Orifice placement in air delivery system

[dbecker]

Hello,

I am a designing a piping system that branches off in a few locations.

I am using a 1D flow system software. There are flow rate requirements for the different branches in this system. The overall system flow rate is given to me and the flow rate requirement of each branch.

I first place a flow source and set it to my required flow. I build the system using all the components I need, pipes, elbows valves etc.. That is fine.

I iterate on different pipe sizes and go back to my flow source and query it in the results file to try and match the junction pressure at the source to the real pressure that I am trying to match in the system.

So far this has worked very well and the system is accurate. I noticed one problem though, the flow rate I am using is rather high and I do not want to pass mach 0.25 for airflow.

If I use pipe that is too big, my source pressure which falls out of the flow source will be very low (as expected). If I use a main pipe that is too small, I will get the correct source pressure at my flow source but the pipe velocities will be screamign because the pipe is undersized.

I would like to use an orifice restrictor. Should I put this orifice restrictor directly at the flow source which will then impact the entire system and be easier to manage? Or, put multiple flow orifices everywhere and try to balance it out that way?

I prefer to use one flow orifice at the flow source because it will take all the guesswork, if this is 'OK' in industrial practice please advise me. If not, please advise why not.

Thank you

 

[BigInch]

It would seem that your velocities are too high for "industrial" systems. Mach 0.25 is well above "industrial" pipe velocities. Your system is probably not considered "process" piping and a very special and very specific design is needed. Hope it works. Trying to control flow using just orifice plates isn't easy.

 

[dbecker]

Well what is an acceptable velocity for "industrial" piping? And what is the best way to control it if not orifice plates?

 

[mbt22]

dbecker,

What is the system for? What are the branches delivering to? I'm just wondering whether the flow rates required to each branch are what the system on the end will pull, in which case no orifices or restrictions required, or are you trying to push a known flow down each branch?

Regards,

Matt

 

[dbecker]

hello mbt22,

I have the system modeled in a 1D system software, the flow rates are all tuned to deliver the correct amount of air, as it sits. I am using flow orifices to control flow in each branch.

Instead of using multiple orifices I want to control flow using a single orifice at the flow source (that is set) and then just size my pipe accordingly to get the pressure drop in each branch which will dictate flow.

The system is delivering air, I can't say what it is for. Just that there is a set air supply flow rate requirement at some pressure, and to control the flow rate I would like to use an orifice at the source. (Flow rate is set)

Thanks