Technical Report. 10 th Round Robin Test for Multi-Capillary Pressure Drop Calibration Standards (2014)

Transcription

1 Physical Test Methods Sub-Group Technical Report 10 th Round Robin Test for Multi-Capillary Pressure Drop Calibration Standards (2014) August 2016 Prepared by: James Vincent Cerulean, Milton Keynes, United Kingdom

2 Table of Contents 1. Introduction and Background Experimental Protocol PD Results Overall results Individual laboratory results Comparison between results from the 8 th and 10 th cross-checks Comments on Results... 6 PTM-058-CTR 10 th Round Robin Test - Pressure Drop Calibration August /6

3 1. Introduction and Background The CORESTA Physical Test Methods (PTM) Sub-Group organizes a nominally annual cross-check that is open to the member laboratories that have a calibration laboratory to compare their capability to calibrate standards used in physical test instrumentation. This report covers the results of the pressure drop (PD) standards cross-check to provide a baseline of PD instrument performance across the industry, since this standard type is used in the PD instrumentation of each supplier. Each laboratory is also able to use the result set in internal and external audit assessments. The four participating laboratories in 2014 are listed in Table 1. Table 1: Participating Laboratories Participating laboratories Function Accreditation Borgwaldt KC, Hamburg, Germany Calibration lab & instrumentation supplier ISO 9001 & Cerulean, Milton Keynes, UK Calibration lab & instrumentation supplier ISO 9001 & SODIM, Fleury-les-Aubrais, France Calibration lab & instrumentation supplier ISO 9001 & ZTRI of CNTC, Zhengzhou, PRC Calibration laboratory The laboratory identities are coded in the results presented below. The standards that were circulated between the four laboratories were a set of pressure drop standards at nominally: 200 mmwg (2 kpa) 400 mmwg (4 kpa) 600 mmwg (6 kpa) 800 mmwg (8 kpa) The three instrumentation suppliers use the same physical test piece design and test pieces that are all supplied from a single source, thus only a single set of standards is circulated. 2. Experimental Protocol The protocol involved: acclimatisation of the standards to laboratory conditions testing to the method detailed in ISO 6565:2011 making three PD determinations under repeatability conditions for each standard on two separate days After circulation of the pressure drop calibration standards, the standards were re-checked at the original supplier. PTM-058-CTR 10 th Round Robin Test - Pressure Drop Calibration August /6

4 3. PD Results Overall Results The overall results of all the participants are presented below in Table 2 and as a scatterplot of global coefficient of variation (CoV) across all laboratories against the global mean PD of each test piece in Figure 1. Table 2: PTM PD X-Check 2014 Overall Results Global Mean Std Dev CoV Range Range (mmwg) (mmwg) (%) (mmwg) (% of value) Nom % % Nom % % Nom % % Nom % % Figure 1: Pressure Drop - CoV vs. PD Individual Laboratory Results The mean values obtained by each laboratory for each of the calibration standards are summarized in Table 3. Table 4 shows the deviation from the global mean value for each laboratory and calibration standard. The standard deviation and the coefficient of variation obtained by each laboratory and calibration standard is given in Tables 5 and 6, respectively. A graphical representation of the deviation by laboratory is shown in Figure 2 and by calibration standard in Figure 3. PTM-058-CTR 10 th Round Robin Test - Pressure Drop Calibration August /6

5 Table 3: PTM PD X-Check 2014 Lab Mean by Sample (mmwg) Nom Nom Nom Nom Table 4: PTM PD X-Check Deviation from Sample Mean (%) Nom % 0.01% 0.12% 0.03% Nom % 0.05% 0.15% 0.02% Nom % 0.11% 0.05% 0.06% Nom % 0.13% 0.07% 0.03% Table 5: PTM PD X-Check 2014 Lab Std Deviation by Sample (mmwg) Nom Nom Nom Nom Table 6: PTM PD X-Check 2014 Lab CoV by Sample (%) Nom % 0.07% 0.07% 0.08% Nom % 0.06% 0.09% 0.03% Nom % 0.08% 0.04% 0.03% Nom % 0.08% 0.04% 0.05% PTM-058-CTR 10 th Round Robin Test - Pressure Drop Calibration August /6

6 Figures 2 (left) and 3 (right): Deviation from Global Mean by Lab & by Sample 3.3 Comparison between results from the 8 th and 10 th cross-checks A direct comparison between the results of the 8 th (2011) and 10 th (2014) cross-checks is presented in Figure 4 in terms of the global CoV vs PD for each standard: The 8 th cross-check included only the three instrument suppliers. 4. Comments on Results Figure 4: Pressure Drop CoV vs. PD 2011 & 2014 The PD results conform well with the historical performance and specifically with the results of the 8 th cross-check. It has to be noted, however, that laboratory A measured consistently lower pressure drops for all calibration standards. It is recommened to investigate this deviation further, and to define appropriate actions, if needed. The worst-case offset between laboratories is within 0.3%, which is small compared to the typical value of reproducibility limit exhibited in the annual PTM Proficiency Tests ( ) for PD of products, which is around 6% of the measured value for both cigarettes and filters. Thus instrumental variation deriving from any offset in the calibration of standards is negligible as a cause of variation in the PTM study. PTM-058-CTR 10 th Round Robin Test - Pressure Drop Calibration August /6