DESIGN OF ORIFICE METER

Hello justiger,

do you want a converter, or do you want a plate to put in-line of the flow to slow the flow down to ~90 Lbs psi?

What is the liquid? Just water? Where is the flow from and what will happen to the part of the flow you stop moving through the pipe? Can you tell me is this flow from a high source or from a pump, in which case you may want to adjust the pump speed/pressure?

Take care..................

actually i need a plate to put in line of the flow to slow it down.

The liquid is water,after slowing it down,it goes into a Flume.

the flow is from a 13 stage horizontal centrifugal pump,having a flow of 85 m^3/hr

the pump speed is 4524rmp.

the motor works at 850 KW.

the orifice assemblies must be of flanged ends,one set of mating flanges and hardened ss internals suitable for 250 bar operation as per the pump characteristics.

the flow rate throught the orifice meter must be 24.5 m^3/hr

Any more details required ?

thanks a lot for the reply guys

take care

Har! So, what you are attempting is METERING (as in:- controlling) the flow through a nozzle which has nothing to do with a flow METER? Also, if the nozzle is open into the flume, you wouldn't be worried about pressure on the nozzle side?

Both of the above are assumptions, are they correct?

Sorry, don't understand.

If you want only 30% water, why are you generating 85m³/h why not just 25m³/h ?

Is it worth using so much energy in pumping, just to pump it back ?

For this purpose, some normal orifice is enough with closed pipe to expand the flow, with sufficient length to streamline, and that should take care of your reduced velocity.

yep 30% into the flume and 70% for churnning......

the pump is used for descaling in hot rolling mills

Hi justiger

Yep, we need to know more!

Is it a GAS or a LIQUID that you intend to reduce the pressure of?

You do need to realise that there will need to be a known flow to achieve acurate results. If there is no flow, there will be equal pressure both sides of the orifice!

So, we need to know the flow rate too!

IF it will be a liquid and you have a large orifice and a large flow, you will get a large amount of heat from the pressure drop!

There is a lot to think about here and it would seem vital for you to impart the intended application!

Good luck!

Orifice Meter -from its name- is a system (composed from an orifice plate and orifice flanges which connected to an instrument) used to measure the flowrate through a piping system, and not designed to have the function of a Regulator.

given the deifferential pressure, you'd better of doing that with two or three regulators: with the last one in the regulation loops and the others as self adjusting pressure reducing valves.

If you were thinking of restrictions orifices, the feasability will depend on the type of flow (gaz, liquid) and your pipe diameter.

What I make out is you are looking for a pressure controller. Why do you want to design it ? there are plenty control valves available in market who can do this job for you (ie supply the required pressure control valve) check in the globalspec home page for the control valve suppliers.

A normal orifice will work as flow restrictor and it will reduce the pressure down stream but the reduction will be dependant on the flow and not a constant pressure in outlet (unless the flow, viscosity etc) are all constant. And in case of normal hydraulic fluid, the viscosity is bound to change as the temperature changes and you may land up in an unexpected pressure at downstream despite the design may be OK for a certain parameter.

Hi justiger:

You have several helpful replies.

Can we expect a reply from you anytime soon?

If you ask a question, you should at least follow it up.

I am sort of old fashioned that way. I figure it is common courtesy to reply to a thread I started! OK?

Take care....................

You have not mentioned fluid composition, viscosity, etc. only under non-varible pressure and flow conditions can even an assumtion be made as to the orifice size. Example if the outlet flow is blocked for any reason the outlet pressure will equal the inlet pressure. At In=220 bar, out =6bar problems are anticipated. If you are dealing with gas pressures (as oppossed to hydraulic (Fluid) pressure) a "good" pressure regulator can be used but at such a great differential pressure any change in flow at the outlet may effect the outlet pressure. Good luck. MIKE L.