|Topic Review (Newest First)|
|10-18-2007 03:39 PM|
"Nitrogen is an inert gas and is not chemically active."
"Air, freon, water, propane, oil, and so on and so on will react to changes in temp. My point is that nitrogen will not and makes a better gas to check for leaks."
Should have read that nitrogen is considered an inert gas and is not considered chemically active.
My second statement should have read that considered dry,nitrogen will not contract and expand as great to changes in temperature and makes a better gas to check for leaks.
In context of the original question, I considered original statements correct. I was relating nitrogen to the other gases available to a DIY (compressed air, propane, ands so forth). Outside of the question and I can see where my statements may have seemed slightly bold and partially incorrect and have adjusted accordingly.
If there is something better for pressurizing and leak testing piping that is easily accessible, please let me know.
Sorry about being so late to respond, reality is getting in the way of my fantasy.
|10-15-2007 07:49 PM|
Like SD said (PVT), If the temp increases, and the gas is stored in a sealed container, the pressure will change. The ideal gas law works for all gases, nitrogen included.
Nitrogen is mostly inert (not fully inert), and is used so frequently because it is so widely available (78% of the atmosphere by volume).
|10-12-2007 03:23 PM|
Might want to check your basic chemistry again. All gases expand and contract to some degree with changes in temperature including Nitrogen. Nitrogen is generally used since it won't generally contaminate the system or cause corrosion or other problems.
The ideal gas law basically states:
where P is pressure, V is volume, n is the number of moles, T is the temperature in degrees Kelvin, and r is the universal gas constant. If the temperature changes, the volume will either increase or the pressure will.
|10-12-2007 02:06 PM|
Nitrogen is a Group 15 element. The element seemed so inert that Lavoisier named it azote, meaning "without life". Nitrogen gas is colourless, odourless, and generally inert. As a liquid it is also colourless and odourless. Prof. James Marshall U of North Texas
Nitrogen is the recommended gas for leak testing, purging, and brazing In the HVAC & R industry.
Air, freon, water, propane, oil, and so on and so on will react to changes in temp. My point is that nitrogen will not and makes a better gas to check for leaks.
|10-12-2007 10:26 AM|
|sailingdog||Nitrogen is not a noble gas, and as such is not inert. However, it is far less active than most other common gases.|
|10-12-2007 09:02 AM|
The pressure guage is downstream of the tank valve, and its sole purpose is for testing the propane system for leaks when the manual tank valve is CLOSED. The guage is never used to measure the pressure in the tank, which as you correctly point out is largely meaningless information.
|10-12-2007 08:16 AM|
In English, to be inert is to be in a state of doing little or nothing.
In chemistry, the term inert is used to describe something that is not chemically active. The noble gases were described as being inert because they did not react with the other elements or themselves. It is now understood that the reason that inert gases are completely inert to basic chemical reactions (such as combustion, for example), is because their outer valence shell is completely filled with electrons. With a filled outer valence shell, an inert atom is not easily able to acquire or lose an electron, and is therefore not able to participate in any chemical reactions. For inert atoms or molecules, a lot of energy is involved before it can combine with other elements to form compounds. A high temperature and pressure is necessary, and sometimes requires the presence of a catalyst. Wikipedia
Nitrogen is an inert gas and is not chemically active.
|10-12-2007 06:43 AM|
Guys... something is not adding up here.
The pressure should not drop until the tank is exhausted. The propane is in liquid-gas equilibrium in the tank, and the guage pressure will monitor the vapour pressure of the gas on top of the liquid. The vapour pressure is dependent only on tank temperature, and not content (well, not until it is about to run out that is).
Measuring the content of the tank is normally done by weight, with a spring balance. Pressure does not tell us much.
|10-12-2007 01:07 AM|
The 24 Hour period intrigues me. Does that mean you leave your gas valve open all the time ?
Asking the question of everyone else, how many of you don't close off your gas supply when you finish using the stove etc ?
I can't believe that anyone would leave a gas line open permanently. Seems terribly silly to me.
ps - Brak answered my first question while I was still typing.
|10-12-2007 01:01 AM|
I know, this is why my new propane locker was placed in the cockpit - for easy access, so that I won't have an excuse not to turn off the tank when done cooking or for the night.
I suppose the downside is that a tank is so close to everything, but on a boat it is kinda hard to keep things "far" anyway, what with limited space and all.
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