AUTOBLEND Complex Gas Mixture Generator

AUTOBLEND™ Complex Mixture Generator

OVERVIEW

The AUTOBLEND™ instrument is designed to create flowing complex gas mixtures for:

Evaluating sensor response,
Validating analytical methods,
Testing catalytic systems for sensitivity to contaminants,
Biological testing for effects of inhaled vapors,
Research and development,
and much more.

Fig. 1 - AUTOBLEND™ Instrument
(click here for a larger sideview image; 6 mb size; high quality)
(click here for a large frontview image; 4 mb size; high quality)

The system features six independently-controlled permeation ovens. The base gas mixture created in each oven can contain up to eight different analyte components so that a test atmosphere can be spiked with up to 48 components simultaneously.

A variable portion of each base gas mixture is added to a main dilution flow to create a primary mixture with variable concentration ratios. Two optional dynamic headspace saturation modules can be added (as shown in bottom cabinet) to allow the addition of vapors from potential transient interfering compounds such as cleaning solutions, fuels or paints. A secondary dilution feature provides a large dynamic concentration range. The resulting test atmosphere can be supplied either dry or at variable humidity levels.

AUTOBLEND™ SOFTWARE

Designed for use with the AUTOBLEND™ instrument, the Microsoft® Windows® 2000/XP-based AUTOBLEND™ software:

Manages an inventory of methods, permeation tubes and headspace mixtures.
Analyzes the feasibility of creating a specified mixture.
Calculates the setpoint data required to adjust the system to achieve the mixture.
Dynamically maintains the mixture under changing conditions.
Logs operating data and test mixture results.

Fig. 2 - Virtual Instrument of the AutoBlend™ System
(click here for a larger image)

FEATURES

Permeation Tube and Headspace Inventory Management
The AUTOBLEND™ software contains a database of the user's permeation tube and optional headspace inventory including tube ID and serial number, compound name, emission rate data, temperature alarm criteria, and expiration date (see Fig 3). As the expiration date approaches, the tube is highlighted to warn the user to reorder or recertify.

The following figure shows an example inventory of permeation tubes.

Fig. 3 - Permeation Tube Inventory
(click here for a larger image)

Method Inventory Management
As specific complex gas mixture sets are defined, the details of the components (permeation tubes and headspaces) and required concentrations of up to 20 span points are saved as a method. These methods are saved in an inventory for easy recall and duplication of the mixture at a later date.

Data Logging
During a method run, the AUTOBLEND™ software periodically logs generated concentrations for each point in the method (see Fig. 4) and logs measured values of all operating parameters. Should an unexpected test result occur, the historical data can be checked to verify the mixture and operating conditions such as oven temperature, flow rates, pressures and so forth.

Fig. 4 - Data Log
(click here for a larger image)

Scenario Analysis
The AUTOBLEND™ software set includes a "Scenario Analyzer" CD that allows the user to establish offline the feasibility of achieving a desired mixture. Given desired concentrations, the AUTOBLEND™ software tests the possibility of creating the mixture from specific permeation tubes and headspaces under specific operating conditions. This feedback is invaluable in creating a workable method and can be a major time saver.

System Monitoring
AUTOBLEND™ system functions are monitored in the software and out-of-specification values are reported. For example, the software warns of "over temperature" conditions in the permeation ovens, impossible flow settings, out of range temperature setpoints (for the installed permeation tubes), etc.

Enhanced Functionality
The actual permeation rate from each tube varies with temperature. The AUTOBLEND™ software can correct to actual or estimated temperature depending on supporting data available for the tube. When multi-point certification data is available, the correction is exact at the temperature of the defined certification point, and estimated with a linear or log-linear algorithm when at an uncertified temperature point. Even for a single-point certification, an enhanced estimation algorithm is applied for the case in which the user elects to use a temperature other than the certification temperature.

System Requirements
The AUTOBLEND™ software runs on Microsoft® Windows®2000 or XP with an RS-232 serial port (or USB-to-RS232 adapter) connected to the AUTOBLEND™ Complex Gas Mixture Generator. The AUTOBLEND™ Inventory and data logs are stored in a Microsoft® Access database (Microsoft® Access is not required to be installed). The software requires about 15 MB of hard disk space plus extra storage space for the database.