Flow Through A Pipe

Depends...

How long is the pipe? Is there a load on the outlet? Is it Uphill?

Watt was the engine drivers name.

The pipe is horizontal and consider there is no load at outlet and length is 10 feet.

Right...there's now probably enough info for an answer!

Unfortunately I don't have it...but my gut feel is 'yes' or 'If your pump will deliver that flow, then that relatively short pipe won't restrict it too much'

I daresay someone will do the arithmetic...

(I reserve the right to be of no help what so ever)

Yes, no problem at all. Velocity ~ 2.2 m/s is reasonable and friction loss in 10 ft pipe is only ~ 0.5 m (0.05 bar)

Codey

Let's assume ambient temperatures and a horizontal straight pipe with no fittings.

1.5in diameter = 0.0381m

The cross sectional area of the pipe is π (0.0381m)²/4 = 1.14e-3m²

The flow in the pipe is 10m³/h = 10/3600m³/s = 2.78e-3m³/s

The average velocity in the pipe is 2.78e-3 / 1.14e-3 m/s = 2.44 m/s, which is OK, as the 'economic' maximum velocity is usually reckoned to be 3m/s for a liquid in a pipe.

Now for the Reynolds Number = velocity 2.44m/s x diameter 0.0381m x density 1000kg/m3 (roughly?) / viscosity 0.001 Ns/m² (roughly?) = 93000 dimensionless, which is well into the turbulent region above 2300, which is to be expected.

According to charts, the Fanning Friction Factor for a Reynolds Number of this size varies from 0.012 for a perfectly smooth pipe to, say 0.028 for a very rough one. Let's go down the middle at 0.02 for the sake of getting something meaningful out of this exercise, though note that PVC is smooth-ish.

The pressure drop along the pipe = 4 x Fanning Friction Factor 0.02 x length 10m / diameter 0.0381m x 0.5 x density 1000kg/m3 x (velocity 2.44m/s)² = 62500N/m² or 0.63bar.

So provided the pressure at the inlet is kept at 4bar, the pressure at the outlet should be around 3.3 to 3.4bar for a flow of 10m³/h and probably a gnat's higher, though if the pressure at the inlet drops below about 1 bar then other things might happen as the velocity couldn't be kept up enough to sustain the flow.

So the answer is probably yes according to the assumptions made in this calculation.

I'd only comment that 1.5" is the nominal pipe size. OD is 48mm and even the 15bar class uPVC has wall thickness 3.7mm, giving actual bore > 40mm.

As headloss varies ~ as 5^th power of diameter it makes a fair bit of difference.

Cheers..........Codey

Absolutely! The poster didn't state that!

If any reader wishes to re-run the calculation, feel free.

I just happen to have my "Cameron Hydraulic Data" book handy so here goes.

10M3 is 2640 gallons, so 10m3/hr is about 44gpm.

Looking at the friction data for 1-1/2" steel pipe, at 44gpm, pipe velocity is around 7 feet per second, head loss is 13 feet per 100 feet. A 10 foot length of pipe will have about a 1.3 foot head loss.

Short answer is yes you can do it.

BTW, Mr. Slack is almost correct, but his pressure drop is around 3 times too high. Pipe length is feet, not meters.

Not that I have never made that type of error!

No problem. Your water velocity is 2.21 m/s, so your frictional loss is negligible. A pump supplying a pressure of less than 4 bar will meet your requirement easily.

Just to be slightly pedantic, It's not just the pressure that's required...obviously the pump must have that flow capability in the first place. We have nice peristaltics which will do 4 bar but only at 40 mls/min

Oh dear I think I've just been stating the stupidly obvious...

Yes, but the disclaimer at the bottom of your posts will cover you from to many complaints. ;<)

For Sizing pipes for water the formula is :

Q = 3.142/4 x A2 x V x 3600/1000000

Q = m3/hr

A = mm diameter

V= Velocity for water 1.5 to 3m/s

A 40 mm pipe passes 10 m3/hr within velocity range 2.0 - 2.5 m/s.

Since the distance is not much so should be ok. However, to be on safe side take a 50mm pipe. At 1.5 m/s velocity the flow will be 10.7 m3/hr.