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SAN ANTONIO, TEXAS 

HOUSTON, TEXAS i WASHINGTON, DC i ANN ARBOR, MI 

Date: December 31, 2009 

TO: Chris Laroo 

Environmental Protection Agency 

2000 Traverwood Drive 

Ann Arbor, MI 48105 

SUBJECT: Executive Summary Letter Report for Work Assignment 4-7, EPA Contract EPC-05-018, under SwRI Project 03.14658.07, SwRI Proposal No. 03-54802 

Contract Title: Testing and Analytical Support for Regulation of Motor Vehicles, 

Engines, Fuels, and Fuel Additives 

Assignment Title: PM-PEMS Measurement Allowance Determination 

The United States Environmental Protection Agency (EPA), Engine Manufacturers 

Association (EMA) and California Air Resources Board (CARB) agreed to pursue a data driven 

program to establish a measurement allowance (MA) for in-use particulate matter (PM) testing 

using PM portable emissions measurement systems (PEMS). The PM-PEMS-MA project 

includes three main elements: 

• Laboratory testing using PM-PEMS 

• Monte Carlo simulation using error surfaces generated from laboratory testing to 

determine a measurement allowance 

• Validation of the measurement allowance using in-use PM-PEMS testing 

Three PM-PEMS were accepted by the measurement allowance steering committee 

(MASC) to be included in the PM-PEMS-MA determination project. The MASC also agreed that 

the Particle Proportional Micro Diluter (PPMD) by Sensors and the Transient Particulate Matter 

(TRPM) by Horiba will be used for the official determination and validation of the measurement 

allowance generated. The third instrument, Micro-Soot Sensor (MSS) by AVL, is not a complete 

PM-PEMS and it was always used together with the PPMD on this program, based on an 

agreement reached between Sensors and AVL. The MASC agreed that the MSS will be 

considered as an option to be used for official measurement allowance determination if both the 

PPMD and the TRPM failed to validate. 

Based on the Monte Carlo simulation conducted by SwRI using steady-state and transient 

PM error surfaces, torque and fuel flow error surfaces, and other error surfaces that were 

generated during the gaseous PEMS-MA, the PPMD produced the lowest positive 95th percentile 

measurement allowance of 0.006 g/hp-hr for a threshold level of 0.02 g/hp-hr. Thus, the PPMD 

was chosen for in-use testing by CE-CERT to validate the Monte Carlo predicted measurement 

allowance. 
Mr. Chris Laroo 

Environmental Protection Agency 

December 31, 2009 

Page 2 of 2 

SwRI Project 03.14658.07, SwRI Proposal No. 03-54802 

As of today, validation testing is underway by CE-CERT. Based on the preliminary data 

generated by CE-CERT and sent to SwRI for validation, the PPMD failed the validation criteria 

set by the MASC based on the performance of two PPMD in in-use testing. Testing with the 

third PPMD is underway, and data are under intensive review in preparation for a tentatively 

scheduled Live Meeting on January 14, 2010. 

SwRI is currently working on the preparation of a formal final report on this project. The 

draft final report will be sent to EPA after the validation by CE-CERT is completed and the 

official data are submitted by CE-CERT to SwRI for model validation. 

In order for SwRI to carry on with the project efforts, a new Work Assignment is needed 

for calendar year 2010 to cover the validation analysis and remainder of the write-up of a draft 

final report, and later an official final report after review by the MASC. In addition, the WA will 

need to cover expenses for conducting and attending meetings related to the project by SwRI 

Principal Investigator and other SwRI project team members when necessary. 

Prepared by: Approved by: 

 

Imad A. Khalek, Ph.D. Jeff J. White 

Program Manager Director 

Emissions Chemistry and Particle Science Emissions R&D Department 

Emissions R&D Department Engine, Emissions and Vehicle Research 

 Division 

/tyd U:\Davison\wp\PROJECTS\145658.07 EPA Excecutive Summary Report.docx

cc: Patrick Merritt, Project Manager 

 Sherry Twilligear, Contracts 

 Kathleen Roe, EPA 

 Christine Brunner, EPA 

 

SwRI Project Team: 

 Imad Khalek, Ph.D., Program Manager, Principal Investigator 

 Tom Bougher, Research Engineer, Project Leader 

 Robert Mason, Ph.D., Institute Analyst, Project Co-Investigator/Statistics 

 Janet Buckingham, Staff Analyst, Project Leader/Statistics 

This report shall not be reproduced, except in full, without the written approval of Southwest Research Institute. 

Results and discussion given in this report relate only to the test items described in this report.