In aggregate applications, sample material is frequently collected manually. While this does provide material to the laboratory for analysis, the methods used for manual sample collection are often not the safest, most accurate or most efficient means to collect a sample.
Manual sample collection methods
Let’s take a look at a few of the more common methods of manual sampling.
Stopped belt sampling
Of the many manual sample collection methods available, the stopped belt sample is the most accurate – though probably the least efficient. 停止带取样允许在传送带上的一个区域内的所有材料颗粒的完全去除, which is physically bounded by a set of dividers.
Unfortunately, 这还要求在收集每个增量时停止传送带(并遵循适当的锁定/标记程序)-这种情况不太可能受到操作人员或工厂管理人员的欢迎.
A stopped belt sample is, however, a good reference for discussing what an ideal sample increment should be, particularly since potential dynamic problems are not present, 当样品增量被移除时，分配器(切割器)和传送带都没有移动. In fact, 大多数偏置测试涉及在正常工作条件下收集的样品与停止带参考样品进行比较的一些变化.
There are several key benefits to collecting samples by the stopped belt method.
1. Safety
The first item, as always, is safety. Stopped belt sampling is a relatively safe method to collect manual samples, as no moving material or operating equipment are involved.
Obviously, 可能会有一些安全问题，从特定的位置产生的样本被移除, but this will vary from facility to facility.
2. Equal probability
Second, the sample is equiprobable, 这意味着所有的材料都经过样品被移除的点，并且可以包括在样品增量中，这取决于输送带何时何地停止.
3. Delimitation
The next item is that the sample increment is properly delimited. 这意味着样品增量的边界是明确定义的——没有外部物质可以进入，也没有内部物质可以逃逸. Only material within the predetermined cutter width will be collected.
这一点很重要，因为皮带上物料的增量质量必须与输送带上的流量成正比，此时增量被收集. Variations in sample increment mass lead to inconsistencies in final save sample, which lead to biased sample analysis.
4. Constant cutter width
下一项是，停止带分带器可以在整个输送带上的物料横截面上保持恒定的宽度. Similar to delimitation, 恒定的刀具宽度对于保持一致和成比例的增量质量至关重要.
5. A full depth sample across the full cross section
In addition to the increment mass concerns, 在横截面的全宽度上收集材料的全深度的增量是很重要的，因为材料不可能在整个横截面上保持一致. 带式输送机尤其如此，因为物料往往在带式输送机上分离.
If material is not collected at full depth, 在输送带横截面底部的材料(细粒)将不能在最终样品中正确表示. If material is not evenly loaded across the conveyor belt, 从皮带的一边或另一边的材料将不正确地表示在最终的样品.
With stopped belt sampling, it is relatively easy to collect all the particles contained within the dividers. It is also relatively easy to verify that all the particles have been collected. Since the belt is stopped, enough time is available to successfully collect the sample.
Stockpile sampling
Perhaps the most common manual sampling method for aggregates is stockpile sampling. There are different approaches to collecting a sample in this fashion, but all methods exhibit the same issues to some degree or another.
Stockpile sampling methods involve collecting material directly from the product pile.
1. Safety issues
Again, the first issue is safety. Sampling from stockpile requires that personnel be on, or at least in very close proximity to, a stockpile. 由于库存在某种程度上是不稳定和不可预测的——尤其是在材料被移走的时候——人员最好远离.
有些方法通过使用移动设备来完成对储存材料的初步清除，使操作人员保持较安全的距离. While this does keep personnel safer, 以这种方式抽样仍然不能解决所收集的样品的其他一些问题.
2. No equal probability
储存中的所有粒子将不会有相同的机会被选为样本的一部分. 由于进入库存的物料通常在输送带上进行隔离, material is not distributed into the stockpile in a uniform way.
Furthermore, once material enters the stockpile, it does not settle in a uniform way, amplifying the issue of non-uniform material distribution within the stockpile. If material is not uniformly distributed, and all particles within the stockpile do not have the same chance of being collected, it is very likely that the accuracy of any samples collected will be reduced. The sample will not closely represent the material present in the stockpile.
3. Not properly delimited
储存的样品也不太可能得到适当的划界(不可能对整个储存进行划界). 如果只考虑库存的一部分，则很难确定将在其中除去样品的物理边界. Again, considering that only a small portion of the stockpile is sampled, it is likely possible to collect a sample of constant width, but this is not possible for the stockpile as a whole.
4. Not possible to sample across full width of depth
不可能从储存的整个横截面或整个深度收集样本, 也就是说，库存成分的变化不会在分析的样本中体现出来. The sample collected is a subjectively located, 仅能真正代表样本采集区域的部分剖面样本.Therefore, 除非库存中的材料在整个库存中非常均匀地分布，否则它不可能准确地代表整个库存.
Transfer point sampling
Aggregate samples are also commonly collected at a transfer point, 例如从一个传送带卸到另一个传送带的下落物料流. 通常，这是用一个小容器或手持切割/收集设备手动完成的.
1. Safer than stockpile sampling
转移点抽样可能比要求人员在库存上或旁边工作更安全, 但它仍然需要人员暴露在操作设备和下降的物料流中(更不用说在下降的物料流中手动插入设备)。.
As a side note, it is probably worth mentioning that automated equipment can be used to safely collect correct samples from a falling material stream.
2. Equal probability
This method of sample collection is at least equiprobable, 因为所有组成要表示的材料的材料都将流过收集点.
3. Possible delimitation
根据所使用的样本收集实现的类型，可能需要考虑划分问题, 尽管如果实现设计得当，应该可以为样本增量获得正确定义的边界.
4. Cutter must move at a constant speed
The major issues with transfer point sampling, however, 是执行设计的功能吗?执行实际上是如何与掉落的物料流交互的. Since this method involves a moving cutter, 重要的是要确保刀具在物料流中以恒定的速度移动，以确保可计算和一致的样品增量. 如果取样装置每次不以恒定的速度在物料流中移动, more or less material can be collected with each increment. This results in a disproportionate amount of sample being collected with each increment, which can cause issues in the final analysis of sample collected.
5. Difficult to sample a full cross section
它也可以是非常困难的手动收集一个完整的横截面的材料从一个下降的物料流, 因为取样装置的尺寸应该足够大，以便在一个完整的截面增量中包含预期的全部材料. 这种数量的材料可能很难手动处理，同时也试图通过物料流来操纵采样设备.
只要采样器具足够大，可以容纳整个增量，并且足够深，以防止在收集增量时材料从采样装置中反弹回来，那么在材料横截面的整个深度收集样品的要求就不是问题.
Automatic sampling with Cross Belt Samplers
The question becomes then, how to collect a correct, representative and consistent sample with minimal impact on plant operations?
似乎理想的情况是将与停止带样品相关的样品完整性与更有效的样品收集手段相结合, or an automated stopped belt cut, so to speak. This is exactly the sort of situation that lends itself well to the use of a Cross Belt Sampler.
在俄克拉何马州的这个地点，麦克菠菜网最稳定正规平台_最全菠菜网大全十字带采样器自动收集混凝土砂样本，以确保质量.
A Cross Belt Sampler is a safe, cost-effective and easily implemented solution that will collect representative samples. It is installed on existing conveyor structure (around the conveyor belt). 当旋转刀具组件进行360度旋转时，采集样品, 在传送带上穿过移动的物料流，并在旋转刀具组件停止时将收集到的样品沉积到取样器的出料槽中.
1. Safety
This means of sample collection is safe, as no operators are exposed to the moving conveyor or material flow.
2. Equal probability
It is also equiprobable, 因为所有的材料都必须通过传送带上的采样器下面，因此有可能被收集作为样品的一部分.
3. Proper delimitation
The sample cutter properly delimits the increment to be collected, 由于增量完全由下面的传送带和刀具侧板在开始和结束. 适当设计的刀具将具有平行的侧板(整个宽度恒定)，可以承受这种类型的应用固有的滥用, and can collect a full cross section of material at the full depth of the material.
4. Collect fine material with Cut Zone System
同样值得注意的是，十字带取样器经常引起的一个问题是，位于材料截面底部的细料可能无法用这种类型的取样器收集到. 虽然它是真实的，这是最困难的材料为交叉带式采样器收集, it is also true that a Cross Belt Sampler can collect this material. The successful collection of fine material is dependent upon proper design and adjustment, as well as the incorporation of a conveyor belt contouring system, such as the McLanahan Cut Zone System.
McLanahan Cut Zone System for Cross Belt Samplers.
A Cut Zone System conforms the conveyor belt to the radius of the sample cutter, which allows for the close adjustment necessary to collect smaller particle sizes. The Cut Zone, along with proper adjustment, will allow for successful implementation of Cross Belt Samplers.
Cutter motion
In Cross Belt Sampler applications, 重要的是要考虑刀具的运动轮廓以及刀具相对于传送带的运动，因为刀具和传送带都在运动. A sample cutter moves through four phases of motion while an increment is collected.
1. Acceleration
The first phase is acceleration. With acceleration, 关键的考虑因素是要确保刀具组件能够在刀具进入正在采样的移动物料流之前加速到其最大转速.
2. Steady state motion
The second phase is steady state motion. Generally, 加速发生得足够快，在进入移动的物料流之前，刀具组件以全速旋转存在一段时间.
3. Material collection
Third, is the actual collection of material. 在刀具运动的这一阶段，刀具组件在刀具与物料流相互作用的整个时间内保持其全转速是很重要的. This is to ensure a correct, accurate and repeatable sample increment. 在收集增量时，带有较小驱动单元的小尺寸采样器通常会变慢. While this allows for a more inexpensive machine, it also compromises the integrity of the sample collected.
4. Deceleration
The last phase of cutter assembly motion is deceleration. 一旦刀具离开移动的物料流，必须非常迅速地进行减速，以便从刀具中排出样品材料，同时保持刀具停止在一个位置，任何没有立即从刀具中抛出的样品材料都可以继续向下滑动并在停置位置从刀具中流出.
The Cross Belt Sampler collects a product sample without stopping the conveyor belt.
Cutter speed
刀具装配的速度相对于输送带的速度也很重要. The tip speed of the cutter is used for comparison purposes with belt speed, but in general, the cutter speed should always be faster than the belt speed. How much faster usually varies by application, but a minimum value is often expressed as a cutter velocity that is at least 1.5 times the conveyor belt velocity. This minimum value is commonly used in a number of industries, though in actuality, it may be advantageous to exceed this minimum value, and faster than minimum speeds are often encountered.
Remote operation
自动化的样品采集方法也提供了远程和/或自动操作的好处. It also provides quality control personnel with a better means of process monitoring, 因为它允许在材料生产到库存并与其他材料混合之前对其进行检查.
Cost savings
抽样设备通常不被视为生产设备-直接与生产成品相关的设备-因此不被视为将产生利润的设备. While that may be technically true, 不采样或不正确采样的成本会对生产设施的底线产生重大影响. These costs may not be immediately visible or easily quantified, 但它们确实存在于可以通过提高采样人员的安全性来实现的节省中, tighter quality control of the end products, 提高了对销售菠菜网最稳定正规平台_最全菠菜网大全进行准确估价的能力，提高了工厂的效率.
The case for Cross Belt Samplers
With an ever-increasing focus on product quality and plant efficiency, 重要的是实施质量控制程序，提供工厂性能和菠菜网最稳定正规平台_最全菠菜网大全规格的高度可靠数据，同时允许工厂的高可用性和效率. In aggregates sampling applications, 交叉带取样器允许质量控制人员和工厂管理人员满足这一重要的妥协.
