Multiple hole orifice plate 1

[SKeith1]

Sorry, I'm really new to multiple hole orifice plates.

When designing a multiple hole orifice plate, how do you determine the diameter of the holes to the spacing of the holes? Is there a standard I can read?

Thank you for any help.

 

[zdas04]

What are you trying to do with the plate?

The ones we use in gas measurement (to condition the flow upstream of the meter plate) have a very low dP and a very high percentage of dP that is recovered downstream. Those plates were developed to provide a nearly swirl-free stream to an orifice plate--everybody's plate from Dr. Laws to Mr. Galagheger, to the guys in Canada that knocked off everyone else and have dominated the market was developed through experimentation and there was never a closed-form equation to describe why and how they worked.

David

 

[SKeith1]

Yes, I'm looking at a multiple hole orifice plate for gas pipeing. Are there standard multi-hole orifice plates or are they manufactured according to your needs? I understand the basic principal behind them, but I wanted to know more about their design.

 

[zdas04]

What do you want it to do in your gas piping? Are you trying to force a pressure drop, get rid of swirl, or do gas measurement?

David

 

[SKeith1]

Actually, we are trying to reduce low frequency noise.

 

[zdas04]

Could be a very good use of a multiple hole orifice plate. I would start with something like the units from Precision Pipeline Equipment or Canada Pipeline Accessories . The first one has several plates specifically designed for noise reduction.

David

 

[dcasto]

the rule of thumb for a low frequency "pulsation" damping is a 200" H2O differential through the orifice. A multi hole plate can have its differential pressure estimated by just using area of the holes combined.

If you calculate you need a 5 inch orifice in a 12" line, then 5 1" holes will give the same differential pressure.
In any case, it takes some experimenting unless you want to pay the big money for an accoustical study.

Another system used is to build a bottle that has a diameter of 6 to 10 times the diameter of the pipe it is on. Its lenght would be 3 to 5 times the diameter. There would be a solid circular plate the diveds the vessel in half. The line would go into the vessel that is alined horizontally, at the center of the head. The line would exit the chamber and jump over to the other side. The gas would exit the other side through a line in the center of the head. In the line that connects the two chambers, an set of flanges to hold the orifice plate would be installed.

I'm not the designer of them, but what little I know of accustics is that this system is effectively a low pass filter with a capcitor, and resistor and another capcitor.

 

[Scotsinst]

Approximately; if you calculate you need a 5" diameter orifice then you will need 25 1" orifices to achieve the same differential pressure.