Fluid Flow out of a Liquor Bottle

In summary, the conversation discusses the potential issue of using a bottle to let liquid flow out instead of pumping it, as the flow rate may change as the height of the fluid decreases. However, it is noted that bartenders are able to accurately measure their pours by counting time. It is questioned whether this method remains accurate as the bottle becomes more empty. The conversation also mentions a resource for further information and suggests conducting an experiment with a bottle to observe the flow. Finally, it is mentioned that the flow rate may remain constant if there are other factors restricting the flow, such as the weight of the liquid, air pressure, and viscosity. However, it is also noted that the environment of a bar may not be as controlled as a laboratory,
  • #1
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I was working on a project for which I was considering letting a liquid flow out of a bottle rather than pump it out, but I know that the flow rate changes as the height of the fluid within the container changes, which is an issue. I then remembered that bartenders count time to measure their pours. I can't see any way this is remains accurate as the bottle becomes more empty. I could only imagine that they make small, unconscious adjustments as this happens.

Can anyone see any way that the flow rate may remain constant out of a liquor bottle for varying heights of the liquor?
(I found this page to be a good resource: http://www.engineeringtoolbox.com/bernouilli-equation-d_183.html)
 
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  • #2
Welcome to PF;
Good observation. You should get a bottle, any old bottle, and upend it and see what happens.

Note:
Bar bottles usually have a special nozzle
poured measures are not very accurate even if the bartender is counting time.
(Ask yourself - how accurate does it need to be?)

A fluid may flow at a constant rate out a hole if there is something else restricting the flow.
Consider - there is the weight of the liquid above the hole, the air pressure, and the viscosity of the fluid.
The flow is likely to be uneven if the air has to push its way through the liquid to get into the bottle ... if the air cannot get into the bottle, the flow will slow and stop.
 
  • #3
And remember, you are in a bar, not a lab, where different protocols are supposed to apply.
 

Related to Fluid Flow out of a Liquor Bottle

1. What causes the fluid to flow out of a liquor bottle?

The fluid flow out of a liquor bottle is caused by the difference in pressure between the inside and outside of the bottle. When the bottle is opened, the pressure inside decreases, allowing the fluid to flow out.

2. How does the shape of the bottle affect the fluid flow?

The shape of the bottle can affect the fluid flow by creating different levels of pressure inside the bottle. For example, a narrow neck bottle may have a higher pressure inside, resulting in a slower flow, while a wide neck bottle may have a lower pressure and a faster flow.

3. Does the temperature of the fluid affect the flow out of a liquor bottle?

Yes, the temperature of the fluid can affect the flow out of a liquor bottle. As temperature increases, the molecules in the fluid move faster, increasing the pressure inside the bottle and resulting in a faster flow.

4. How does the viscosity of the fluid impact the flow out of a liquor bottle?

The viscosity, or thickness, of the fluid can affect the flow out of a liquor bottle. A thicker fluid will flow slower due to increased resistance, while a thinner fluid will flow faster. This can also be affected by the temperature of the fluid.

5. Can the fluid flow out of a liquor bottle be controlled?

Yes, the fluid flow out of a liquor bottle can be controlled by adjusting the pressure inside the bottle. This can be done by changing the shape or size of the bottle, or by using a valve or nozzle to regulate the flow.

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