API Publ 1645-2002 pdf download.Stage II Vapor Recovery System Operations & System Installation Costs.
Given the role that gasoline vapors (in the form of volatile organic compounds [VOCs]) play in the formation of ozone, retail gasoline outlets (RGOs) become a high-proÞle target in efforts to attain the ozone standard. As an obvious source of VOC emissions, RGOs generally receive high priority for fur- ther controls in metropolitan areas that have not met ozone attainment standards. The total emissions controlled and the costs associated with the installation and maintenance of Stage II vapor controls are not always adequately compared to other air pollution control strategies, especially those associated with mobile tailpipe emissions (on-road and off-road) that may be less obvious but more cost effective. In December 1988, API published the API Survey of Actual Stage II Implementation Costs in the St. Louis Metro- politan Area. At the time, the average cost of installing Stage II on a per-nozzle basis was $1,660. In the 14 years since the publication was issued, new generations of Stage II equip- ment with improvements and variations have been introduced and put into service. For example, the “vapor balance” system nozzle is now lighter, easier to use and more durable. A new type of passive vacuum assist Stage II system has also been developed and has become prevalent. Up-to-date average costs associated with installing Stage II vapor recovery systems at typical RGOs are provided in this research. Equipment and installation costs for the more com- monly used Stage II vapor recovery systems are also identi- Þed. SigniÞcant effort was made to ensure that the Stage II cost analyses in this research reßect credible, current averages. Cost data was derived from a survey of API member com- panies and interviews with selected Stage II installation and maintenance experts. Although information was solicited on all types of vapor recovery systems, information on active vacuum assist systems was not received. Other alternative sources were consulted for this information.
Passive vacuum assist systems may be distinguished from active vacuum assist systems by their dispenser-based approach to vapor recovery. Passive vac-assist stations use ßow controls at the dispenser to return vapor to the gasoline storage tank, whereas active vac-assist systems use a central vacuum unit to recover vapor from the entire system to the tank, pro- cessing excess vapor by incineration or by other means. The earliest version of passive vac-assist systems relied on reciprocal pumps within each dispenser housing that inher- ently varies the speed of vapor recovery based on product ßow through the dispenser. The greater the product ßow, the more gasoline vapor is recovered. Newer versions use electri- cal pumps to return recovered vapor to the gasoline tank, where the amount of vacuum generated to recover vapors is based on the gasoline ßow rate detected electronically through the dispenser meter. As the basic principal behind the passive vac-assist system is to recover vapors equivalent to those generated during the refueling process, passive vac-assist systems do not employ vapor processors. For this reason, the ratio of product dis- pensed to the vapor recovered is important to the effective- ness of the system. Consequently, some regulators have placed increased emphasis on A/L testing to ensure that passive vac-assist sys- tems remain within certiÞed 95% effectiveness levels. A few agencies demand compliance testing at greater than the annual frequency outlined in the California Air Resources Board (CARB) Executive Orders certifying the passive vac- assist systems. This more frequent testing increases the annual maintenance costs borne by those operating passive vac-assist equipment. A signiÞcant number of Òactive vacuumÓ processor-type systems are in use. These systems differ from the Òpassive vacuumÓ assist systems chießy in the deployment of a single- unit vacuum generator applying a vacuum to the whole vapor recovery system.