download THE BEGINNER¢â‚¬â„¢S GUIDE TO INDUSTRIAL REPRESENTATIVE Basic grab sampling such as a bucket and spigot

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    Why representative sampling is important to operational success

  • © 2016 Sentry Equipment Corp.

    Running an efficient operation requires controlled, real-time data obtained through representative sampling.

    What is representative sampling? Representative sampling is the act of capturing a limited volume of material from a process stream that accurately reflects the characteristics of the entire lot, batch or process stream. Most material within a production environment or when being stored and transported can be sampled and then analyzed for product quality and process monitoring.

    Basic grab sampling such as a bucket and spigot collection or a bin scooping method merely reflect insights into the process stream at the point in time when the sample was collected. Depending on the characteristics of the materials being sampled and the process conditions, a grab sample may not be suitable due to segregation or separation. It also can be very dangerous. There are also many human errors that can come into play when using a grab sample approach, creating uncertainty in the sample analysis results.

    On the other hand, composite sampling consists of a collection of numerous individual samples taken at regular intervals over a period of time using the appropriate sampling technique for the application. The material being sampled is collected into a sample container for analysis off line in a laboratory, or the sample is conditioned and sent directly to an on-line analyzer. Additionally, the number and specific locations of your samplers has an impact on whether they truly will be representative of your complete process.


    The controlled methods of representative industrial sampling: • Provide reliable and accurate analysis results • Save money by reducing waste and downtime • Protect operators and the environment • Ensure product quality and regulatory compliance

    Let’s take a closer look at how representative sampling helps chemists, maintenance planners, engineers, plant managers, QA managers and operators collect reliable samples. Representative sampling combines safety, simplicity and accuracy to deliver benefits unmatched by other sampling methods.


    Garbage in, garbage out. This expression originating from the computer science industry refers to an electronic device (a computer) that will unquestioningly process unintended input (garbage in) to produce nonsensical or undesired results (garbage out). This sentiment certainly applies to sampling and analysis, conducted either in situ or off line in a lab.

    To avoid garbage inputs and increase confidence in your product quality or process, obtaining representative samples for accurate analysis is dependent upon the application and the quality of the sampling methods themselves. Or in other words, your sampling


  • © 2016 Sentry Equipment Corp.

    Should these application criteria be overlooked, the samples taken will not sufficiently represent the complete lot, batch or process stream. Most importantly, many samples may need to be conditioned by bringing the temperature, pressure and flow rate to a suitable state for reliable analysis. Should this conditioning step be ignored or not conducted properly, the sample analysis results could lead to misguided operational decisions that directly impact customer loyalty, profitability or safety.


    Process monitoring Representative sampling and analysis is essential for efficiently monitoring plant processes and maximizing output. Many operating environments run very harsh materials through their equipment. Plant assets are a significant investment and vital to the success of maximizing output and profitability. Therefore, monitoring is an important part of process control for many industries, especially power generation, oil & gas, petrochemical, chemical and others.

    To regularly monitor the chemical properties of the process stream and their impact on pipelines, storage tanks, turbines or other equipment, representative sampling must be collected, conditioned as needed and regularly analyzed to avoid downtime. Neglecting monitoring puts your plant assests and equipment at risk of catastrophic failures, environmental spills or, even worse, fatal accidents.


    Conveying Area Classification Gas Abrasive Distillation Towers Composition Liquid Boiling Point Mixers Corrosiveness Powder Density Pipes Flammability Slurry Explosive Reactors Flow Rate Solid Freezing Point Storage Vessels Pressure Steam Hardness

    Radioactivity Water Magnetic Temperature Moisture Content Toxicity Particle Size

    Particle Shape Material Compatibility Thermal Conductivity Stratification Vapor Pressure Viscosity

    method should be designed for the specific process stream, process conditions, materials characteristics, safety hazards, certification standards and regulatory requirements.



  • © 2016 Sentry Equipment Corp.

    Yield improvement In the food and beverage industry, as an example, a plant must maintain proper moisture content to stay profitable. To avoid potential product waste, the moisture content of ingredients or finished food products must be monitored by representative sampling and analysis in order to:

    • Detect moisture irregularities • Identify over-drying or under-drying • Screen for product breakage

    One specific way a plant can improve its yield is by keeping ingredient moisture content in the proper band. If it is too low, a plant may be giving away product, and if it is too high, the product will deteriorate more quickly. Improper moisture content also is key in product shrinkage or expansion, which directly affects the volume a product takes up in packaging. Plus, by sampling after a dryer, a plant can not only identify if a product is being over-dried or under-dried, but also monitor and control the drier power consumption.

    In addition, sampling can help monitor product breakage to identify potential disruptions or issues within the process. Poor performance of the sizing equipment can result in a direct increase in product needing to be discarded in landfills or sold at lower price points for non-target users.

    Process optimization In the power generation industry, for example, automated sample conditioning and analysis systems easily and safely condition and analyze with limited human interface. In a chemical or food processing plant, for example, an automatic sampler can ensure sample integrity and provide several other advantages:

    • Production continues during sampling with no downtime • The sampler controller can be incorporated into existing equipment to allow sampling to begin

    without operator engagement • Operators are not exposed to potentially harmful equipment pressure and temperatures • Consumer protection is enhanced because operators cannot inadvertently contaminate the process • Plants can cycle up much faster, saving time and money


    In many manufacturing plants or facilities, process streams are maintained at certain temperatures, pressure and flow rates. The vessel from which the sample is retrieved – pipes, tanks, mixers, conveying belts, chutes, towers, reactors or other equipment – must be taken into consideration in developing the best sampling method. Automatic or manual samplers or fully integrated sample conditioning and analysis systems should be installed in the right location(s), capturing the right sample volumes at the right frequency using a sampling technique compatible with the application criteria.

    Each operation is different, yet your product quality and processes must be consistent, based on trusted data. That’s why your sampling methods must be compatible with the characteristics of the process


  • © 2016 Sentry Equipment Corp.

    material to ensure safety without sacrificing representation. For example, sampling a gas that is extremely flammable held under high pressure in a pipeline would require a very different method than a small particle-sized solid material free flowing from a conveyor belt. Or a viscous slurry with moisture content would require a different sampling solution than a radioactive wastewater application.

    Many operational environments must handle hazardous products or wastes such as deadly H2S (hydrogen sulfide) sour gas or water, explosive materials or toxic or abrasive materials. A grab sample approach in this type of environment would pose a health and safety risk to operators and the environment.

    Operator safety Many manufacturers are closely aligned to regulations that ensure the safety of their employees. For example, The Occupational Safety and Health Administration (OSHA) enforces U.S. federal government mandates regarding workplace safety, while the International Labour Organization (ILO) works with over 180 member countries to ensure occupational safety and health for workers. Employers are required to strictly follow employee safety regulations or risk sanctions and other penalties.

    To that end, closed-looped, representative sampling is an ideal solution. The design of these samplers protects operators by:

    • Keeping liquids and gases fully contained to eliminate worker exposure to hazardous vapors and potentially scalding fluids