How to keep liquid flow rate constant

[sherif adel]

How to keep liquid flow rate constant!

hi, my grad. project is automated filling machine and am going to use a gravity liquid (water) filler tank ... my question is how to keep the flow rate from the tank nozzle constant while the liquid level in tank is changing as it fills every bottle ?

 

[Integral]

Variable orifice size?

Why is constant flow rate important?

 

[Q_Goest]

Pressure regulator with restriction downstream.

 

[sherif adel]

@ Integral
no the orifice size is fixed .. and i want fixed flow rate to keep the machine production rate constant whatever how many bottles are being filled

@ Q Goest
sry i`m an electrical engineer and this is not my field of study, so can u please tell me how can i regulate the pressure inside the tank

 

[Q_Goest]

You don't regulate the pressure inside the tank. You would have a pipe coming off the tank and going into a pressure regulator. That regulator sets the pressure in the pipe downstream of the regulator. Now pipe that into a restriction such as a needle valve and adjust the valve till you get the right flow rate. Since the pressure upstream and downstream of the valve is always constant, the flow through the valve will always be constant. To do this properly, you may need more than head pressure (ie: more than a few psi). You may want to consider a pressurized tank or elevating the tank enough to provide some head pressure.

 

[flatmaster]

I suggest keeping an open tank with a constant head. You can have the water leak over the side, but this will waste some water. Perhaps you could use a float and valve like you find in the back of a toilet. Simpler and cheaper than a regulator.