Liquid Flow Calculation out of a pressurized tank

Click For Summary
SUMMARY

The discussion focuses on calculating liquid flow rates from a pressurized tank, specifically addressing the influence of overpressure and gravity on discharge times. The key equation referenced is derived from Bernoulli's principle, where the exit velocity (v) is calculated using v = (2*(P_tank - P_atm) / density)^1/2. A critical aspect highlighted is the necessity of incorporating the gravitational constant (g_c) to ensure unit consistency in the calculations. Participants emphasize the importance of understanding fluid properties and pressure differentials in achieving accurate flow rate estimations.

PREREQUISITES
  • Understanding of Bernoulli's equation and fluid dynamics
  • Familiarity with pressure units (pounds-force per ft² and pounds-mass per ft³)
  • Knowledge of gravitational constant (g_c) in fluid calculations
  • Basic principles of hydraulic systems and flow rate calculations
NEXT STEPS
  • Research the application of Bernoulli's equation in pressurized fluid systems
  • Study the impact of gravitational constant (g_c) on fluid flow calculations
  • Explore methods for calculating flow rates in hydraulic systems
  • Investigate the properties of various liquid chemicals and their effects on flow dynamics
USEFUL FOR

Engineers, fluid dynamics specialists, and anyone involved in the design or operation of pressurized liquid transport systems will benefit from this discussion.

Evan Jones
I am an engineer who needs to help my chemical transport girl friend with a little basic physics. It has been about 35 years since basic physics for me so I am rusty. She wants to understand how to calculate the following:

She drives a large tanker (cylindrical) which carries a variety of liquid chemicals and wants to understand how to calculate the discharge times. When they discharge the chemicals at the destination, they pump (and maintain) an over pressure of air in the tank during the discharge process. The fluid drains through a hose into an open (non-pressurized) tank. I know the fluid properties of the various chemicals, I just need to see if anyone can assist with the calculation. Am I just adding the force of the over pressure to the force due to gravity? If this were an open tank, I know how to make that calculation from the tank, through the hoses, and into the destination tank. I just don't understand how to account for the over pressure.
 
Physics news on Phys.org
The answer to your question is Yes.
 
Chestermiller said:
The answer to your question is Yes.
Can I ask you @Chestermiller to please expand on your answer. I am working on a similar problem whereby I need to determine the flow rate out of a tank that is under constant pressure from a hydraulic ram plate. I have looked at Bernoulli's equation but, I cannot make the units cancel out when calculating the exit velocity. Specifically, the term (P_tank - P_atm)/ density. The units for Pressure are in pounds-force per ft^2 while the units for density are in pounds-mass per ft^3. What am I missing for the equation v = (2*(P_tank - P_atm) / d)^1/2. Any assistance is much appreciated.
 
Last edited by a moderator:
fcroma said:
Can I ask you @Chestermiller to please expand on your answer. I am working on a similar problem whereby I need to determine the flow rate out of a tank that is under constant pressure from a hydraulic ram plate. I have looked at Bernoulli's equation but, I cannot make the units cancel out when calculating the exit velocity. Specifically, the term (P_tank - P_atm)/ density. The units for Pressure are in pounds-force per ft^2 while the units for density are in pounds-mass per ft^3. What am I missing for the equation v = (2*(P_tank - P_atm) / d)^1/2. Any assistance is much appreciated.
You need to multiply by g_c.
 

Similar threads

Undergrad Flow rate calculation of coating application
  • · Replies 30 ·
2
Replies
30
Views
3K
High School Pumping water upwards into a large water tank
  • · Replies 3 ·
Replies
3
Views
2K
High School Question about pressure of a liquid
  • · Replies 8 ·
Replies
8
Views
875
High School Will there be water coming out of the last hole?
  • · Replies 17 ·
Replies
17
Views
2K
Graduate Air flow through a hole in a submerged pressure tank
  • · Replies 13 ·
Replies
13
Views
21K
Graduate Calculating Drain Time of a Tank with Closed Outlet: What is the Formula?
  • · Replies 14 ·
Replies
14
Views
9K
Graduate Calculating Filling Time for a Diving Tank with Changing Hydrostatic Pressure
  • · Replies 2 ·
Replies
2
Views
2K
Graduate Pressure drop across a valve in tank
  • · Replies 4 ·
Replies
4
Views
2K
Undergrad Pressure Gradient for Nitrous Flow
  • · Replies 2 ·
Replies
2
Views
2K
Calculating flow rate when emptying liquid from a closed-top tank
  • · Replies 11 ·
Replies
11
Views
4K