dishwasher drain

Dishwashers in this part of the US have a vent in the drain line. The vent is at counter height, between the dishwasher outlet and the sink drain.
Several people I know have removed this vent and connected the dishwasher outlet to the sink drain, just above the trap.
Question: what is the purpose of this vent?
Thanks.
    - Bryan
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It's above the sink height, so when you drain the sink it doen't fill the dishwasher.
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Hi,
Some plumbing codes still require the air gap in the drain and some do not require it. The air gap basically prevents water from flowing backwards.
http://www.repairclinic.com/referral.asp?R 3&NG4608 Air Gap Kit prevents back-siphoning of contaminated water from your food waste disposer, drain or sink into the dishwasher.
jeff. Appliance Repair Aid http://www.applianceaid.com /
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Thanks! Exactly the information I was looking for.
    - Bryan
jeff wrote:

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Your welcome!! :)
jeff. Appliance Repair Aid http://www.applianceaid.com /
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