Vessel sink not draining causing flood

[frank999]

Hi,
I have had to have one of these silly Vessel sinks installed in a toilet - which has overflowed and caused a flood resulting in damage to equipment.

I think the flat grid drain type installed is at fault, anyone have similar experience ?

I can replace the drain for an umbrella type that might drain better, which would be the easiest solution, and/or also fit an air admittance valve, but unsure if this valve option would help (ie the pull and volume of water are low, would a valve work correctly here).

More info ...

The sink has no overflow. The faucet is nothing fancy, the flow is quite restricted, gentle in fact. The drain is the flat grid type.

This week some donkey left the tap running, in this sink, the water did not drain as expected and flooded part of the property.
The P trap and pipes (32mm) all appear clear.

The flood was caused - from what I can understand the drain holes trapping air and stopping the flow of water.

I have tested this by watching the sink fill, then breaking the trapped air (causing the air seal) allowing it to then drain - until air gets trapped again a few moments later.

Umbrella type drains work better apparently

The waste is a flat grid unslotted type:

 

[oldbutnotdead]

How much fall have you got on the waste pipe? And how long a run of 32mm is it? (Insufficient fall or excessive small bore runs will cause that sort of issue, if the water drains quickly air won't get trapped).

EDIT If it's a workplace or used by people who don't care then fit a different tap- either push or proximity sensor

 

[DiyNutJob]

Don't go umbrella type. It will seize and you will be banging away with a hammer in the bathroom all the time. Get the plug on a chain type. They never fail.