[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [PSUBS-MAILIST] Speedometer

Yes.. and there were many typos..
and errors, specifically that you must convert the litres into cubic cm, which is just a factor of 1000 
so the proper conversion, (to km/hr NOT km/s as I first wrote)
is:
V=G*7.16283*R(cm)^2


EM.
PS.
I also realise that the word you were looking for is 'through'
Sorry for the goof, I am not concentrating properly..
(need some orange juice, preferably the concentrated variety)

Erik Muller wrote:


Hi Pierre,
Im a little confused, I think GPM = Gallon per minute... am I wrong?
I will assume that GPM = Gallon per minute.. and continue with the conversion.
The best way might be to calibrate it using a boat with another flow meter. i.e. tow your flow meter behind you at a range of known water speeds and mark it off on the meter. 

Alternatively:
To get from gal/sec to km/hr you have to convert between the antiquated, outdated and useless Imperial system, to the system that the rest of the world uses (derived and maintained by your ancestors, the French). 

A gallon is about 3.8 litres (if you are using US gallons).
You need to know the cross sectional-area of your pipe, or more basically, just the radius, R.
Since the water flow is just a flux, i.e. so many squared meteres x meters per second, you can just multiply the flow rate by the cross sectional area of your pipe. 
Then you convert from cm/min to km/hr

So to convert from gal/min to km/hr you use this equation:

V=G*A*C
Where V is the velocity (km/s), G is the flow rate in gal/min and C is some factor to convert between systems yet to be defined. 

So, with

A=pi*R^2
(R is radius of pipe in cm)

and then,

C=F(gal to litres)*F(cm to km)/F(min to hr)

C=3.8*(1/100,000)/(1/60)
C=0.00228
so:
V=G*0.00716283*R(cm)^2


I think.
EM.

Ps.. I think the word you are after is 'throughput'
PPs.. I think you should get a large throughput system, since I imagine there will be significant backpressure from small diameter pipes. 
EM.


Pierre Poulin wrote:


Hi all!

I just had another "innovative" idea.
I just bought for my work a flow meter (Gallon per meter) And when searching for it I noticed that it is also available in 0-2GPM.
Maybe we could use that to convert it to knots or KM/H or whatever. We could just place the meter in the water with a small pipe on both ends and watch the meter thruthht (can somebody tell me how to write that word please?) the front viewport.
---------------------I------------------I--------------------------------- 
                    I flowmeter   I
    in pipe       I      gpm      I    out pipe
---------------------I------------------I--------------------------------- 


Any tough on that?

Pierre "looking for a manager" Poulin

_________________________________________________________________
MSN Messenger : discutez en direct avec vos amis ! http://messenger.fr.msn.ca/