[Marmot]

Originally Posted by sbmar

It's trading a large surface area at low pressure for the velocity of the gases and water with the result being able to lift a water column much higher than the engine normally could without exceeding back pressure limits.. In a well designed lift muffler, it's typical to see 3/4 PSI lift water 3-4 ft ................Yes I know, a totally different subject but thought the analogy may help save our friend from being hung out to dry. ..

Be careful ... you are also confusing force with pressure.

If you have 3/4 psi you can lift seawater a little over 20 inches, the size of the pipe it's in is irrelevant, it could be 1mm or 10 meters in diameter, the pressure to lift it is the same.

What do you believe to be the back pressure limit for a marine diesel?

[Marmot]

Originally Posted by 61c40

I forgot to add that its the same princpal as a super soaker water toy

You're all wet mate. The pressure at the entrance to the nozzle of your water toy is the same as it is on the face of the piston. It is nearly zero as it exits the nozzle.

I suggest that if you refer to Mr. Bernoulli, at some point you will realize that the pressure across the nozzle must drop.

Hint: There is a difference between pressure and energy. There is a difference between pressure and force.

And I forgot to add, attempting to ridicule screen names doesn't increase your math skills or engineering knowledge.

[K1W1]

Originally Posted by sbmar

Maybe what our "250 guy" meant was similar to having 500 sq inches of surface area in an enclosed container, add 1/2 PSI to the enclosure, and then you would have about 250 lbs pressing evenly on all surfaces--But it's still 1/2 lb per square inch................???????????????????????????


Tony

Hi,

I read some of your posts on the other forum where you contribute all the time and are a moderator.

I thought you were pretty knowledgable but following the quoted text above wonder.

Posting junk like you just did really calls into question how much you actually understand about fluid and gas laws.

If you have 1/2" PSI per Sq Inch in the free space in your tank ( above the liquid level) that is all you have it is not 1/2" multiplied by the surface area of the tank top. I know fractions can be confusing ,This is why mWc is a much easier standard for people to understand.

[sbmar]

I think I may have not explained the point I was making properly... Yes, you still have 1/2" PSI (like I said) but 1/2" PSI acting on the the 500 sq inch surface area of the tank walls (or a piston if that makes it easier to understand what I was referring to) can lift 250 lbs, and on those 500 Sq inch walls, you have 250 Lbs of force spread out evenly try to push the wall out... That's all I was trying to say as maybe that's what are poster was referring to.....

As to exhaust pressure limits and diesel engines that was asked above-- Most manufacturers of realitively modern engines have maximum limits in the 1-2 psi range (20-60 inches of water column or 2-5 " Hg) .. These numbers are close enough for most preliminary exhaust design work..

Yes, you guys take no prisoners..

Tony

[Marmot]

Originally Posted by sbmar

I think I may have not explained the point I was making properly... Yes, you still have 1/2" PSI (like I said) but 1/2" PSI acting on the the 500 sq inch surface area of the tank walls (or a piston if that makes it easier to understand what I was referring to) can lift 250 lbs, and on those 500 Sq inch walls, you have 250 Lbs of force spread out evenly try to push the wall out...

No, you have 1/2 pound per square inch spread out evenly. It's a tank, it has 1/2 psi on its surface and that won't change if that surface is round, square, 1 square inch or 1 square mile.

What you are saying is no different than stating that since atmospheric pressure is 14.7 psia there is almost 34 tons pushing down on a 4X8 sheet of plywood ... it sounds all techie and exciting but really means nothing.

The crap headed for the sky because it was accelerated by tank pressure through the nozzle formed by the pumpout connection.

I don't understand why it keeps flowing here.

Yes, you guys take no prisoners..

Not when they keep charging the trenches, even if they are shooting blanks.

[sbmar]

Ok, you win, I loose.....................Obviously we have a language barrier, for sure we are on different frequencies, and we may even be on different planets............

Sorry I ever butted in..

Tony

[OutMyWindow]

Originally Posted by sbmar

Yes, you guys take no prisoners..
Tony

Yes, you have to be on your toes with the tech guys, but deep inside they are * warm and fuzzy

* Not speaking from personal experience, attitude may vary pending current or past day/weeks events, amount of alcohol in the system, missed lunch or foul weather.