ECONOMICS OF ODORIZATION
must supply natural gas which is odorized within certain limits. Too little
odorization may make the presence of the fuel undetectable to some, thereby
creating a potentially dangerous situation. Too much of same may not be
particularly hazardous [except by offending olfactory sensors], but it
can be costly to the utilities. The excess odorant will make otherwise
imperceptible leaks very perceptible. It will propagate within a closed
environment [such as a house]. The result is a veritable swarm of technicians
following the trail of an overodorized pipeline through user neighborhoods.
They respond to customer complaints of gas leaks which are really of no
consequence. On top of that, they have expended far more odorant than
is necessary and odorant is not cheap.
utilities opt to substantially overodorize to eliminate potential liabilities.
Typical installations utilize metering pumps which inject odorant into
natural gas pipelines. At best, on their own, these devices are capable
of accuracies on the order of ±10% [this is assuming that they
are working properly and that the odorant supply hasn't run dry].
this typical system is effected by a technician, on site. The technician
periodically checks and adjusts the metering pump pneumatic timer so that
the pump output corresponds to the gas flow indicator reading. In parts
of the country that are subject to rapid weather changes, it is not uncommon
for such a technician to get a call in the middle of the night to rush
to the site to make an adjustment for a sudden cold snap. The addition
of a couple of off-the-shelf components, would allow these technicians
to sleep better. They would normally only be required to perform routine
A Microflowmeter (as manufactured by DEA Engineering Company - see www.deaengineering.com)
is used to provide positive feedback to the control system that odorant
is, indeed, being pumped to the pipeline. This overcomes the previously
mentioned potential failures of improper metering pump function and depletion
of the odorant supply.
valve replaces the pneumatic timer which is normally part of the injection
(such as a PLC which is available from many Industrial Control manufacturers)
not only controls the system, but can trigger alarms, transmit information
and even shut down the pipeline as warranted.
typically have a payback on the order of less than a year if a utility
reduced its odorant injection to minimum levels. Some additional margin
would, no doubt, be judicious. Perhaps of far greater value than whatever
savings are achieved, is the comfort such a system provides in this litigious
result is more efficient operation, significant reduction in odorant injection
costs and a substantial increase in reliability and safety.