(II) Vapor Recovery in Vermont
In August of 1996, the Air Quality & Climate Division adopted rule 5-253.7 (Stage II Vapor Recovery Controls at
Gasoline Dispensing Facilities) to help prevent the release of harmful
gasoline vapors to Vermont's ambient air. The requirements of the rule
apply to any gas station with an annual gasoline
throughput of 400,000 gallons or more.
Not only do gasoline vapors contain several
known and suspected human carcinogens, there are also several
noncarcinogenic hazardous air contaminants in gasoline vapor. Many of
those same toxic chemicals are ground-level ozone precursors as well i.e.,
they are the chemicals that under the right atmospheric conditions (the
presence of sunlight and warm, summer-time temperatures) react to form
ground-level ozone, a strong lung and eye irritant known to trigger
The Vermont Air Quality & Climate Division
encourages you to choose gasoline stations with vapor recovery nozzles.
These gasoline nozzles have prevented several thousand tons of volatile
organic compounds from evaporating into Vermont's air during the past several years.
Please remember not to top off your gas tank. "Topping
off" or continuing to fill your tank after the pump clicks off may
result in gasoline spillage or block the vapor recovery system, rendering
it ineffective. Generally, when the pump shuts off, your tank is full and
topping-off adds only a few more ounces.
How to Identify a Gas
Station with Stage II Vapor Recovery
In most cases, it should be evident
whether a gasoline station has Stage II Vapor Recovery in place.
Many stations in compliance with the rule have this blue
decal posted at the pump. Often the decals are affixed
visibly to the pump
near the hook. Also, many vapor recovery nozzles have a "Do
not top off" warning printed on the back of the nozzle.
Types of Stage II
Vapor Recovery Nozzles
There are three basic nozzle
types a person might see at gasoline stations in Vermont.
- Standard, non-Stage II nozzles
- Vapor Balance Recovery Nozzles and
- Vacuum-assist Vapor
Standard nozzles should be
found only at gasoline stations (and other gasoline
distribution facilities) with a throughput less than 400,000
gallons per year. On the surface, a typical standard
nozzle looks very similar to a vacuum assist nozzle but it does not capture gasoline vapors.
Vapor Recovery - Balance Nozzles
system nozzles look distinctly different than standard
nozzles. The balance nozzles have a bellows-like rubber boot that creates a seal over the vehicle's
gas tank opening. Balance systems use the slight amount of
pressure that is created in a vehicle fuel tank by the incoming
liquid gasoline and the slight vacuum created in the
underground storage tank by the departing liquid gasoline
to pull the vapors out of the vehicle tank and transfer them
to the underground storage tank. Balance systems
require the tight seal of a boot on the nozzle with the
vehicle fill-pipe so that the vapors generated during fueling
are captured by the nozzle and cannot escape to the
atmosphere. The rubber boot must be compressed to activate the
Vapor Recovery - Vacuum-assist Nozzles
nozzles are virtually indistinguishable from nonvapor
recovery nozzles. However, many of
them have holes
near the tip of the nozzle which permits the vapors to be
drawn back into the underground gasoline storage tank. The
nozzles may have a small rubber boot or splash guard as
Vacuum-assist systems utilize
some type of vacuum producing device (e.g. vapor pump) to enable
the nozzle to capture vapors from the vehicle fuel tank. This
design allows vapors to be captured without the need
for a tight seal by the nozzle boot.
For further information regarding
the Stage II regulation in Vermont please click here.
To see subchapter 5-253.7 of the Vermont Air Quality & Climate Regulations click here.
to Air Toxics Program Page
Last Updated: 1/22/03