gas pipe velocities, erosion and sound pressure level

[pecan204]

Hello,

I have a gas pipe orifice metering tube that measures 6 in OD schedule 40. I am review the orifice size and resulting piping velocities.

Does anyone know any velocity limits?

I calculate velocities at the orifice around 163 Ft/sec. 60 Ft/Sec in the pipe.

Does anyone have a correlation on what sound pressure level that might produce?

Are there limits for erosion?

Thanks
Ken

 

[TD2K]

You don't have a problem with erosion by gas flow itself unless there are liquids or solids in the gas stream. Typically, you don't want to go much over 120 ft/sec in a gas stream simply due to pressure losses. In addition, I've seen 80 ft/sec suggested as the point where you start to get noise created.

The velocity in your main line at 60 ft/sec seems quite reasonable strictly on a velocity criteria. The velocity through the orifice suggests a beta ratio of about 0.6, is that in the ballpark? There's always a velocity increase of course going through an orifice plate due to the reduction in area for flow but nothing about this setup with the information you've given jumps out at me.

What are the operating conditions? Sorry, I don't usually get involved in estimating sound levels so I can't help you there.

 

[pecan204]

The operating conditions are about 380 psig static pressure at 60 to 80 F.

That was a beta ratio of 0.6.

Thanks for the comment.

 

[BigInch]

Don't worry about the sound. You're not making any.

Going the Big Inch!

http://virtualpipeline.spaces.msn.com

 

[BigInch]

OK, I calculated some ranges and it could be borderline, depending on dP. I take it this gas is CH4.

Hope you like this one,

dBA = 10 * log(Q^2 *(dP/P1)^3.6 * (T/Mw)^1.2) + 126

Q kg/s
dP kPa
P1 upstream p kPa
T ºK
Mw Molecular Wt



Going the Big Inch!

http://virtualpipeline.spaces.msn.com