Propane is used as a fuel for many residential, commercial, and industrial applications. Propane is an odorless gas. For most applications, odorant is added to propane so that it can be detected by smell. Sufficient odorant is supposed to be added to propane so that it can be detected at 1/5 the lower explosion limit. Therefore, if the propane is sufficiently odorized, it should be detectable by most people at a concentration of only 1/5 the concentration required for combustion or an explosion. There are several factors that can affect an individual¨s ability to detect the odorant in propane. These include age, health, and competing odors. Furthermore, odorant has been known to fade in new steel piping and tanks and in clay rich soils.
Propane is stored in cylinders and tanks as a liquid. As long as there is some liquid in the container, at steady-state conditions, the pressure in the propane container is a function only of the temperature of the liquid in the container. The pressure is not a function of the amount of liquid in the container.
Propane is a gas at ambient temperatures and pressure. At atmospheric pressure, propane cannot exist as a liquid above about -44 degrees F.
Propane gas has a specific gravity of about 1.5 Therefore, it is about 1.5 times as heavy as air. Because it is heavier than air, in a calm atmosphere propane will have a tendency to occupy lower elevations. However, propane will diffuse in air and air currents can have a significant effect on the distribution of propane within the living space.
Propane expands approximately 270 times in going from liquid to gas.
Applicable Codes are - Liquefied Petroleum Gas Code, and - National Fuel Gas Code.
Failure analysis of propane fires or explosions may involve any, or all, of 4 major areas: the cylinders or tanks, the regulators, the piping, and the appliances. Some items to consider follow:
Cylinders or Tanks: NFPA 58 has regulations on how close various size cylinders and tanks can be to buildings, and openings to the buildings. Propane cylinders must be periodically requalified to ensure that they can safely carry liquid propane.
Regulators: Testing on regulators includes checking delivery pressure and lockup pressure (pressure with no flow). Another test is to check that under lockup conditions the delivery pressure does not continue to rise.
Piping: Any connection in the piping could be a potential leak source. Unless there is good reason for the contrary, all connections should be leak checked before they are disassembled.
Appliances: The orifices and the regulator set pressure on the appliance must match the fuel gas being used.
All testing should be well documented and all involved parties should be notified before any testing is done.
Our Associates:
We have considerable experience in forensic analysis, and provide expert witness services, in fuel gas fire and explosion accidents. Experience in fuel gas cases includes propane and natural gas explosions and fires, and acetylene fires. Iinvestigations included the evaluation of appliances, piping, valving, and containers, and leak and performance testing.
Our Associates have conducted failure analysis in chemical plant fires, explosions, and other accidents. Our Associates have also investigated carbon monoxide incidents.
We assist the insurance and legal professions in forensic analysis of fuel gas fires and explosions, chemical plant fires and explosions, electrical fires, and carbon monoxide incidents resulting in property damage, bodily injury, litigation, and subrogation claims. We provide expert technical failure analysis services to both plaintiffs and defendants, and insurance professionals.
