One of the least known safety devices associated with the use of propane gas is a propane gas detector. A propane gas detector works similarly to a smoke detector. A gas detector will detect the presence of escaped gas and will send an alarm loud enough to alert those inside a home to evacuate. The propane gas industry for years has promoted the notion that if there is a gas leak in a home the occupants will be immediately warned by the odor of gas. Not true! The odor of propane gas is completely insufficient to serve as a warning for a wide variety of reasons. The odorant added to propane gas is a chemical particularly susceptible to fading or dissipating to such a low level that it is not capable of being detected by the human nose.
Propane gas while having utility as a fuel source for many appliances including the appliances in a home it also has very dangerous characteristics. In its natural state, propane or LP-Gas is invisible, colorless, odorless, tasteless and heavier than air. That is why a chemical odorant is added to the propane.
Propane is at least twice as explosive as natural gas, and burns twice as hot. A person who uses propane in his/her home is five to ten times more likely to be involved in a propane explosion than natural gas explosion.
There are physical reasons why the odor warning is defective. Among them is the fact that the odor will not awaken a sleeping person. Furthermore, if leaked gas accumulates in a basement it is likely to remain there. Persons who are on the first floor would not be warned because the gas must actually come into contact with your nose in order to be warned.
Through the process of oxidation, adsorption and absorption the odor can be reduced or eliminated, and thus incapable of warning an effected person. Oxidation occurs when the ethyl mercaptan comes into contact with rust which can occur in storage tanks and gas lines. Contact with concrete walls, masonry, soil, building blocks, furniture, fabric, drapes and other materials likewise can strip the odorant from the propane thereby reducing or eliminating the odor. The odor stays with the propane. This means that unless the consumer’s nose is in the concentration of gas there is no possibility of being warned by odor alone.
Many propane appliances especially in the Midwest are located in basements. Basements are a particularly dangerous place to have propane appliances because of the heavier than air characteristic of propane. If propane gas leaks into a basement, adsorption occurs which will reduce or completely eliminated the odor warning. However, equally dangerous is the fact that unless a person journeys into the basement for some reason, no occupant of a home on the first floor or above will be warned. Indeed propane gas can leak in an adjacent room to an occupant of a home and the occupant still not be warned. An occupant can even walk into a room where dangerous concentrations of propane gas exist and not be warned. The reason for this is propane is heavier than air and the leak can be at floor level. Thus, a person standing upright would not be warned of propane at floor level.
The human nose is a poor gas detector. The reason for this is that there are physiological limitations to using an odor warning including olfactory fatigue. By this method one can be exposed to the odorant before it reaches a detectable level and by the time the odorant is detectable the nose has become desensitized such that it cannot detect the odor.
Odor masking can occur. The smell common in basements or cooking odors are known to cover up or mask the odor warning. The strength of smell is a factor, as well as colds, age, sex, smoking and distractions all factor into whether a person will be warned by the odor warning system. The distraction a person is under plays a significant role concerning the effectiveness of the odor warning. If a person is in a directed mode attempting to smell for gas especially at floor level and told to smell for gas there is a far greater chance the occupant or consumer will be able to detect escaped propane as compared to the average occupant who does not expect that propane gas has escaped.
Serviceman gas detectors have been used for many years by the propane gas industry for the protection of gas employees. These are highly reliable instruments and work on the same principle as residential gas detectors.
The only reliable way to warn a person is to install one or more gas detectors. You should ask your gas delivery man to provide you with a gas detector. Alternatively they can be purchased for any reasonable sum at any hardware store. It again it is the only protection for you and your family.
Donald G. Beattie