Why don't funnels drain underwater even with a check valve installed at the bottom?

Why does water flow stop when a funnel is submerged underwater even though there is a check valve installed at the bottom?

A funnel doesn't drain underwater even with a check valve installed at the bottom because of the pressure exerted by the water on the funnel. The pressure difference between the inside and outside of the funnel plays a crucial role in the water flow.

Pressure and Water Flow in a Funnel

Water Pressure: When a funnel is placed above the water level, the pressure exerted by the water at the inlet of the funnel is equal to the atmospheric pressure. However, as the water level rises inside the funnel, the pressure exerted by the water increases.

Impact of Water Weight

Heavy Liquid: Water is a heavy liquid, which means that as the water level rises inside the funnel, it exerts more pressure on the funnel due to its weight. This increase in pressure eventually equalizes the pressure inside the funnel with that outside the funnel, causing the water flow to stop.

Role of Check Valve

Check Valve Function: The check valve installed at the bottom of the funnel prevents water from flowing back into the funnel once it has drained. However, it does not prevent the pressure buildup inside the funnel caused by the rising water level.

In conclusion, the combination of water pressure, the weight of the liquid, and the check valve mechanism all contribute to why funnels do not drain underwater even with a check valve installed at the bottom.