Delta-P Pool Drowning

[pinguy]

I came across this very interesting video explaining how differential pressure is hazardous to commercial divers. It's a little long but a good watch. The second incident they show is someone repairing a pool drain and becoming trapped underwater due to the "delta-p" (around the 4:11 mark in the video).

Delta P - YouTube

What I'm not understanding is, how can such a large pressure difference occur in a pool setup?

 

[440dodge440]

The pump is on in this situation. Most newer pools Tee the main drain into two, so if one is blocked, the water is still pulled through the other one. In addition, main drains I've seen are designed with a shape to them (not flat) to help prevent something from easily being able to conform to them and cover them completely.

 

[Divin Dave]

The instance in which the diver died in the pool is why the Virginia Graeme Baker act exists for pools which have main drains in the bottom.

 

[JoyfulNoise]

Definitely less common to have these types of accidents in residential pools as the pressure differentials are smaller and the VGB-compliant main drains make the problem less likely. However, this is a good reminder to never go swimming in the upstream side of a dam

Thanks for the YouTube link, I watched it through and it was interesting. I especially liked the part about Lock-Out/Tag-Out procedures - brought back all of my old industrial safety training memories when I used to be a working-stiff. We had LO/TO procedures for every piece of equipment in our labs and had to be able to recite the LO/TO procedures from memory when the IHS engineers would come around and do safety audits on the labs...and don't get me started about chemical-safety procedures...