Question about hydraulic calculation of flexible pipes

[UFT12]

This is general question. How do you guys claculate the pressure loss through a flexible pipe supplying a sprinkler? From the manufacturer's data I see one column with the actual pipe length and one with the equivalent based on 1" S40. So assuming I have my piping system made of S40, do I need to simply add these two values or just ignore the actual length and carry only the eq. length into the calcs?

 

[TravisMack]

It is just the same as any fitting. You use the manufacturer's equivalent length.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

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[UFT12]

Thank you.

 

[MatthewJWillis]

Beware. The. Kinks.

Also, Verify if FM is involved as you can see higher values in their column...

R/
Matt

 

[UFT12]

Thank you but this raises an other question, assuming I need to comply with either FM or UL and my branch line is running just above my pendent sprinkler on tiles, so lets assume the flex gets off the branch line on the side, so only one bend is formed on the flexible, do I really need to calculate with the indicated value on the table regardless? I assume yes since I don't see any way how could I adjust this.

 

[MatthewJWillis]

Yes. The number of bends given are maximum.

We may assume just the one in design. The plumbers, hvac, and electrical folks make it quite another in the field..

R/
Matt

 

[TravisMack]

You are way overthinking things. Make sure that you have enough distance that they can get the minimum radius with the bend. Then just use the equivalent feet. You can almost bet certainty, as Matt stated, that the flex will get used in the field to account for things we didn't see or changes that were made.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

"Follow" us at

https://www.facebook.com/pages/MFP-Design-LLC/92218417692