Submarines, and barometers.

[Beau Cassidy]

Yup. But because the pressure, humidity and temperature in a sub are all very closely controlled, a barometer on a submarine is about as useless as brakes.

That is about what I was thinking before getting to Jim's reply. Gee whiz? Is it gonna rain in a submarine or is a cold front gonna come thru? I guess if the pressure drops too much you better be looking for a leak!

[Jammer Six]

Certainly all of us have dropped a 1/4 stick in a lake before?

Yup.

Made it soggy and hard to light.

[starmac]

Certainly all of us have dropped a 1/4 stick in a lake before?

ER not to build a skating rink. lol

[fatnhappy]

I'm considering a new approach to ice fishing this season.

Well, if you use dynamite stand as close to the hole as possible.

[Tom-ADC]

From a friend of mine a submarine chief.

Oh my, you fellas!
The depth guages are sealed against atmospheric pressure so that they are not affected by it. Similiar to bourdon
tubes, but not the same. Very accurate, the shallows are good for at least 6" changes in depth.
2 types of barometers on submarines. 1 type in mc-neuvering and control (only reads in inches of water + or minus
surface atmospheric which is zeroed). The other is a special altimeter which acts as a barometer down in the
diesel booth. Fark IF I KNOW why we have that 60's era fighter jet component, but it's about 60K of we don't use
it. BUT, I can tell you immediately when the head valve goes shut, LOL!
Pressure is monitored and regulated by daily operations to about + or - 2 - 3 inches of water from sea level pressure.
Natural losses in pressure come from the co2 scrubbers pumping co2 overboard so there are times when we come up just
to "equalize". The O2 generators also add to put a positive pressure on the boat from the water conversion. Then you have
cyclic air consumtion that happens from air operated equipment.
So easy, an A'gangr can do it!



hagar

[wallenba]

The only reason they might have one in a sub, that I can think of, would be to monitor the regulated pressure inside. If the sub was diving deeper and the pressure hull was being squeezed, I guess it could force the pressure higher. Commercial aircraft cabins have a constant pressure inside, regulated by an outflow valve and compressed air from one of the engines compressor stages. So a sub might have to have a similar system to deal with the reverse situation.
If the crew had to escape the sub for any reason by surfacing, they would have to be breathing the same pressure as at sea level, or suffer physical problems.

[Mud Eagle]

The only reason they might have one in a sub, that I can think of, would be to monitor the regulated pressure inside. If the sub was diving deeper and the pressure hull was being squeezed, I guess it could force the pressure higher. Commercial aircraft cabins have a constant pressure inside, regulated by an outflow valve and compressed air from one of the engines compressor stages. So a sub might have to have a similar system to deal with the reverse situation.

Pressurized aircraft have altimeters that read the pressure altitude outside the aircraft (and display it in terms of altitude) and cabin altimeters that show the pressure inside (and either display it in terms of pressure differential or altitude).

Subs have depth gauges that read pressure outside the hull and display it in terms of depth...no doubt they have a gauge that displays pressure inside the hull.

It would be just as important to know what the pressure is inside a sub as it is to have a "cabin altimeter" in a pressurized aircraft: without it, it is impossible to know if the systems that keep the interior pressures (and thus keep the human occupants conscious or alive) are working.

[waksupi]

From a friend of mine a submarine chief.

Thanks Tom, I think you have it covered like a fat lady on a pot!

[wallenba]

Pressurized aircraft have altimeters that read the pressure altitude outside the aircraft (and display it in terms of altitude) and cabin altimeters that show the pressure inside (and either display it in terms of pressure differential or altitude).

Subs have depth gauges that read pressure outside the hull and display it in terms of depth...no doubt they have a gauge that displays pressure inside the hull.

It would be just as important to know what the pressure is inside a sub as it is to have a "cabin altimeter" in a pressurized aircraft: without it, it is impossible to know if the systems that keep the interior pressures (and thus keep the human occupants conscious or alive) are working.

Commercial airliners maintain a cabin pressure equivalent to about 8000 feet above sea level. They maintain that, just the way I described, or things have changed since I was an active A & P. In this instance, I was just describing the way it is done, not measured. Yes, it is based on a pressure differential, just as engine power is.

[JIMinPHX]

Commercial airliners maintain a cabin pressure equivalent to about 8000 feet above sea level.

That's the current standard, assuming that all systems are working properly. The new Boeing 787 is spec'd out to pressurize at a lower altitude for improved passenger comfort. The humidity level on them is supposed to be better too. I haven't had the opportunity to hitch a ride on one yet to check it out for myself.

[JIMinPHX]

Do Ya really need a barometer on a Sub to know it's wet outside ?...

If I was on a sub & obummer told me it was wet outside, I'd want independent confirmation.

[Mud Eagle]

Commercial airliners maintain a cabin pressure equivalent to about 8000 feet above sea level. They maintain that, just the way I described, or things have changed since I was an active A & P. In this instance, I was just describing the way it is done, not measured. Yes, it is based on a pressure differential, just as engine power is.

8,000 cabin altitude is the standard in commercial ops.

In the F-15E, the pressurization schedule depends on altitude: the schedule holds ambient pressure until 8,000', then 8000' until the low 20s, and then follows the equation [(altitude-8)/2].

I have some time in the Beech King Air, and there you manually dial in a cabin altitude, or a differential in PSI.

[bigjason6]

Kinda like arguing with a guy about if the light in the refrigerator really does go out when ya close the door.

Bob

Bob, there's a little penguin living behind the ice cubes that turns out the light when you close the door.

[wallenba]

Kinda like arguing with a guy about if the light in the refrigerator really does go out when ya close the door.

Bob

Another Schrodinger's cat?