# Finding pressure in gas nailer combustion

• rkcompton
In summary, the conversation involves finding the new pressure inside a combustion chamber after burning fuel and increasing temperature, using the ideal gas law and thermodynamics. It also discusses the difference between combustion and just heating something, and the factors that affect volatility of substances. Further suggestions are given for researching the thermodynamics of internal combustion engines and looking up the chemical equation for propane and oxygen combustion.
rkcompton
Problem: I need to find the new pressure inside a combustion chamber, from the burning of the fuel, and the increase in temperature, if the piston/plunger seized/
some of this is nominal, just to get a general idea of where I'm at.

Honestly it's best explained as a pipe bomb... what if i have a set volume cylinder, that has some propane with some room air in it.. somehow the propane reacts, then the pipe is thrown into a camp fire (oh no!) and the gas is heated via the cylinder to a relatively hot temp, what is the new pressure inside?
I believe, I can use PV=nRT, however because of some insecurities about what actually creates the pressure difference when something burns.. I don't know how to set it up... like, when something burns is there more moles on the new side of the eqn if there is a larger sum of coefficients in the balanced eqn? .. or is it just the actually temp change of the gas that causes it to expand.
also, why is butane more "volatile of and explosion" over propane?
hope that makes sense.. and I'm not making a pipe bomb.. or any intentional weapon for that matter..

Thanks,
K

You seem to be mixing something up here.

Combustion means you are taking CnH2n+2 and oxidizing it to O2 and CO2. This is a different process from just heating something and increasing the vapor pressure above the solution.

The former process depends on what you are combusting and under what conditions; because something like a plain old alkane would just give typical combustion products (Oxygen and Carbon Dioxide) but if there are heteroatoms around (whether in the pure substance or as impurities) you can get various other gases. This can be approximated by finding partial pressures using the ideal gas law and then finding the total pressure.

For the latter process you can probably find tables of vapor pressures as functions of temperature, I'm not sure if calculations are possible (someone more knowledgeable should have that answer).

As far as what makes things more or less volatile, its a function of intermolecular interactions where Van Der Waal's become the important one for plain old alkanes (you can think of as a function of size of the molecule, but the fundamental property is polarizability). AFAIK propane should be more volatile than butane (smaller molecular, less polarizibility and weaker intermolecular interactions). This situation changes when heteroatoms are present due to dipole or even ionic interactions.

Combustion means you are taking CnH2n+2 and oxidizing it to O2 and CO2.
...
typical combustion products (Oxygen and Carbon Dioxide)

I am sure you meant to say water H2O and carbon dioxide CO2

Ok, so to restate, yes I understand it's two separate questions; (1) how do I calculate the pressure in a fixed container after the propane and oxygen have burned (mind, this is a known amount of pure propane, and 21% of the air in the container is oxygen, and assume it burns to completion.) ? And two, if then after in the same container the temp of internal gasses was increased how do I calculate the additional pressure increase.

My guess is, that for first question, i just adjust for the difference in moles on left of Rx eqn to the mole on right.. But that seems fishy. And for the second, I think it's a liner relatiOnship since the vol doesn't change so it's just the change in temp?

I would google for the thermodynamics of the internal combustion engine, these things were researched to death.

firstly, write down the chemical equation for when propane and oxygen combine to form water and carbon dioxide.

Ideally,
For the first question you could
1. Determine the energy of combustion of propane - look it up on the iinternet.
there is a higher heating value and a lower heating value HHv and LHV. Use LHV as the water will still be a vapour state.
2. That energy of combustion is your heat Q added to your products. And your products include the nitrogen in the air that also undergoes a temperature increase.
3. Use thermodynamics to find a temperature increase of the gases, and pressure increase.
Temperature of products should be similar to adiabatic flame temperature - note the assumptions.

For the second part, thermodynamics again on the products , using a heat input from the bonfire!

so there you go.
Good luck.
and look up Boreks suggestion for more input to your problem.

256bits said:
I am sure you meant to say water H2O and carbon dioxide CO2

Yes yes I absolutely meant water and carbon dioxide (I actually made that mistake twice and then proofread the damn post and still didn't correct it). I should be sentenced to remedial Chemistry!

As far as the original question goes, depending on what type of precision you are looking for both approaches would work; estimation via using thermodynamics or finding some values under similar conditions through the literature. The literature values would probably be closer to reality as these are done via experiment in the real world, as opposed to idealizing everything via thermodynamics.

## 1. How does a gas nailer combustion work?

The gas nailer combustion process involves a mixture of fuel and air being ignited by a spark, creating a controlled explosion that propels a nail into a surface. This process is repeated each time the trigger is pulled, allowing for rapid and efficient nailing.

## 2. What factors affect the pressure in a gas nailer combustion?

The pressure in a gas nailer combustion is affected by several factors, including the type and quality of fuel used, the temperature and humidity of the surrounding environment, and the condition and maintenance of the nailer itself. These factors can all impact the efficiency and effectiveness of the combustion process.

## 3. How can I measure the pressure in a gas nailer combustion?

The pressure in a gas nailer combustion can be measured using a pressure gauge or a manometer. These tools can provide a numerical reading of the pressure, allowing you to adjust and maintain the pressure at the desired level for optimal performance.

## 4. What is the recommended pressure for a gas nailer combustion?

The recommended pressure for a gas nailer combustion can vary depending on the specific model and manufacturer. It is important to consult the manufacturer's instructions or user manual for the recommended pressure range for your particular nailer. However, in general, the pressure should be high enough to drive the nail efficiently, but not so high that it causes excessive wear and tear on the tool.

## 5. How can I troubleshoot pressure issues in a gas nailer combustion?

If you are experiencing pressure issues with your gas nailer combustion, there are a few potential causes to consider. First, check the fuel and air filters to ensure they are clean and not clogged. Also, make sure the fuel canister is properly attached and the tool is well-maintained. If the issue persists, it may be necessary to consult a professional for further troubleshooting and repairs.

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