Fluid Velocity in a Pipe?

My mate Herr B has always been very helpful.

Not unless you know the flow-rate. Diameter alone is insufficient.

can some1 help with regards to minimum, operational and maximum flow thru a pipe of given size.

There are guide lines for the velocity of different fluids through the pipelines.

eg for water it is taken as 5m/s and upto 10 times (around 50m/s) for gases that may include steams too.

Note:

1. There is no minimum flow restriction. A pipe line may always have a no flow condition.

2. However too low a flow may cause accumulation of debris/solids in the pipe line. Usual recommendation is 1/5th of the maximum flow ie usually >1m/s for liquids.

3. the restriction is usually in the maximum flow.

4. The maximum flows are a bit empirical, but the safe one. The actual calculation will be a bit rigorous, you have to take care of the fluid properties, the pipe material, its surface roughness and texture and so on.

friction between fluids and pipes increases exponentially with the velocity,

Really? I thought it was a square law.

Perhaps the exponent is 0.5.

Those are process engineering questions. If you are not the process engineer, then you need to find the process engineer for the unit you are working with and ask them for the information. Or at least ask an operator.

If you are the process engineer or if you have been tasked with finding those flows, then you need to look at the whole system to find it.

Operating flow will be based on unit needs. Someone that is familiar with the process needs through a particular pipeline can give you that.

Minimum flow can be as low as 0 but I'm guessing you need minimum operating flow. Again, the unit should tell you what their minimum needs are to operate.

The maximum flow will be set by the equipment. For instance, you may have a pump in the line that determines the flow rate, so the max flow rate of the pump will give you the maximum flow for your pipe. This again can be calculated with by doing a full system design but you won't find it by just looking at one pipe.

flow: 21000 Nm3/hr

temp:100 deg C

Pressure: 0.62 Mpa

fluid: gaseous air

compressor outlet is DN 250 .. but the connecting static equipment has an inlet nozzle size of DN400.

so basically the noob designer is using a reducer of DN 250xDN400 to connect the 2 equipment.

so can u expalin the basis of design. or is it that just the nozzle size of the static equioment id DN400, the designer is using a reducer in b/w to connect the 2 equipments.

Are these 2 pieces of equipment so close to each other that all you can fit is a reducer?

It's hard to tell from your description but it sounds like both pieces of equipment are new to your facility. Or you're purchasing both pieces of equipment. If that's the case, you might be able to talk with the equipment manufacturer to change the nozzle sizes. Be careful though because this can cause damage to the equipment as in the case of pumps.

The designer usually just works with what he is given on pieces of equipment. If the project manager/engineer tells a designer that he is buying a pump with DN400 inlet nozzle then that's what the designer works with.

Mean velocity equals volumetric flowrate divided by cross-sectional area.

Dear prashantsah

The answer is YES, provided you furnish the QUANTITY of FLOW, PIPE SIZE etc.

DHAYANANDHAN.S