How to keep liquid flow rate constant

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SUMMARY

This discussion focuses on maintaining a constant liquid flow rate from a gravity-fed filling machine, specifically for water. The key solution involves using a pressure regulator downstream of a fixed orifice size to ensure consistent flow despite varying liquid levels in the tank. It is recommended to maintain an open tank with a constant head pressure, potentially utilizing a float and valve mechanism for simplicity and cost-effectiveness. The discussion emphasizes that regulating pressure inside the tank is unnecessary; instead, the focus should be on downstream pressure management.

PREREQUISITES
  • Understanding of fluid dynamics and flow rate principles
  • Familiarity with pressure regulators and their applications
  • Knowledge of fixed orifice flow mechanics
  • Basic concepts of gravity-fed systems and head pressure
NEXT STEPS
  • Research the design and operation of pressure regulators for liquid systems
  • Explore the use of float valves in maintaining water levels
  • Learn about the impact of head pressure on flow rates in gravity-fed systems
  • Investigate the implementation of needle valves for precise flow control
USEFUL FOR

Engineers and technicians involved in designing automated filling machines, fluid dynamics specialists, and anyone seeking to optimize liquid flow control in gravity-fed applications.

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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