Presentation is loading. Please wait.

Presentation is loading. Please wait.

Sentry Equipment Corporation

Similar presentations

Presentation on theme: "Sentry Equipment Corporation"— Presentation transcript:

1 Sentry Equipment Corporation
Process Sampling Sentry Equipment Corporation

2 Objective Gain an understanding of the methods to obtain representative samples Review the fundamentals of gases, liquids and bulk solids Overview of analyzing methods Review the integration of sampling with on-line instrumentation

3 Why do we sample? Product mix characteristics
Examples: Particle size, bacteria count, chemistry, etc. Identify process variations Process control Environmental monitoring Product quality assurance Custody transfer

4 What kind of sample? “True” overall average of the entire lot for one or many characteristics Representative sample Characteristics of the sample equal that of the entire lot or batch Consistent, accurate, and repeatable

5 How to get a representative sample
Follow protocol that gets a consistent, accurate, and repeatable sample Understand the material physical properties Use techniques that have as little sample bias as possible Profile the process and sampling system (i.e.. Liquids, slurries, gases, bulk solids, etc.) Reduce sample to sample variation Sample methods and results must be repeatable

6 Sampling Errors Process analysis is only as good as the quality and representivity of the sample itself Sampling errors are costly because they can lead to: Unnecessary process changes Additional analysis of more samples Release of off-spec product to the customers Scrap of good material The Sampling Scapegoat

7 General Sampling Practices
Understand the process and the sampling objective to help select the proper device I.e. Gas concentration, liquid chemistry, bulk solids particle size analysis Determine the best sampler location Take several increments and composite them to form the “sample” Composite Sample – A sample obtained by combining several distinct sub-samples or increments Sample frequently enough to identify process cycles

8 Direct Sampling Typically includes dipping a cup or container into an open vessel or opening a spigot on a vessel that may be under pressure May require the process to be interrupted in order to sample This sampling technique is generally considered unsafe Operator is exposed to any process or environmental hazards Direct sampling introduces the ability for sample variations due to human error and sample contamination

9 Indirect Sampling Indirect sampling isolates the operator from the process hazards Maintains a closed system Sample integrity preserved Allows the process to be sampled during normal production cycle

10 A few general sampling practices
Mix the material prior to sampling (if possible) Take several increments and composite them to form the “sample” Composite Sample – A sample obtained by combining several distinct sub samples or increments Collect the sample in a container that will not react with the sample Sample frequently enough to identify process cycles

11 A few general sampling practices (cont.)
Determine the correct size required for the sample Use a sampler and sampling process that removes bias Understand the process Sampling practices may vary from process to process

12 Three categories for sampling variation
Process variations/cycles Material variation Tool and techniques Including sample handling

13 Process Variations Be aware that the process and its conditions may vary over time Examine the sampling results and the effects of sampling frequency Use the sampler and sampling system to verify the process

14 Ways to reduce material variation
Determine the appropriate mass of the actual sample Provides a better idea about the overall properties of the lot Collect several increments from the lot and form a composite sample Condition the material prior to sampling Mix the sample if possible Control the temperature, pressure, flow, etc. Control the particle size

15 Product Characteristics
Identification of the product characteristics is critical for obtaining a representative sample Every gas, liquid, and bulk solid has its own unique physical property Many processes contain entrained gases that can expand when decompressed Venting provisions must be taken into account Bulk solid characteristics can be very unpredictable Some may pack one moment and fluidize the next Two grades of the same material may act differently

16 Flow Characteristics Mass Flow Funnel Flow Arching/Bridging Rat-holing
Flooding Segregation Improper bin design affects the flow of solids in the bin or hopper.

17 Material Properties Abrasive – Materials that wear, grind, or rub on the inside of the sampler or any moving part Arching/Bridging – Materials that tend to form a bridge-like structure Free-Flowing – Materials that generally flow under the influence of gravity without the aid of agitation Floodable – Materials that aerate to a point where they begin to flow like a liquid Hygroscopic – Materials that tend to absorb and retain moisture from the atmosphere

18 Material Properties Cohesive – Materials that tend to stick to itself
Adhesive – Materials that tend to adhere or stick to components of the sampler Friable – Materials that are easily pulverized or broken apart Static Generating – Materials that generate static from friction on itself or within the sampler

19 Bulk Density Mass per unit of volume in powder form, including the air trapped between the particles Measured in g/cc, kg/l, lb/ft3 Examples: Cake Mix = 44 lb/ft3 (0.705 g/cc) Cement Powder = 85 lb/ft3 (1.361 g/cc) Oats = 27 lb/ft3 (0.432 g/cc) Parsley Flakes = 3 lb/ft3 (0.048 g/cc) Sand = 99 lb/ft3 (1.586 g/cc) Tungsten Carbide = 250 lb/ft3 (4.004 g/cc)

20 Tools and Techniques

21 Sampling Tool The sampling tool is critical for providing a representative sample The sampler must assure the sample integrity is preserved Understand the analysis requirements to help determine which sampler to choose Understand the process variables that may impact the sampler design The sampler should keep the operator safe from any process or environmental hazards

22 Principle for correct sampling
Every part of the lot has an equal chance of being in the sample Integrity of the sample is preserved before, during, and after sampling Oxidation, abrasion, evaporation, and contamination are examples of improper handling Vapor pressure is an important characteristic to take into account when sampling The measure of the tendency of a material to form a vapor.

23 Manual “Grab” Samples Typically, manual grab sampling is a poor, but common practice because it is taken from the most accessible part of the batch/process Exception is when the sampler is located in a proper/acceptable sample point and other good practices are recognized

24 Gas Sampling Maintain pressure and sample integrity
Monitor H2S, VOCs, water content Speed loops and analyzers are common

25 Liquid Sampling Control pressure, temperature, flow rate
Monitor pH, DO, Sodium, conductivity, TOCs, chemistry, etc. On-line analysis is common

26 Bulk Solids Sampling Material characteristics and flow properties vary
Monitor moisture, particle size, shape, etc Difficult to analyze on-line Material waste

27 Bulk Solids Sampling Point Sample Strip Sample Cross Cut Sample

28 Point Samplers Takes a sample from a point in the material stream
Used when conducting chemical analysis or when material is homogenous

29 Strip Samplers Takes a sample from a narrow portion of the stream
Used in situations where product segregation exists

30 Cross Cut Samplers Takes a cross-section of the entire product stream
Provides the most representative sample, but requires a lot of headroom

31 Types of Measurements and Technology

32 Frequent Sample analysis conducted in real time
Off, At and On-Line Off-Line At-Line Sample removed and tested locally On-Line Frequent Sample analysis conducted in real time Lab Testing Infrequent Samples sent to a remote location 

33 Measurements/Analysis
Effusivity NIR IR Laser Induced Fluorescence Light Scattering Imaging Particle Size Moisture Chemical Composition Surface Area Shape Temperature Dissolved Oxygen

34 Knowledge What you know don’t know What you don’t know that you don’t know Monitoring multiple properties provides insights into areas and mechanisms that have not been investigated

35 Summary Sampling is a critical part of process control and is often overlooked Indirect methods of sampling are the safest, yet most challenging The goal is to get representative samples Material and process variations as well as sampling techniques and tools effect our ability to get representative samples Understand the process and sampling objectives 2 - New Rep Low E.ppt

Download ppt "Sentry Equipment Corporation"

Similar presentations

Ads by Google