Altitude???

[Nigels]

Questions?

If a tire is inflated at sea level to say 80psi what will the same tire read at 6000ft?

To boil 1 pint of water at 6000ft does it use more propane or less than at sea level?

Does 1 pint of water at 6000ft boil in less or more time than at sea level?

If you take your blood pressure with a meter that uses pressure (the arm band type) then do you have to adjust the readings to take into account altitude?

[LadyWindrider]

Question 1, tire inflation, doesn't matter, you are measuring the pressure inside the tire, not outside.

Question 2 & 3, if it takes longer to boil water, which it will, it will use more propane.

Question 4 on blood pressure, same as question 1, measuring inside pressure, outside pressure has nothing to with it.

Now it will also be colder at 6000 feet, does that matter? Sorry, messing with you. Pilots don't have to go on oxygen until above 10,000, so it really doesn't matter. Herk will correct me if I'm wrong.

[grhodes50]

windrider help me out. I'm a little confussed.
If I purchase a bag of potato chips in Oklahoma and travel to Colorado, the bag will be puffed up when I get there. So wouldn't that mean that outside pressure changes effect inside pressure changes?

[Nigels]

Originally Posted by grhodes50

windrider help me out. I'm a little confussed.
If I purchase a bag of potato chips in Oklahoma and travel to Colorado, the bag will be puffed up when I get there. So wouldn't that mean that outside pressure changes effect inside pressure changes?

Hence the reason for my post, I have noticed increases and decreases in tire pressures (when cold) at different campsites when the tire pressures have not been adjusted, I need to learn though how much to expect.

[LadyWindrider]

Yes, but a bag of potato chips package at sea level will be around 14.7 psi if I remember right. Now if you climb to 6000 feet, that bag may puff up, but will still have 14.7 psi in it, and long as it is sealed. It just doesn't have as much atmosphere pressure pushing it in. That is why it puffs up. Will your tires change pressure, maybe one or two pounds, but it doesn't really matter. In an average car tire, 10 degrees of temp equals 1 psi of pressure. Now if you check tires at 30 degrees before you go to work, and set them at 35 psi, and you get ready to come home and it is 60 degrees, they will be at 38 psi. Are you going to air them down, and blow them up the next morning?

Willing to help, but I don't see the point in this. Most tire gauges are only accurate to 5%, in the mid range of the gauge, so at 50 psi, you could be 2.5 psi low or high.

Your bag of chips at 6000 feet above sea level, only has about 12 psi pushing in on it, so that is why it puffs up.

Herk where are you with the formula's, been a while since I flew airplanes enough to remember all this stuff.

One last thing. If you weigh yourself at sea level, and go directly to 6000 feet above sea level, you will weigh less also.

[grhodes50]

windrider, thanks for the explanation. Good info.

[Nigels]

Windrider thanks for your expanations, any idea on the blood pressure monitor and its accuracy?

[DAISY BOYKIN]

Nigel's blood pressure monitor must be messing with his loose nuts and bolts??

[youroo]

You should not eat Tater chips while flying a airplane! They also contribute to high blood pressure! Youroo!!

[Herk7769]

Originally Posted by windrider

Herk will correct me if I'm wrong.

Don't count on it. You are correct on all counts.

[Ovair]

But but but water boils sooner at higher elevations. Therefore, if your only goal is to bring water to a boil, it should take less fuel not more.

[Rugged Brown]

A bag of chips will never last from one state to another with me.

[Glenn5995]

"Elevation" is a geographic location (earth's surface) above or below a fixed location (sea level). "Altitude" is the "up" distance between an object and a fixed reference location, as used in geometry or aviation for the distance of aircraft above sea level. "Depth" is the "down" measurement between an object and a fixed reference point.

So unless you inflate your tires and then load them into Lou's C-130, take off and then check your blood pressure while eating potato chips and watching a pot of water boil, then altitude is not really a concern. For us RVer's elevation is......well that is another story!

(Hopefully no offense - this post was meant in humor with a slight educational tidbit of info.)

[KyDan]

To answer the OP..... since outside air pressure is only 2 or 3 LB/sq in less
at 6000 vs sea level The tires would tend to exhibit 2 or 3 PSI more pressure
at altitude. It's not enough to worry about.
Also-- the air temp at altitude is typically lower and a cooler tire will
have a lower pressure so it's kind of a wash......

We did have tater chip bags to split a seam when we crossed the
continental divide at 11,000 feet last summer.
You can stick the bag with a pin and that will prevent split snack and cereal
bags without becoming stale.
Also beware when you open the ketchup at altitude!!!
Ask me how I know that

[Herk7769]

For Ovair: I know you mentioned water boiling as your only goal, but:

1) BTU available from Propane decreases significantly with Altitude.

Propane & Natural Gas Orifice Charts Ward Burner Systems

Unless you carry around a complete set of burner orifices for all your propane appliances you are stuck with those calibrated at sea level.

Thus it takes more propane for a given result (furnace heat or a given temperature in the oven or water pot) at altitude than sea level.

2) While it is true that the boiling point of water decreases with altitude, Boiling Point / Atmospheric Pressure / Altitude, it is also less "hot" when boiling.

3) Less "hot" means food takes LONGER to cook. How To Boil Water, Boiling Points of Water, High Altitude Boiling Water, Sea Levels vs. High Altitude Water Temperatures

All point to more propane used.

[Herk7769]

This article might help the OP.

Proper Tire Inflation

It also explains why running at MAX pressure on the tire is not always the best advice.

For the Nitrogen "Bulls" there is some ammo for you guys too.
(Not much but throwing you a bone here).

[Glenn5995]

Originally Posted by Nigels

Hence the reason for my post, I have noticed increases and decreases in tire pressures (when cold) at different campsites when the tire pressures have not been adjusted, I need to learn though how much to expect.

Most of that change is from temperature change, not elevation. Tire pressure will fluctuate approximately 1 lb for every 10* change in temperature. Increased pressure with higher temperatures and decreased pressure with lower temperatures.

If I check my tires "cold" on a 112* Phoenix afternoon and then drive to a campground at 9000' elevation and check them "cold" at 46* the next morning, the PSI will 8 to 10 lbs less. I usually set my tire pressure for a moderate temperature and allow them to be higher on a hot day by a few PSI and allow them to be a few PSI lower on a cooler day. Otherwise I would constantly be changing the tire pressures.

[Nigels]

Originally Posted by herk7769

For Ovair: I know you mentioned water boiling as your only goal, but:

1) BTU available from Propane decreases significantly with Altitude.

Propane & Natural Gas Orifice Charts Ward Burner Systems

Unless you carry around a complete set of burner orifices for all your propane appliances you are stuck with those calibrated at sea level.

Thus it takes more propane for a given result (furnace heat or a given temperature in the oven or water pot) at altitude than sea level.

2) While it is true that the boiling point of water decreases with altitude, Boiling Point / Atmospheric Pressure / Altitude, it is also less "hot" when boiling.

3) Less "hot" means food takes LONGER to cook. How To Boil Water, Boiling Points of Water, High Altitude Boiling Water, Sea Levels vs. High Altitude Water Temperatures

All point to more propane used.

Thanks Lou, for coming to the rescue, great info, any ideas on the blood pressure mointor?

[Herk7769]

Originally Posted by Nigels

Thanks Lou, for coming to the rescue, great info, any ideas on the blood pressure mointor?

Not really. You need to talk to a doctor or nurse about that one.

My "gut" says is does not matter because you are reading liquid pressure (blood) in millimeters of mercury lifted but in truth I have no idea.

[acadianbob]

Originally Posted by Nigels

Questions?

If a tire is inflated at sea level to say 80psi what will the same tire read at 6000ft?

To boil 1 pint of water at 6000ft does it use more propane or less than at sea level?

Does 1 pint of water at 6000ft boil in less or more time than at sea level?

If you take your blood pressure with a meter that uses pressure (the arm band type) then do you have to adjust the readings to take into account altitude?

I would think water would boil quicker and with less propane at 6000 ft than sea level because the boiling point is lower.