Hello,
I have a brand new 5PII combustion powder gun, I would like to know if it is possible to decrease flame temperature. I read an old thread in this forum about changing acetylene to propane, will the gun work?

thanks a lot

Dear Nile,
The temperature possible to achieved with normal combustion guns, is entirely depending on the properties of the gas combination used, where acetylene has the highest temp.
To decrease the temperature for a 5PII gun, I think the most practical way is to use Hydrogen instead of Acetylen. (Actually, I don't know if there are any Propane nozzles available?)
br bjarne

Hi Nile

to the Surface Engineering Forum.

Many years ago, I remember using a 5P or possibly a 6P gun using propane and air (not oxygen) to spray nylon and some other plastic materials. To be honest I can't remember how I know propane hardware appears not to be available for the 5P-II. May be I just got away with using standard hardware or maybe had access to special syphon plugs/nozzles.

Why do want to reduce flame temperature?

Thank you Gordon and bhellman for your answers,
I?m trying to simulate a flame in coal combustion temperatures, ideally around 1500-1700?C. The 5PII is designed for acetylene and hydrogen. At the moment I have managed to decrease flame temperature to 1600?C reducing acetylene flow, but flame goes back with risk of overheating the nozzle. Moreover, once I pull the trigger and the solid goes through the flame, T rises to 2300?C.
I will try with diluted acetylene, and with H2.
I would be interested in previous experience in projecting for instance polymers with the 5pII, as you mentioned, if special nozzels are needed (not in the catalogue) or special gas compositons.
Again thanks a lot,

nile

Hi Nile

I think the only way you will really get down to those flame temperatures is by dilution of the flames reactants, like in using air instead of oxygen, where nitrogen acts as the relatively inert dilutant. May be worth careful experimentation to see if you can get a stable flame through your existing hardware using air instead of oxygen. You already seem to be using the gun well away from standard procedures anyway .

Thanks Gordon
I have to try with H2, I will try with air as well instead of O2, and I have found in the lab a cylinder with diluted acetylene in N2, its merely a 9% I will try but I?m not sure it?ll work. I?ll tell you my progresses!

regards,

Nile

Hi Nile

Thanks, I would be intersested in how you get on with your project. Using air instead of oxygen is one way of diluting the reactants in the flame, but diluting your fuel gas with say nitrogen is equally another. If you can modify your set-up to include a seperately monitored flow of nitrogen to mix with either fuel gas or oxygen would give greater control ( be careful, consider any flow back conditions) though not the simplest or economic route.