Reducer right?

sorry guys

wrong community

my bad

Yes, a reducer would increse the velocity. Flow rate constant, area decreases hence velocity increases [Q = A*V]

Yes, a reducer would increse the velocity. Flow rate constant, area decreases hence velocity increases [Q = A*V]

But take care of the pressure loss, if that is not an issue,reducer is good.

but a good engg practice is to size the pipe to meet the velocity of 1- 5 m/s

Yes, use reducers, though one needs to take into account any requirements imposed by the manufacturer in terms of the minimum diameters of straight pipe both upstream and downstream of the sending element. These requirements are to establish an even velocity profile across the pipe and are usually important in deciding the best pipe/location arrangements for flowmeters.

In large diameter pipes it is also necessary to make sure the pipe is full.

So if all else fails, read the instructions!

Is that how you selected your flowmeter?

When we select flowmeters, we specify the nominal flow rate that is expected to flow through the tube and then select the size of the flowmeter that would satisfy the requirement.

Using this method, we never had problems with getting the minimum flow velocity through the tube. Occasionally, the flow tube would be smaller than our pipe which made a reducer necessary.

Keep in mind also that vortex flowmeters need several pipe diameters of straight pipe run after the reducer to minimize the turbulence created by the reducer. The manual will tell you how much. The ones we used specified 15 pipe diameters for reducers, 30 if you have elbows before the flowtube.

Yes, using a reducer will increase the velocity with a pressure drop (ΔP must be calculated and studying its effects on total pressure and flow rate) . But you have to check with the supplier instructions if there is a limitations or not on upstream and down stream pipe lengths, with respect to the location of your flowmeter.

Flowmeters Vortex:

Regardless of the numbers of shedder bars, all vortex flowmeters utilize the same basic design. As fluid moves around the shedder bars, vortices form and move downstream. The frequency of the vortices is directly proportional to flow rate. Vortices cause pressure fluctuations which are sensed, amplified, and converted to a 4 to 20 mA output.

To maintain system accuracy, a Reynolds number > 10,000 is needed.

To calculate, use the following formula: Reynolds number = DV/v

D=internal pipe diameter (m)

V=flow velocity (m/s)

v=Kinematic viscosity (m²/s) ♦ Water (v)=1*10^-6m²/s

You need to put reducers to obtain the flow rate of 1.5 meters/sec. These should be eccentric reducers with the flat side on top to avoid air entrapment in the reducers and resultant turbulence. The counter flanges of the flow meter (i.e. flanges welded to piping and bolted to the flow meter) should be ground inside at the weld joints if required to obtain a smooth surface without any excess penetration of weld metal to avoid turbulence.

The normally used minimum straight length of pipes upstream and downstream of the flow meter are 20 times and 10 times respectively of the Nominal dia of pipes. However the manufacturer's recommendations should be observed.