Orifice and Head

[wookiyo]

I heard someone can adjust the lower head exactly under same capacity for using an orifice.
I know the principal of orifice using the differential pressure but how to get the pressure drop to the setting value.
Let me know the "formula" or necessary "web information" to refer.

Thank you for your help.

 

[TD2K]

I'm not sure what you are asking by "pressure drop to the setting value". You size the orifice for the flow in the system and the pressure drop between the high pressure and the low pressure sides of the orifice.

The low pressure value is simply the pressure you want. Crane's technical paper 410 has the equations for the pressure drop across an orifice.

 

[wookiyo]

Thanks for your kind answer. but i'm afraid that don't have a crane's technical paper.
i know what you mean, but actual, detail actions that intend to adjust to the requied lower head are needed to me.
I thnink the low pressure value at discharge of orfice you said is the interstage action whick i wanna know.
If the lower head is assumed that is required to the value for the system, how to get the value the low pressure value at discharge of orifice.
And If the low pressure value is given, what sort of orifice are need?

Thanks in advance.

 

[devaxrayz]

Your question is not really clear, but i figure this maybe can answer.

Orifice Pressure Drop is P1 - P2, where P1 = pressure inlet orifice and P2 is pressure discharge of the orifice.

You need low head at a point downstream the orifice right?? So P2 should be head you required at that point plus piping head loss from discharge orifice to your point at the capacity (flow) you choose.

P1 should be the discharge pressure of your pump (if using pump) at capacity you use (see pump curve) minus piping head loss from pump to inlet orifice.

Now u have got orifice DP and flow (capacity). If u want to lower the head i assume u are sizing an orifice. If u sizing the orifice, one of the output is bore diameter. Orifice equation can be find in Perry Chemical Eng Handbook or any fluid mechanics book.
U can use this equation for calculating bore diameter when sizing orifice or calculate pressure drop at existing orifice or else.

Hope can help

-Rayz-

 

[wookiyo]

THANKS it was a good advice to me.