How to keep liquid flow rate constant

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Discussion Overview

The discussion revolves around maintaining a constant liquid flow rate from a gravity-fed tank in an automated filling machine project. Participants explore various methods and considerations for achieving this consistency despite changing liquid levels in the tank.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant inquires about methods to keep the flow rate constant as the tank level changes.
  • Another suggests using a variable orifice size but questions the importance of a constant flow rate.
  • A pressure regulator with a downstream restriction is proposed as a potential solution.
  • A participant clarifies that the orifice size is fixed and emphasizes the need for a constant flow rate to maintain production efficiency.
  • One participant advises against regulating the pressure inside the tank, recommending instead to use a pressure regulator downstream of the tank.
  • Another participant suggests using an open tank with a constant head, mentioning the possibility of using a float and valve system for simplicity and cost-effectiveness.

Areas of Agreement / Disagreement

Participants present multiple competing views on how to achieve a constant flow rate, with no consensus reached on the best method. Various approaches, including pressure regulation and maintaining a constant head, are discussed without agreement on a definitive solution.

Contextual Notes

Participants express uncertainty regarding the effectiveness of different methods and the implications of head pressure on flow rate. Some suggestions may depend on specific conditions or setups that are not fully explored.

Who May Find This Useful

This discussion may be of interest to engineers and students working on fluid dynamics, automated systems, or those involved in designing filling machines.

sherif adel
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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 ?
 
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Variable orifice size?

Why is constant flow rate important?
 


Pressure regulator with restriction downstream.
 


@ 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
 


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.
 


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.
 

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