Re: [PSUBS-MAILIST] Escape from a K250 at 200 ft

Alan,

Very interesting what your reporting here. I suggest you make your finding up in a chart then post it on the website. A chart that showed flooding at a few different depths. for both K-250 and K-350 would be great information for the community.

A K-350 is the same diameter but two feet longer in the straight portion of the hull. A K-250 has an internal VBT and batteries that aren't inside a K-350. There is probably a few extra liters in a K-350 conning tower also. The results will probably be close to adding an extra 40% to your times.

In a situation where a person was actually flooding for escape, a second or two either way wouldn't make any matter.

I had no idea of the actual flooding time and never thought about calculating it. I knew it would flood really fast at first through a 2" valve but that's about it. It's great to see numbers.

Interesting, very interesting,

Dan H.

----- Original Message -----

From: Alan James

To: personal_submersibles@psubs.org

Sent: Tuesday, August 24, 2010 4:06 AM

Subject: [PSUBS-MAILIST] Escape from a K250 at 200 ft

Hi all,

I've put some facts & figures together re flooding a K250 at 200 ft.

Firstly, sorry I move between metric & imperial. I was brought up on

imperial then N.Z. moved to metric. The metric system is great for these

soughts of calculations.

The first assumption is that the hull & hatch area displaces 1,100 liters.

The hatch 100 liters & the hull 1000 liters.

The flow figures through a 2" pipe come from table 2 on this link. It was the best I could find.

http://flexpvc..com/WaterFlowBasedOnPipeSize.shtml

These figures are approximations as the flow rate changes all the time. Also I'm not

taking into account how many or how fat the occupants are.

To fill to half way with the 2" valve at 100 psi the water will be coming in at 384 gallons per minute.

It will fill the 550 liters (132 gallons) in about 20 seconds. The air in the hull will be compressed

to half its size & will be an equivalent pressure (14.7 psi) as at 33 ft.

To fill the hull from 1/2 to 2/3 the flow pressure will be between 85 psi & 70 psi. About 340 gpm.

The volume to be filled is 183 liters ( 48 gallons ).This will take 8 &1/2 seconds. In terms of internal

pressure you have just gone from 14.7 to 29.2 psi wich is the same as diving from 33 ft to 66 ft in

8&1/2 seconds.

To fill the hull to 3/4 the pressure will be from 70 to 55 psi about 300 gpm.

The volume to be filled is 92 liters ( 24 gallons ). This will take about 5 seconds. Again this is

equivalent to going down another 33 ft. to 99 ft.

Am being kicked off the computer for the night so will leave it there.

But that is flooding so fast, I'd want to have my hand on the valve as at that rate you'd blow

your ear drums for sure. It's best to equalize your ears before they start feeling pain & in this

instance you can't reverse the pressure like while diving, by ascending.

These figures are open for correction.

Regards Alan