sources of error in hydrometer analysis

Random sampling creates subsamples with varying particle distributions, which can be observed in the poor reproducibility of the measurement results (Fig. Sources and Types of Error Every experimental measurement, no matter how carefully you take it, contains some amount of uncertainty or error. This is called representative sampling. In the first example (Fig. Image Credit:Microtrac MRB, Figure 3a. Recommended for you Document continues below. Cited by (0) Consequently, the quantity must be reduced further in the laboratory. It is said that in hydrometer analysis, much error arises from many causes, and it brings about the error for the values of percent finer by mass and particle size calculated using Stokes' law. GTM-13, Revision 2. When sampling inhomogeneous bulk materials, it is important to ensure that the properties of the sample taken in the laboratory correspond to those of the total quantity. The basis for this test is Stokes Law for falling spheres in a viscous fluid in which the terminal velocity of fall depends on the grain diameter and the densities of the grains in suspension and of the fluid. Measurements at 20 to 50 kPa yield identical results, from 100 kPa the result becomes finer, indicating progressive destruction of the particles. What are the possible sources of error for grain size analysis tests including mechanical and hydrometer analysis tests? Figure 2: Grain Size Distribution curve of a medium-fine sand. The purpose of the analysis is to derive the particle size distribution of soils. Therefore, Cu is estimated as: When Cu is greater than 4, the soil is classified as well graded, whereas when Cu is less than 4 the soil is classified as poorly graded/uniformly graded. Possible testing errors include: temperature fluctuation during the experiment, sample loss during agitation, disturbance of suspension when the hydrometer was inserted, accumulation of soil on the hydrometer bulb, evaporation, and misreading of the meniscus. and gently insert the hydrometer into the suspension. Produced from materials originally authored by Dipl.-Phys. Such Standard Operating Procedures (SOPs) continually ensure the same, defined measurement processes and work steps. methods such as seive shaking are:- See Answer See Answer See Answer done loading Microtrac MRB's product range for particle size and shape analysis includes techniques such as Dynamic Image Analysis, Laser Diffraction and Dynamic Light Scattering. The nomenclature of the sieves typically used for Grain Size Analysis of soils as well as the corresponding opening sizes are presented in Table 1. (NOTE: 100 mL + 880 mL = 980 mL the missing 20 mL accounts for the approximate volume occupied by 50 grams of soil). Figure 6. The second reading gives a measure of the percent of clay in suspension. Please use one of the following formats to cite this article in your essay, paper or report: Microtrac MRB. This problem has been solved! The distribution density is the first derivative of the cumulative curve. Sieve Grain Size Analysis is capable of determining the particles size ranging from 0.075 mm to 100 mm. There are 2 correct answers - select both. Since the required amount of particle detections is dependent on the size of the particles, and even more so on the distribution width, it is hard to give a general recommendation. Q 1&2: source of Errors in LAb experiment: Hrdrometer Analysis Due to incorrect reading of meniscus due to Temp variation from standard temp. For sieve analysis, both objects are equal in size, they have an equivalent diameter of 14-16 mm, it is not possible to achieve greater precision with sieve analysis. Want to create or adapt books like this? 200 sieve on the bottom of the stack. Automatic rotating sample dividers, such as the Retsch PT 100, deliver the best dividing results (Fig. sources of error in hydrometer analysis Kai Dffels from Microtrac Retsch GmbH. 10 0 obj << /Length 11 0 R /Filter /FlateDecode >> stream Analysis of the test results Complete the table provided and show one sample calculation. Prepare a deflocculating agent. Four measurements with the CAMSIZER P4 image analyzer (red / blue / violet / green) provide four different results. Obtain the effective hydrometer depth (L in cm) for the corrected meniscus reading from Table 4-1. Taking the easy way out and always using 100 grams tends to lead to a dead-end, because 100 grams can sometimes be too much or too little. You'll get better resolution on the errors at the top of the range, and any measurement errors, or reading errors will make up a smaller portion of the results. Soil deposits consist of the soil particles and the void space between the particles. 'Hydrometer Analysis Introduction -Hydrometer analysis is the procedure generally adopted for determination of the particle-size distribution in a soil for the fraction that is finer than No. "1A#279BQXaqx$8Rw(3SYgv%&4CEu)6:HIWbcrt = !1AQaq"2BRbr#CS3s ? The Stokes law calculates the larger possibly diameter of the particles that are in suspension. 20 kPa (red), 30 kPa (brown), 50 kPa (orange), 100 kPa (violet), 100 kPa (purple), 150 kPa (gray), 200 kPa (green), 300 kPa (dark green) and 460 kPa (blue). While considerably more sophisticated techniques have appeared. Size distributions can be separately recorded for length and width. Present the study report with clear Introduction and Conclusion including your own, Select a Saudi company that operates in Europe and/or Africa, and write report covering the following points: 1. What to do: Answer the given question. No change can be detected from 150 kPa to 250 kPa. In test method for particle size distribution of soils, sieve analysis result and hydrometer analysis result may not be skillfully connected. Learn more about how Pressbooks supports open publishing practices. 3b), the dispersion becomes increasingly fine from a pressure of 100 kPa, which indicates that the particles are ground. Shake the control cylinder to mix the contents thoroughly. 7.9 Record the hydrometer reading at 40 sec. The hydrometer test from the previous lab was conducted with different soil than the soil used in this lab, this means if the Activity (A) were determined, it would not be useful in any way because the soils are different. the apparatus that was used during this lab. in masse. %PDF-1.2 Make sure you read the method for using a volumetric flask correctly. 1b). Add 5gr of sodium hexametaphosphate solution and utilize a high-speed mixer to disperse it (~3 min.). In the example in Fig. Therefore, for this sample, 150 kPa would be the optimum dispersion pressure. **. Physical errors may also occur, since a sample is never completely homogeneous. Generally, when selecting the dispersion pressure the rule applies as much as necessary and as little as possible. /Subtype/Image Therefore, it is hardly representative to only take a sample froma single location. is the weight of the soil sample in grams. Let the mixture sit over night (a minimum of 12 hours) to allow the solution to effectively disperse the soil separates (sand, silt, clay). Other methods, such as hand measurement with a caliper, offer number-based distributions predicated on an amount of particles in each measurement class. The hydrometer analysis is utilized for particle sizes finer than 75 m. The hydrometer analysis is a widely used method of obtaining an estimate of the distribution of soil particle sizes from the #200 (0.075 mm) sieve to around 0.001 mm. (Note: It should take about ten seconds to insert or remove the hydrometer to minimize any disturbance, and the release of the hydrometer should be made as close to the reading depth as possible to avoid excessive bobbing.). Slowly insert the hydrometer device into the container and take readings at 10, 20, 40, 60 and 120 seconds, respectively. Calculation of the size distribution is therefore indirect. (Repeat 7.8 - 7.9 for each sample) 7.10 Record the hydrometer reading again after 6 hours, 52 minutes. Sample division with rotating sample divider provides four identical and correct results. /Filter/DCTDecode The histogram representation is intuitively easy to access, where the bar width serves as the lower and upper limit of the measurement class and the height is relative to the number of particles in the respective size interval. Once percent sand, silt, and clay are known for a sample, the soil can be classified by textural class using the textural triangle. /Name/Im1 Hydrometer analysis is essential for obtaining the complete particle size distribution of such soils. For more information on this source, please visit Microtrac MRB. It is recommended to break up these agglomerates prior to taking measurements. Conversely, if too little sample is analyzed, the result will be inconsistent and poorly repeatable due tothe small number of detections. 10. It is recommended that work instructions are published that are as precise and easy-to-follow as possible to ensure measurement results of consistent quality. jkD! If the number of oversize particles is small, the contribution of these particles is insufficient (signal/noise ratio) to appear in the result. dissolved particles moving around randomly in the fluid column. During laser diffraction, all diffraction signals are assessed as if they were produced by ideally spherical model particles. 4 sieve should be on top and the No. For example, if youre measuring length with an elastic string, youll need to decide with your peers when the string is tight enough without stretching it. With finer particles, the error is more likely to happen during the dispersion phase. Based on Stokes Law, it is known that sand size particles (0.05 mm to 2 mm) fall from suspension rapidly. The method is based on Stoke's law governing the rate of sedimentation of particles suspended in water. Indeed, the use of Hydrometer Analysis is necessary in this case. Hence, it is necessary to divide the quantity in the measurement class by the class width. Course Hero is not sponsored or endorsed by any college or university. You'll get a detailed solution from a subject matter expert that helps you learn core concepts. The formula of Stokes Law is presented below: D: The maximum diameter of soil particles corresponding to the percentages indicated by a single hydrometer test reading. When we want to implement any engineering problem in computer at that time already inherent errors may exist in the problem. In this instance, the measurement data are mainly distributed based on a number. Properties and Behavior of Soil - Online Lab Manual by MD Sahadat Hossain, Ph.D., P.E. The analysis is conducted via two techniques. This occurs because the scattering intensity expands with size by a factor of 106, which indicates that a 100 nm particle scatters a million times more photons than a 10 nm particle. However, these percentages can wildly vary in meaning. By continuing to browse this site you agree to our use of cookies. The particle size distribution of soil containing a significant number of finer particles (silt and clay) cannot be performed by sieve analysis. Generally speaking, the larger the particles, the greater the probability of error in sampling and sample splitting. If temperature is above 68 F, add 0.2 units to the blank hydrometer reading for EACH degree above 68 . Insert the hydrometer and thermometer into the control cylinder and note the zero correction and temperature, respectively. /ColorSpace/DeviceRGB Since the number decreases with increasing particle size, the number-related proportions (P0) are higher in those of the small grinding balls. Here, measurement method sensitivity plays a decisive role. Place 500-600 ml of distilled water in a steel mixing cup. MD Sahadat Hossain, Ph.D., P.E. In contrast to image analysis, in laser diffraction the particle shape cannot be identified. analysis is limited to those materials which have diameter larger than No.200 Sieve (0.075mm). E5Ge0l&8#d n)]s*>JrI Rx@ {O0 `;wv/['"1Y}1KpF^:ppx@(}0, This should be allowed to soak for about 8 to 12 hours. 200. 200) of the Sieve Analysis. Dispersing Agent: Sodium Hexametaphosphate, Table 4.1: Values of effective depth based on hydrometer and sedimentation cylinder of specific sizes, Table 4.2: Values of k for computing diameter of particle in hydrometer analysis, Table 4.3: Temperature correction factors, C, Table 4.4: Correction factors a for unit weight of solids. These size intervals are generally established by utilizing the performance and resolution of the measurement system used. Summary of Methods The percentage retained on each sieve is determined by dividing each weight retained by the initial weight of the soil sample. This is also why its good to take data starting with different specimens each time (if applicable), rather than always following the same sequence. THE ACCURACY OF HYDROMETER ANALYSIS FOR FINE-GRAINED CLAY PARTICLES TRID the TRIS and ITRD database THE ACCURACY OF HYDROMETER ANALYSIS FOR FINE-GRAINED CLAY PARTICLES The Standard Test Method for Particle-Size Analysis (ASTM D422-63) relies on the well-known Stokes' equation for estimating particle diameters. Converting laser diffraction results to number distributions is also possible, but since only a simple spherical model is available, this is less precise, and it is recommended that the volume distribution should be used when possible. This includes human error in measurement, calculations, and time management, although timing was not the biggest factor. Cive 334 - Dr Song - Experiment': Consolidation Test Report - 2018 April. Record this as the. Therefore, the soil particles are distributed as they are retained by the different sieves. A PowerPoint presentation is created to understand the background and method of this experiment. Obtain the value of K from Table 4-2 if the G. Calculate the equivalent particle diameter by using the following formula: Determine correction factor a from Table 4-4 using G. Calculate the corrected hydrometer reading as follows: Plot the grain size curve D versus the adjusted percent finer on the semilogarithmic sheet. The methods used have usually been established for years and are rarely questioned. 3. Microtrac MRB. This includes human error in measurement, calculations, and time. In imaging techniques (e.g., as used by CAMSIZER), various size definitions can be achieved.

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