Effects of Expanding HDPE PN10 Pipe Size Mid Line 1

[mahara7a]

Hi guys. I'm wondering if this kind of installation will possess issues/ effects in the future. I have a pipe from pump run below structure 160mm OD PN10 (HDPE) that has already been installed after some time. Based on the drawing, it will be connected to a pipe serving an area that is sized at 180mm OD PN10 (HDPE). My concern is, doesn't that with that size expansion fitting it will cause head loss? Wouldn't it be better to just use 160mm OD along the way instead of expanding it. In my opinion, there is no advantage of expanding it to 180mm as the origin size from the pump is already 160mm. I'm a junior engineer for a contractor btw.

Thanks in advance.

 

[LittleInch]

Just do the sums.

The head loss across a 160 x 180 reducer is v small.

Head loss difference between 160 and 180 can be substantial depending on flow rate and lengths.

It is something around (D1/D2)^4.

This calculation is very easy to find online.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[HTURKAK]

Compare both cases . Calculate the pressure drop and decide accordingly if it is worth to increase the diameter or not.

https://www.hydraulic-calculation.com/article.php?ID=1

https://www.krah.net/en/news/latest-news/276-hydraulic-calculation-of-pe-pressure-pipes

Use it up, wear it out;
Make it do, or do without.

NEW ENGLAND MAXIM

 

[mahara7a]

Thanks Littleinch and Hturkak for the replies. Mathematically the total head loss for 180mm pipe is for sure lower compared to the one that is 160mm. My another concern is, i believe it is not a common practice where pipe from a pump at mid line got increase in size (correct me if im wrong). I cant understand the reason behind it. The best is of course if the pipe from the pump is 180mm up to its distribution points. In short, i have never seen pipeline installed in a manner where fluid flow from smaller to bigger diameter pipe. Ive seen it in gas pipeline but never seen it for water pipeline (correct me if im wrong again).

 

[LittleInch]

You're wrong.

There's not enough information to know why this is the way it is.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[mahara7a]

Thanks for correcting me. I agreed. This issue started with less information known in the first place. Perhaps i will have further discussion with the designer for their point of view.

 

[LittleInch]

For any reasonable length of pipe, you normally go up one or two pipe sizes compared to pump outlet size.

Optimum / most economic velocity in your pipe is around 2m/sec. Pump exit velocity is often >3m/ sec.

Higher velocities for shorter lines, lower for longer ones.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.