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by emojo 1008 days ago
I used to work for McDonald's Corp., I was told by some one in operations that the rationale for self-service drink station was that customers actually used more ice than the actual soft drink and was as a result more profitable over time/scale.
2 comments
jncfhnb 1008 days ago
I don’t think that’s correct. Sure, filling up a cup with ice can increase the margins on a drink but a hefty amount, but the margins on soda are already excellent, and most customers expect a staff made drink to be fairly full of ice to begin with. I would suspect the real reason is that filling a drink is sort of slow and you can serve more customers if they fill their own drink.
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sliken 1008 days ago
Which is of course why you can fill a cup in 1 second, but takes several seconds to fill with a drink. Also the ice comes out forcefully enough that you have to do the ice first if you don't want to make a mess.
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paleotrope 1008 days ago
Nice theory but I don't think that's true. They mix the syrup and soda water at or right before the nozzle. The ice just gets dumped from a gravity feed hopper.

If the soda water was dispensed faster it would bubble over even more so then now.

And the same exact dispensers are used behind the counter. Why would you hamstring your employees the same way.

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sliken 1008 days ago
Speed of filling isn't related to liquid velocity, but velocity x stream size. Bubbling isn't related to change in volume, but liquid velocity (and turbulence). You could double the width of the stream and fill it twice as fast with no more bubbles.

You can bet that if ice cubes cost 4x the soda that they would make difference decisions on the drink machine.

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paleotrope 1008 days ago
Isn't the bubbling/foaming due to the CO2 coming out of soda water?
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sliken 1008 days ago
Yes, but the rate is related to turbulence which generally scales with velocity. Try to fill a drink glass with high pressure soda coming through a straw would just make a fountain of foam. Poor it slowly and there will be minimal foam. To speed filling without increasing velocity widen the stream.

Somewhat related, some measure the quality of a tea kettle by the height you can pour a laminar flow into a tea cup.

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