A LABVIEW©-Based Mini-SHED System for Permeation Determination of Fuel System Components

In this paper we address the design and performance of a mini-SHED (Sealed Housing Evaporative Determination) system prototype for measurement of hydrocarbon permeation of automotive fuel system components. It is PC-based, and is built around ‘National Instruments’ data acquisition boards and LABVIEW^© software package. It is capable of running the 24-hour diurnal cycle, as well as steady state tests at user-selected temperatures. A flame ionization detector, FID, is used to measure the hydrocarbon emission of the component in the SHED as a function of temperature and/or time. The mini-SHED was tested using propane shot tests and the amount of emission was determined accurately within a +/-4% suggested tolerance. The system has been designed to run unattended once the user has responded to a few prompts. Data is taken and logged once an hour for the diurnal test cycle, and at a user-selected frequency in hours for the steady state test.