Drain&Instrument Connections in the Straight Pipe Run of Check Valves 2

[ripaldee]

We have drain (normally closed) and pressure instrument connections in the straight pipe run upstream and downstream of check valves. Do these fittings (ex. weldolets, reducing tees) cause turbulent flow? What mathematical formula will prove the configuration is turbulence-free?

Regards,

 

[racookpe1978]

What diameter is your pipe?
What flow rate of what fluid at what temperature and what pressure?

It is almost impossible to get laminar flow in a pipe with any obstruction at any substantial flow speeds - and you have a check valve and its convoluted, twisting valve body right in the middle of your pipe! ...

Why do you think you have laminar flow in the first place: without ever looking at the small instrument and drain taps in the side of the pipe?

 

[ripaldee]

Case 1: 4" dia. x 100 US gpm x 155 F x 15 psig x oily water

Case 2: 18” dia. x 11,666 US gpm x 155 F x 259 psig x raw water

The straight pipe run upstream (ex. 5D) and downstream (ex. 2D) of check valves is required to make sure that there are no sudden cross-sectional changes (by tees, elbows, reducers, control valves, etc.) within these zones. However, I could not find any piping literature that prohibits the installation of branch connections such as vent, drain and instrument connections in the mentioned straight run. I suppose these branch connections are not significant contributing factors to turbulent flow due to their “no flow” conditions but I want to be sure.

 

[BigInch]

That's to keep large vorticies away from the flapper, not to make laminar flow.

Only put off until tomorrow what you are willing to die having left undone. - Pablo Picasso

 

[ripaldee]

That info (about vorticity) put my research in the right track. But I still haven't found what I'm looking for.

 

[racookpe1978]

A small-diameter pipe that carries no flow tapped into the bottom of a larger, completely full pipe of fluid will not contribute to turbulence inside the larger pipe.

If the physical tap itself extends up past the wall towards the centerline the larger pipe, that extension will cause turbulence around the penetration. A good quality connection has rounded walls where it penetrates the larger pipe, and no protuberance into the main pipe's fluid stream.