Corrosion Issues

When propane is burnt, you get mostly carbon dioxide if the air supply is sufficient. Water vapor is also generated but carried off in the exhaust gasses. Should be no different from the operation of other typical gas stoves.

Incomplete combustion is going to be a greater concern to the chef as Carbon monoxide has a strong affinity to the blood and will kill them for lack of oxygen in their blood stream.

yea, but what IS the chemical reaction with the steel during incomplete combustion? (which is in most allpiances above 1000'.) My bad , should have posted in chemical science. Also, I think some of the water vapor combines as part of the corrosiveness this mixture has on the burner. As the burner degrades the flame efficiency suffers. Ask the "optimizers" who monitor the "big boilers".

SH__ in SHI_ out.

Several issues are visible in this question:

1. LPG(Propane) is usually quoted at 2,500Btu/ft3. Some if not all Natural Gases (Methane plus odds and sods) is usually around 950-1100Btu/ft3. So what is the fuel.
2. Is the range an medium duty open top or heavy duty solid top?
3. Does the corrosion occur on the burners themselves? Then probably the range is not being used hard enough as the water in the products is condensing on cold surfaces and dripping onto the burner. This usually starts off looking like light brown rust spots.
   
4. The burner itself has not been described but given the appliance it is likely to be of the type known as atmospheric injected. This means that the Kinetic Energy of the gas under very modest pressure induces or sucks ambient air into the mixing tube before the gas/air mixture issues from multiple small burner ports and is ignited. The mixture is typically 6 of air to 1 of gas for Natural Gas with a gas pressure of about 6"wc at the injector jet. The balance of about 4 air to1 gas is obtained from the air in the combustion chamber around the flame. The standard NG tp LPG conversion would be to reduce the jet size and increase the gas pressure to 14"wc. This adjusts the gas flow rate down in the ratio 2.5:1 and the extra pressure compensates for the slightly lower mass flow rate (KE=mv2 and all that). Is this what was done?
5. By what means do you know that the proper combustion air is available. Is this bases on years of experience judging flame picture(appearance), measured gas and air flow rates, or have you collected the products of combustion and analysed them. If the combustion was correct at sea level it is going to be short of air at 8,700ft above sea level.
6. What makes you think you have incomplete combustion. Is the flame depositing soot on the surfaces above the flame?. Does the products of combustion small and possibly irritate the mucous membranes (eyes and nose)? Is the flame soft and yellow with no blue inner cones?
7. If you are observing any of the conditions in 4 above you are in danger of poisoning the chef.
8. Running a Natural Gas burner on LPG at 10"wc will not give a good flame. It will be soft and yellow. Was a conversion kit obtained from the range manufacturer and fitted correctly? The kit would possibly have been as simple as a new jet for each burner and possibly a new pressure regulator for the appliance.
9. If you are getting incomplete combustion then the gas analysis will include: Carbon Dioxide(OK), Water Vapor (OK), Carbon Monoxide(Toxic), and possibly members of the Aldehyde group of compounds, the most common one being Formaldehyde also toxic. The design of you kitchen ventilation system (you do have one, installed to local standards with appropriate interlocks to prevent the operation of the gas appliances if the air flow is not proved to be adequate?) should take care of the CO2 & H2O without any problem and may well remove the CO and Aldehydes as well.

Come back with answeres to the above and more guidance will be forthcoming. Keep in touch.

Gasman