木屑颗粒规格和办法比拟

固然PFI和ISO尺度在许多方面看起来异常类似，但重要的是要留意二者在规格和参考测试办法中的奥妙差别。

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.

如下迁就规格和办法两方面临PFI尺度和ISO 17225-2尺度停止比拟。

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

请记着，PFI尺度是为北美木屑颗粒行业开辟的，而在大多数情况下，新宣布的ISO尺度异常类似于曩昔的ENplus尺度，这些尺度都是服务于欧洲木屑颗粒市场的。ENplus和CANplus尺度如今参考品质品级规格A1、A2和B级，正如ISO 17225-2中所述的，但临盆商重要临盆“A1级”。

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.” 

别的，固然PFI尺度包含高档、尺度和通用品级尺度，但绝大多数临盆者制作高档品级。本文将PFI的高档品级与ISO 17225-2 A1品级的请求停止比拟。
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尺度容许40-48磅/立方英尺的体积密度规模，而ISO 17225-2触及600-750公斤（kg）/每立方米规模，（37.5至46.8磅/立方英尺）。测试办法的分歧的地方在于它们应用分歧尺寸的容器、分歧的紧缩办法和分歧的浇注高度。除这些差别以外，这两种办法具有大水平的可变性，这取决于小我技巧。只管存在这些差别和固有的可变性，这两种办法彷佛发生类似的成果。
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的直径规模是0.230-0.285英寸（5.84-7.24毫米（妹妹）），这是基于美国临盆商重要应用四分之一英寸模具和一些稍大的模具。ISO 17225-2请求临盆者应用6或8妹妹，每一个容许±1妹妹的公役，即容许5至9妹妹（0.197至0.354英寸）规模，假设6妹妹直径最接近惯例的四分之一英寸（6.35妹妹 ）模具尺寸，则预期临盆者将应用6妹妹。不肯定8妹妹直径产物会若何影响炉具机能。两种测试办法的平均值的直径都是应用卡尺来丈量的。
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办法遵守滚筒办法，此中形状尺寸为12英寸×12英寸×5.5英寸（305妹妹×305妹妹×140妹妹）。ISO办法应用类似略小的滚筒（300妹妹×300妹妹×120妹妹）。没有发明尺寸的差别招致测试成果的明显差别。
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将细粒界说为可经由过程八分之一英寸筛网（3.175-妹妹方孔）的资料。对付ISO 17225-2，细粒界说为经由过程3.15 妹妹圆孔筛网的资料。纵然尺寸3.175和3.15看起来类似，由于PFI的是方形孔，而且ISO的是圆形孔，孔径尺寸的差别约30％。是以，PFI测试将较大部分的资料分类为细粒，只管对ISO具有可比的细粒请求（对付袋装资料，二者的参考细度限值为0.5％）。别的，当经由过程PFI办法测试时，招致耐久性测试成果低落约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.

对付灰分含量，PFI和ISO应用相称类似的灰化温度，PFI为580-600摄氏度，ISO为550℃。我没有看到这些温度之间的明显差别，我觉得这两种办法供给可比的成果。PFI灰分限定为1％，ISO 17225-2灰分限定为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.

对于长度，PFI不容许跨越1％擅长1.5英寸（38.1妹妹），而ISO不容许跨越1％擅长40妹妹（1.57英寸），而且没有擅长45妹妹的颗粒。当比拟38.1妹妹 和40妹妹时，PFI测试更严厉，然则，ISO尺度划定不容许颗粒跨越45妹妹，这方面来讲ISO更严厉。对付测试办法，PFI测试更完全，由于在2.5磅（1.134克）的最小样品尺寸上停止测试，而ISO测试在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应用热量计办法来肯定热值，而且两个参考测试成果间接来自仪器的。然则，对付ISO 17225-2，能量含量的划定限制表现净热值，也称为较低热值。 对付PFI，热值表现为总热值或更高的热值（HHV）。这些参数不克不及间接比拟。ISO划定A1品级颗粒必要大于或即是4.6千瓦时/ kg（相称于7119Btu /磅）。PFI尺度请求临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办法重要用氯离子色谱法作为重要办法，但容许几种间接阐发技巧。PFI列出了几种接收的办法。它们的检测规模和所需的仪器都分歧。PFI对氯的限值为300毫克（mg）/每公斤（kg），ISO请求为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今朝没有在其尺度中列出金属限定，而且没有指定测试办法。ISO对八种金属有限定，并参考了一种用于阐发金属的ISO测试办法。ISO 17225-2还列出了PFI尺度中没有的几个附加参数的请求，包含变形温度，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尺度在许多方面看起来异常类似，但重要的是要留意二者在规格和参考测试办法中的奥妙差别。

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.