipes for heat network purposes.

Both tables are made available below.

It’s important to know that the CIBSE CP1 profiles for ‘heat network pipes’ are also used when ISSO and WTCB pipe selection mode is applied. The CIBSE CP1 selection criterium was also used for ISSO and WTCB heat network pipes because those two latter standards do not specify pipe selection methods specifically for heat networks.

The two ‘heat network pipes’ are (see image below):

  • Steel pipe (district heating)

  • PEX (district heating)

Pressure profile CIBSE CP1 (2020)

A. Table with typical velocities from CIBSE CP1 (2020) → used for ‘normal pipes’

B. Table with 30% higher allowed maximum velocities → used for ‘heat network pipes’

Custom pressure profiles

If you like, you can create your own pressure profiles and implement your own practice / standard.
The Hysopt software supports 3 methods for pipe sizing:

  • Maximum velocity

  • Maximum pressure drop per meter

  • Target pressure drop per meter

Both velocity and pressure loss serve as 'hard' filtering criteria. Pipe diameter is never selected when the pressure loss is larger than the maximum, or the velocity is larger than the maximum velocity. When target pressure losses are supplied, the pipe diameter is selected from the set of diameters that are allowed (by the above criteria), and which has the smallest deviation from the target pressure loss. Summarized this means: that when both are supplied the most restrictive is applied and a "0" value is ignored.

You can change the pressure profiles via the

Pipe settings

The user can change the pipe types and the pipe selection profile by first clicking on the button in the top right corner of the screen stating "model settings".

A popup window will appear where the user can change different design options including the pipe types and pressure profiles. The user can add or modify the pipe types and the pressure profiles by exporting the excel sheets, changing them, and importing them again. This way, any standard or best practice for pipe selection and/or pipe physical properties can be implemented and applied in our software.

Be aware that if you add new pipe types, that you also need to modify the correlated pressure profiles. Both excel files need to be consistent. The software will show a warning if you try to upload pipe types & pressure profiles that are not compatible.