Venting liquid from a bottle question.

[Steveaa123]

I am working on a project, where I am pouring liquid from a bottle with a lid on it. I need a vent hole to allow the liquid to escape from the bottle. Is there a way to calculate how big my vent hole needs to be to get the maximum volume out of my bottle?

Thanks,
Steveaa123

 

[Zapster]

Does this question relate to a school project?

I am pouring liquid from a bottle with a lid on it. Remove lid, it will help tremendously.
Is there a way to calculate how big my vent hole needs to be to get the maximum volume out of my bottle? Volume of the bottle should remain constant regardless of vent hole. Perhaps you mean flow which would be volume/time.

My apologies if English is your second language. Match your volumetric flow rates for fluid leaving the bottle and air entering the bottle.

 

[Steveaa123]

Hi Zapster:

This is my first time at using this website. I am a Tech support and I have never worked with anything like this before. So, sorry for not sounding like I know what I am talking about.

My current project requires that I understand the relationship between liquid flow and the vent hole in a corked bottle. My task is to find the smallest vent hole that would not affect the flow rate of the liquid.

Thanks again for the help.

Steveaa123

 

[gfbotha]

I suggest one first calculates the max liquid flow rate through an orifice for an assumed open container. There are formulas to estimate just that. Then, as suggested by Zapster, equate this flow rate to the flow rate of air required to enter the container. Using an expression for the known flow rate of air through an orifice, you should be able to evaluate different vent hole sizes until you find the required pressure difference is negligibly small.

 

[jbthiel]

just remember that the flow of the liquid through the orifice with depend significantly on the fluid's viscosity and the orifice geometry.

And I suppose that you don't want any pressure drop through the venting orifice. Otherwise it would be restricting some from by changing the pressure differentials accross the fluid orifice.

 

[zekeman]

You start with a full bottle and call the volume of air the bottle at any time, V and the two orifices A1 and A2 for the air vant and the liquid vent.
First write the gas law
PV=WRT and taking one derivative

1)V*dP/dt+P*dV/dt=RT*dW/dt
Next the flow of fluids
2)dV/dt=kA2(-Pat+P+Rho*h)^.5 for liquid flow out(assumes bottle held upright and h is the height of liquid
3)dW/dt=RhoAir*K1*A1*(Pat-P)^.5 air flow in
Finally, the rate of height change
4)dh/dt=-dV/dt/Ab
Ab = area of bottle crossection
variables are P,V,h,W
parameters are A1 and A2
You should be able to solve this set by assuming some allowable flow rate to get A2, the air vent
Good luck




































W/dt

 

[irasamm]

I assume that the hole in your bottle is the limiting factor, not the liquid outlet. Cut the end off of your bottle which should produce the maximum possible flow rate. Time how long it takes to empty the bottle with a huge hole (you know the volume). Back into the size of your hole based on this maximum flow rate.