固然PFI和ISO尺度在許多方面看起來異常類似，但重要的是要留意二者在規(guī)格和參考測試辦法中的奧妙差別。

While the PFI and ISO standards seem very similar in many ways, it is important to note the often subtle differences in the specifications and the referenced test methods, as PFI and ISO are not always comparable.

如下遷就規(guī)格和辦法兩方面臨PFI尺度和ISO 17225-2尺度停止比擬。

Recently, I was asked to compare the methods and specifications referenced in the PFI standards with the seemingly similar ISO 17225-2 standard. 

請記著，PFI尺度是為北美木屑顆粒行業(yè)開辟的，而在大多數(shù)情況下，新宣布的ISO尺度異常類似于曩昔的ENplus尺度，這些尺度都是服務(wù)于歐洲木屑顆粒市場的。ENplus和CANplus尺度如今參考品質(zhì)品級規(guī)格A1、A2和B級，正如ISO 17225-2中所述的，但臨盆商重要臨盆“A1級”。

Bear in mind that the PFI standards were developed for the North American wood pellet industry, while in most cases, the newly published ISO standards closely resemble former EN standards, which were written for the European markets. ENplus and CANplus now reference the specifications for quality classes A1, A2 and B, as outlined in ISO 17225-2, but producers primarily manufacture “A1 grade.” 

別的，固然PFI尺度包含高檔、尺度和通用品級尺度，但絕大多數(shù)臨盆者制作高檔品級。本文將PFI的高檔品級與ISO 17225-2 A1品級的請求停止比擬。
Also, while the PFI standards provide criteria for premium, standard and utility grades, the vast majority of producers manufacture premium grade. This exercise compares the requirements of PFI’s premium grade with ISO 17225-2 A1 grade.

PFI尺度容許40-48磅/立方英尺的體積密度規(guī)模，而ISO 17225-2觸及600-750公斤（kg）/每立方米規(guī)模，（37.5至46.8磅/立方英尺）。測試辦法的分歧的地方在于它們應(yīng)用分歧尺寸的容器、分歧的緊縮辦法和分歧的澆注高度。除這些差別以外，這兩種辦法具有大水平的可變性，這取決于小我技巧。只管存在這些差別和固有的可變性，這兩種辦法彷佛發(fā)生類似的成果。
PFI specifications allow a bulk density range of 40 to 48 pounds per cubic foot, while ISO 17225-2 references a range of 600 to 750 kilograms (kg) per cubic meter. (37.5 to 46.8 pounds per cubic foot). The test methods are different in that they use different-sized containers, different methods of compaction and different pour heights. In addition to these differences, both methods inherently have a large degree of variability as a result of the test being dependent on individual technique. Despite all of these differences and the inherent variability, the two methods do seem to generate similar results.

PFI的直徑規(guī)模是0.230-0.285英寸（5.84-7.24毫米（妹妹）），這是基于美國臨盆商重要應(yīng)用四分之一英寸模具和一些稍大的模具。ISO 17225-2請求臨盆者應(yīng)用6或8妹妹，每一個容許±1妹妹的公役，即容許5至9妹妹（0.197至0.354英寸）規(guī)模，假設(shè)6妹妹直徑最接近慣例的四分之一英寸（6.35妹妹 ）模具尺寸，則預(yù)期臨盆者將應(yīng)用6妹妹。不肯定8妹妹直徑產(chǎn)物會若何影響爐具機能。兩種測試辦法的平均值的直徑都是應(yīng)用卡尺來丈量的。
PFI’s diameter range is 0.230 to 0.285 inches (5.84 to 7.24 millimeters (妹妹). This is with the understanding that U.S. producers predominantly use a one-quarter-inch die and some slightly larger die sizes. ISO 17225-2 requires that producers declare 6 or 8 妹妹, each with a tolerance plus or minus 1 妹妹, allowing for a potential range of 5 to 9 妹妹 (0.197 to 0.354 inches).  Given that the 6 妹妹 diameter most closely resembles the customary one-quarter-inch (6.35 妹妹) die size, it would be expected that producers would declare 6 妹妹. It is uncertain as to how the 8 妹妹 diameter product would affect stove performance. Both test methods use calipers to measure the diameter where the mean value is reported.

至于耐久性，PFI辦法遵守滾筒辦法，此中形狀尺寸為12英寸×12英寸×5.5英寸（305妹妹×305妹妹×140妹妹）。ISO辦法應(yīng)用類似略小的滾筒（300妹妹×300妹妹×120妹妹）。沒有發(fā)明尺寸的差別招致測試成果的明顯差別。
For durability, the PFI method follows the tumbler method, where the chamber dimensions are 12 inches by 12 inches by 5.5 inches (305 妹妹 by 305 妹妹 by 140 妹妹). The ISO method uses a similar tumbler that is just slightly smaller (300 妹妹 by 300 妹妹 by 120 妹妹). I have not found the differences in the box dimensions to cause a significant difference in test results, but in theory, the slightly larger box could suggest a slightly more aggressive test for the PFI method.

PFI將細粒界說為可經(jīng)由過程八分之一英寸篩網(wǎng)（3.175-妹妹方孔）的資料。對付ISO 17225-2，細粒界說為經(jīng)由過程3.15 妹妹圓孔篩網(wǎng)的資料?？v然尺寸3.175和3.15看起來類似，由于PFI的是方形孔，而且ISO的是圓形孔，孔徑尺寸的差別約30％。是以，PFI測試將較大部分的資料分類為細粒，只管對ISO具有可比的細粒請求（對付袋裝資料，二者的參考細度限值為0.5％）。別的，當經(jīng)由過程PFI辦法測試時，招致耐久性測試成果低落約0.7。
PFI defines fines as material passing through a one-eighth-inch wire mesh screen (3.175-妹妹 square hole). For ISO 17225-2, fines are defined as material passing through a 3.15-妹妹 round hole screen. Even though the screen dimensions 3.175 and 3.15 seem similar, because the PFI screen has square holes and the ISO screen has round holes, the difference in aperture size is about 30 percent. As such, the PFI test classifies a larger portion of the material as fines making it harder to pass the PFI fines test, despite having a comparable fines requirement for ISO (both reference a fines limit of 0.5 percent for bagged material). In addition, this causes the durability test result to be approximately 0.7 lower when tested via the PFI method.

對付灰分含量，PFI和ISO應(yīng)用相稱類似的灰化溫度，PFI為580-600攝氏度，ISO為550℃。我沒有看到這些溫度之間的明顯差別，我覺得這兩種辦法供給可比的成果。PFI灰分限定為1％，ISO 17225-2灰分限定為0.7％。
For ash content, both PFI and ISO use fairly similar temperatures for ashing, 580 to 600 degrees Celsius for PFI, and 550 C for ISO. I have not seen a significant difference between these temperatures, and I consider these two methods to deliver comparable results. The PFI limit for ash is 1 percent, and the ISO 17225-2 limit for ash is 0.7 percent.

對于長度，PFI不容許跨越1％擅長1.5英寸（38.1妹妹），而ISO不容許跨越1％擅長40妹妹（1.57英寸），而且沒有擅長45妹妹的顆粒。當比擬38.1妹妹 和40妹妹時，PFI測試更嚴厲，然則，ISO尺度劃定不容許顆粒跨越45妹妹，這方面來講ISO更嚴厲。對付測試辦法，PFI測試更完全，由于在2.5磅（1.134克）的最小樣品尺寸上停止測試，而ISO測試在30至40克下停止。
Regarding length, PFI does not allow more than 1 percent to be longer than 1.5 inches (38.1 妹妹), while ISO does not allow more than 1 percent to be longer than 40 妹妹 (1.57 inches) and no pellets longer than 45 妹妹. When comparing 38.1 妹妹 40 妹妹, the PFI test is more rigorous, however, the ISO specification that no pellet can be longer than 45 妹妹 can make the ISO specifications more rigorous. For the test method, the PFI test is more thorough, in that the test is performed on a minimum sample size of 2.5 pounds (1,134 grams) while the ISO test is performed on 30 to 40 grams.

PFI和ISO應(yīng)用熱量計辦法來肯定熱值，而且兩個參考測試成果間接來自儀器的。然則，對付ISO 17225-2，能量含量的劃定限制表現(xiàn)凈熱值，也稱為較低熱值。 對付PFI，熱值表現(xiàn)為總熱值或更高的熱值（HHV）。這些參數(shù)不克不及間接比擬。ISO劃定A1品級顆粒必要大于或即是4.6千瓦時/ kg（相稱于7119Btu /磅）。PFI尺度請求臨盆者地下收到的最低HHV。
PFI and ISO use calorimeter methods for determining the heating value, and both referenced tests yield comparable results direct from the instrument. For ISO 17225-2, however, the specified limit for energy content is expressed as the net calorific value, also referred to as lower heating value. For PFI, the heating value is expressed as the gross calorific value, or higher heating value (HHV). These parameters are not directly comparable. ISO provides a limit that the A1 pellets need to be greater than or equal to 4.6 kilowatt-hour per kg (equivalent to 7119 Btu per pound). The PFI Standard requires the producer to disclose the minimum HHV as-received.

ISO辦法重要用氯離子色譜法作為重要辦法，但容許幾種間接闡發(fā)技巧。PFI列出了幾種接收的辦法。它們的檢測規(guī)模和所需的儀器都分歧。PFI對氯的限值為300毫克（mg）/每公斤（kg），ISO請求為200mg/kg。
The ISO method for chlorine references ion chromatography as the primary method, but has language for allowing several direct analysis techniques. PFI lists several accepted methods. All differ in their detection limits and instrumentation required. PFI’s limit for chlorine is 300 milligrams (mg), per kilogram (kg) and the ISO requirement is 200 mg per kg.

PFI今朝沒有在其尺度中列出金屬限定，而且沒有指定測試辦法。ISO對八種金屬有限定，并參考了一種用于闡發(fā)金屬的ISO測試辦法。ISO 17225-2還列出了PFI尺度中沒有的幾個附加參數(shù)的請求，包含變形溫度，氮和硫。
PFI does not currently have metals listed in its standard, and no test method is specified. ISO has limits for eight metals, and references an ISO test method for analyzing metals. ISO 17225-2 also lists requirements for several additional parameters not included in the PFI standards, including deformation temperature, nitrogen and sulfur.  

固然PFI和ISO尺度在許多方面看起來異常類似，但重要的是要留意二者在規(guī)格和參考測試辦法中的奧妙差別。

While the PFI and ISO standards seem very similar in many ways, it is important to note the often subtle differences in the specifications and the referenced test methods, as PFI and ISO are not always comparable.