SAE ARP6481A

This SAE Aerospace Recommended Practice (ARP) details the recommended process for correcting measured non-volatile particulate matter (nvPM) mass and number data for particle losses in the sampling and measurement system specified in ARP6320B. This technique is only recommended for conditions where both nvPM mass and number concentration measurements are in the valid measurement ranges of the instruments that are discussed in the tool limitations section. This ARP also supplies an Excel software tool with documentation to automate the process. The body of this ARP details the recommended calculation method, uncertainties, and limitations of the system loss correction factors. It explains, in detail, the required inputs and outputs from the supplied Excel software tool (developed on Windows 7, Excel 2016). Also included are: The Excel correction tools (refer to Attachments I and V). Installation instructions for a Windows-based computer (refer to Attachment II). A user technical manual (refer to Attachment III) describing functions used within the tool and optional Excel add-in (refer to Attachment VI). Multiple sample test cases (refer to Attachment IV). The Excel tools are intended to do the full calculation described in AIR6504. This ARP provides documentation for the Excel spreadsheet system loss tool lite version (nvPM System Loss Tool _Lite v2_6 Release.xlsm). The difference between the full tool and lite tool is described in Appendix C. Attachments III and VI are also described in Appendix C. If the user has produced their own software for the AIR6504 correction, comparison of results from this tool may be used to verify that software. This ARP does not contain the full description of the sampling and measurement system described in ARP6320B. The correction technique is only briefly discussed in this ARP. More detailed information is provided in AIR6504. At this time, nvPM size measurement is not within the scope of this ARP, but it may be considered in the future. This SAE Aerospace Recommended Practice (ARP) revision provides updates to the system Section 2 particle loss. Minor clarifications or editorial changes throughout the document are also included. This revision is limited in scope. There is an updated definition of the T1 location from the Diluter1 inlet to Splitter1 metal. This is to clarify the Section 1 thermophoretic loss calculation. An updated estimate of Diluter1 losses and any Section 2 thermophoretic losses using a “thermophoretic loss” from Splitter1 to the Diluter1 outlet is prescribed using the new definition of T1 and the temperature at the exit of the Diluter1 T2 (assumed to be 333.15 K). This estimate is expected to be an interim revision while further work is performed to verify Section 2 particle loss and improve uncertainty. To help this work, optional Section 2 measured sampling system temperatures near the Diluter1 inlet, which are measured in some specific system designs, are reported as per ARP6320B. Minor wording changes to clarify some areas of the document are included. Minor wording changes and variable renaming to clarify the temperatures used in VPR penetration calculation in the Excel spreadsheet system loss calculator tool are included.