API Publ 1673:2009 pdf download
API Publ 1673:2009 pdf download.Compilation of Air Emission Estimating Methods for Petroleum Distribution and Dispensing Facilities.
b) EPA’s Technical Guidance, Stage II Vapor Recovery Systems for Control of Vehicle Refueling Emissions at Gasoline Dispensing Facilities [27], Section 4.4.3, provides guidance for determining in-use control efficiency for Stage Il systems as a function of the population of Stage Il facilities and inspection, maintenance and repair frequencies. Figure 4-15 shows the typical overall efficiency for Stage II to be about 84 % corresponding to annual inspection frequencies and exemptions for stations with throughputs of either less than 2000 gal/mo or less than 10,000 gal/mo.
c) CARB Emission Inventory Factors, Section 4.10, ‘4Gasoline Dispensing Facilities,” May 1999, provides loading, breathing, vehicle refueling, and spillage emission factors for uncontrolled and controlled scenarios at gasoline dispensing facilities.
d) AP-42, Section 5.2.2.3 provides emission factors for controlled and uncontrolled vehicle refueling and for spillage.
Refueling emissions may be controlled by a balance system or a vacuum-assist system. The balance system relies on the pressure created by the fuel entering the vehicle’s tank to force the vapors through the hose and into the dispensing facility’s storage tank. A vacuum-assist system uses a vacuum to pull the vapors from the vehicle’s tank and move them to the storage tank.
Spillage includes the following.
a) Spitback, which occurs when the vehicle’s tank is filled at a faster rate than vapors can escape from the tank. Federal rules limit spitback to 1 gm per vehicle refueling, which is equivalent to 26 mg/L assuming 10 gal per vehicle refueling.
b) Overfills, which can occur when the nozzle shut-off mechanism fails or the operator overrides it.
c) Post-fill drips from nozzles.
Spillage was estimated in several studies noted in the EPA Technical Guidance document, including API 4498 [28]•
These studies measured spills for both uncontrolled and controlled vehicle refueling.
A summary of emission factors for vehicle refueling and spillage is presented in Table 11. A more reliable estimate of emissions would be obtained by using EPA’s MOBILE software, which does account for ORVR controls.
Dispensing gasoline into a motor vehicle’s onboard tank displaces the vapors in the tank, resulting in VOC emissions unless these vapors are captured. The Clean Air Act (CAA) has required two methods for controlling these emissions.
The first approach, called Stage II controls, was required by CAA § 182(b)(3) in the late 1970s for areas classified as moderate, serious, severe, and extreme ozone non-attainment areas. Stage II controls capture gasoline vapors displaced from the motor vehicle’s fuel tank with a flexible bellows that surrounds the gasoline dispensing nozzle, and directs the vapors into the underground gasoline storage tank. Later, these vapors are displaced from the underground tank into the tank truck during filling of the underground tank as a Stage I control. According to EPA’s Office of Transportation and Air Quality, by 2006, 27 states and the District of Columbia implemented Stage II controls in 275 counties. Some states, such as California, require Stage II controls statewide; other states limit Stage II controls to ozone non-attainment areas.
The second approach, called ORVR, was promulgated on April 16, 1994 (59 FR 16262) under CAA § 202(a)(6), and was phased in between 1998 and 2006 as a requirement for new vehicles. ORVR-equipped vehicles have a seal in the tank fill pipe that forms around the dispensing nozzle, and vapors are directed to an activated carbon canister onboard the vehicle. When the vehicle is started, air is pulled through the canister, directing the vapors to the engine where they are burned.
