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Test Sieving:  Principles and 

Procedures 

 

A Discussion of the Uses, Capabilities, and 

Limitations of Testing Sieves as Analytical Tools 

 
 
 

 

 

 

 

 

 

 

 

 

 

 

www.wstyler.com  

 

 

Summary of Contents for VariSifter VS1000

Page 1: ...VS1000 VariSifter Operation Set up Manual Advantech Manufacturing Inc a W S Tyler Company 8570 Tyler Blvd Mentor OH 44060 T 800 321 6188 F 440 974 0921 E Mail info wstyler com Web Site www wstyler com ...

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Page 3: ... 61 cm x 25 cm x 31 cm Operating Conditions This device will function properly at any non condensing humidity level within the temperature limits of 0 to 120 F 18 to 49 C However for test repeatability it is recommended the ambient temperature and humidity be controlled The sieves and accessories used with this device should never be subjected to temperatures above 125 F 52 C or below 45 F 43 C Ex...

Page 4: ...iSifter has an internal power converter to accommodate various power environments 120V 50Hz 120V 60Hz 220V 50Hz 220V 60Hz VariSifter Sonic Separator Control Panel Frequency Control Frequency Hz of each test may be customized from 15Hz up to 60Hz by turning the Frequency knob Freq on the left side of the control panel A read out of the setting will display on the touch screen both in the analog exp...

Page 5: ...amplitude has been achieved when the heaviest particles are rolling on the sieve surface and no particles are arcing higher than half the height of the sieve surface Manual O Testing Screen The O screen is a troubleshooting module that will be helpful in the event of malfunctions Advantech W S Tyler telephone or email support can assist with walking through the Manual O Testing Screen buttons if n...

Page 6: ...ependently turned on or off per user preference The respective buttons will be green if the function is on and grey if the function has been turned off NOTE When sifting powders 45µm and finer addition of the horizontal tappers may be beneficial Use of the vertical and or horizontal tappers may not necessarily help with static electric charge issues Removing the Stack Assembly The stack assembly c...

Page 7: ...ormed sieves may be used at one time Any combination of sieves accessories or spacers making up the standard stack height equivalent to three precision electroformed sieves may be used When performing separations 30µm or finer use only one precision sieve at a time Preparation for the Analysis To prepare for the analysis of a sample for the first time it will be necessary to perform a few simple t...

Page 8: ...ucing the Powder Discussion of the proper methods of extracting gross samples and preparing test samples for analysis is far too complex to be dealt with here For more information on sample extraction and preparation please refer to the publication Test Sieving Principles and Procedures toward the back of this manual A good rule of thumb is to use the smallest sample size possible that is still re...

Page 9: ...e left side of the test platform is a safety interlock device that prevents the unit from operating if the stack moves out of position This switch will be properly deployed and the circuit activated if the stack is inserted correctly Once the stack assembly is in position the column lock can be released by sliding a thumb and forefinger into the openings between the lowest sieve or spacer and the ...

Page 10: ...als will be helpful For a routine test run When the timer counts down to 0 open the door and follow the procedures listed for Removing the Stack Assembly Caution should be exercised when dismantling the stack assembly to avoid loss of sample retained on the sieves or in the fines collector The parts can be weighed directly on the weighing device removing the need to transfer the material to a weig...

Page 11: ...Instructions on the jewel case CAUTIONS U S Standard Sieve Series Improper handling can cause serious damage to the sieve openings and accelerate sieve failure DO NOT remove particles clogging sieve openings with a needle or other sharp object DO NOT use compressed air to clean the sieves or dislodge trapped particles Precision Electroformed Sieve Series Store the precision electroformed sieves in...

Page 12: ...h Servicing the VariSifter Sonic Separator Unit Only personnel qualified by Advantech W S Tyler should service the VariSifter If any performance or operational problems arise please contact Advantech W S Tyler directly VARISIFTER LIMITED WARRANTY Advantech W S Tyler guarantees all its apparatus against defective material and workmanship for a period of one year from the date of delivery This guara...

Page 13: ...Test Sieving Principles and Procedures A Discussion of the Uses Capabilities and Limitations of Testing Sieves as Analytical Tools www wstyler com ...

Page 14: ... Our aim is to provide assistance to both the experienced and non experienced particle technologist in developing comprehensive particle size test results reduce test variations and enable the user to isolate and identify sources of error or variations in the data If additional help is desired in establishing your sieve analysis procedure or if you desire a list of suppliers of the equipment highl...

Page 15: ...SIEVING CHAPTER 2 USES LIMITATIONS AND ADVANTAGES CHAPTER 3 WORKING GLOSSARY OF SIEVING TERMS CHAPTER 4 SIEVE SPECIFICATIONS CHAPTER 5 SIEVE CALIBRATION PROCEDURES CHAPTER 6 PERFORMING THE SIEVE ANALYSIS CHAPTER 7 SIEVE CARE AND CLEANING ...

Page 16: ...acy and durability At present this woven cloth is available in a range of sizes from 125 mm 5 openings to 20 micrometer openings All mesh sizes are covered by both national and international standards The need for particle size analysis in the finer size ranges i e 38 micrometers and less prompted the development of the electrodeposited sieve These sieves sometimes called electroformed or micromes...

Page 17: ...chunks of over 114 3 mm 4 in diameter to slurred alumina and porcelain powders of less than 20 micrometers are all analyzed with test sieves on a regular basis Whether hand or machine sieving wet or dry preparations analysis or production work testing sieves have found a niche in the quality control laboratory Given this overall acceptance of test sieves as a viable analytical device and the wides...

Page 18: ...e most accurate test sieve available would be of minimal use if the relative humidity in the test lab was 99 Extremely dry conditions can cause fine powders to adhere to the sieve components and each other with strong electrostatic charges Additional types of sieving problems are discussed in the glossary section To minimize error caused by wire cloth variation steps must be taken at every stage o...

Page 19: ...articles which build up on the wire mesh and eventually close off the openings Frequently referred to as pegging Photo Page 4 Cover stamped or spun lid that tightly covers the top of a sieve to prevent the loss of the material sample during sifting or mechanical agitation Electrostatic charges accumulation of electrical charges on the particles and sieve components causing clinging agglomeration o...

Page 20: ...n a rigid frame usually for laboratory testing or small scale production applications The frames can be made of various materials the most common of which are brass and stainless steel in a cylindrical configuration having a diameter of 3 5 6 8 10 12 or larger Wet sieving the separation of fines from the coarse portion of a sample while suspended in an aqueous solution introduced to a testing siev...

Page 21: ...e technology today Once again the ubiquitous nature of stacks of test sieves in powder labs around the world has contributed to the scope of the dilemma in sieve standardization and calibration Kaye states The inaccuracies and the uncertainties of characterization by sieve fractionation arise from the experimental problems of determining the sieve residues and from the non ideal nature of the siev...

Page 22: ...omparably they do not meet the basic criteria of ASTM specifications which should disqualify them from use as a U S Standard Testing sieve Another problem encountered with material matching is the use of reference samples that are different in shape size or density than the users products For example a manufacturer of spherical steel shot would yield significantly different results on a sieve that...

Page 23: ... shipment to the customer The way the samples are extracted from the original bulk volume varies with the way the materials are received produced or stored The ideal sampling method is one which provides the most representative sample with the least amount of material required The following paragraphs were first published in the ASTM technical publication STP 447 A The collaborative efforts of the...

Page 24: ...at the base the percentage of coarse particles will be greater Therefore neither location will be representative of the whole In a shoveling process every fifth or tenth shovel etc should be taken depending on the amount of the sample desired The sample should consist of small quantities taken at random from as many parts of the pile as are accessible and taken in a manner that the composite will ...

Page 25: ...resentative of the whole thus destroying the representative quality of the sample Size of Sample in the Test There is a natural tendency although incorrect to use an excessively large sample in the test In most cases a smaller sample will provide a more accurate analysis Beware however that the more you split the greater the chance of error Testing sieves are a go or no go gauge if the sample is t...

Page 26: ...should be assembled with the coarsest sieve at the top of the stack and the balance of the stack in increasing magnitude of fineness increasing sieve numbers with smaller openings The stack should include a cover on the top sieve and a pan below the finest sieve The sieve stack can be shaken then rapped by hand or mounted in a sieve shaker with a motorized or electrostatic drive mechanism While ma...

Page 27: ...ged in the sieve s openings the sieve is inverted over a sheet of paper or suitable collector and the underside of the wire cloth brushed gently with a nylon paint brush with bristles cut to a 25 4 mm 1 length The side of the sieve frame may be tapped gently with the handle of the brush to dislodge the particles between brush strokes At no time should a needle or other sharp object be used to remo...

Page 28: ...he end of a shift or at the end of a week but must be done regularly to assure accurate sieving results The sieves should be immersed in an ultrasonic cleaner filled with a solution of a mild detergent and water Prior to reuse ensure that the test sieves are dried thoroughly Ultrasonic cleaning prevents the buildup of particles trapped in the sieve openings and prolongs the useful life of the siev...

Page 29: ...heat of the soldering iron can distort the openings Epoxies have been used for repairs but tend to block a large percentage of the openings reducing the opportunity for particles to pass through the openings in the allotted agitation time Epoxies may become too brittle for the flexing of the wire cloth and can fracture with use Good general laboratory procedures should be observed with testing sie...

Page 30: ... critical with a testing sieve as they are with other more sophisticated particle size analyzers Compliance with applicable industry national and international specifications is essential The intent of these regulating bodies is the formulation of general standards to assure uniformity in testing standards observed by both the buyer and producer The accepted specification should be the foundation ...

Page 31: ...sevier Sequoiz S A Lausanne 24 1979 3 Heywood Harold Proc Particle Size Analysis Conference Bradford 1970 4 Leschonski Kurt Ibid 5 Kaye Brian Direct Characterization of Fine Particles John Wiley and Sons New York 1981 6 Gaudin A M Principles of Meneral Dressing McGraw Hill New York 1939 7 Manual on Test Sieving Methods STP 447 A American Society of Testing and Materials Philadelphia 1969 ...

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Page 33: ... 58 0 71 0 6 0 82 1 18 No 16 0 0469 0 040 0 16 1 34 0 63 0 54 0 72 1 No 18 0 0394 0 034 0 14 1 14 0 56 0 48 0 64 micrometer inches micrometer micrometer micrometer millimeter 850 No 20 0 0331 29 1 127 977 0 5 0 43 0 58 710 No 25 0 0278 24 7 112 822 0 45 0 38 0 52 600 No 30 0 0234 21 2 101 701 0 4 0 34 0 46 500 No 35 0 0197 18 0 89 589 0 315 0 27 0 36 425 No 40 0 0165 15 5 81 506 0 28 0 24 0 32 355...

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Page 40: ...th this rule 4 How long should I run my test Generally there are industry or in house standards for sieving durations For instructions on determining the optimum test time please refer to the Recommended Time Intervals section in Chapter 6 Performing the Sieve Analysis in the Test Sieving Principles and Procedures manual Generally the VariSifter test is complete when media is no longer filtering i...

Page 41: ...ylic frames so sample media can be viewed while the test is running The appropriate amplitude has been achieved when the largest particles of the sample are observed rolling on the sieve surface and none arc higher than half the height of the sieve frame Particles that are arcing too high will be forced back into the sieve above thereby altering the test results 9 Does the VariSifter have to be ca...

Page 42: ...answered For further technical support please contact our Tech Support Team at Advantech Manufacturing Inc a W S Tyler Company 8570 Tyler Blvd Mentor OH 44060 T 800 321 6188 F 440 974 0921 E Mail info wstyler com Web Site www wstyler com ...

Page 43: ...he fines collector collects the minus material that has passed through the stack assembly Fines Collector Holder L3 N6 The fines collector holder is used to hold the fines collector and is the base of the stack assembly Stack Assembly L3 N7 Consists of column lock diaphragm fines collector fines collector holder top cone and selected sieves or spacers This device is where the sample is placed for ...

Page 44: ...correctly If the stack assembly is not the problem the cam assembly may be out of alignment or the trigger spring may be broken Unit works but shuts off before timer hits zero Stack assembly has not been unlatched Unit runs but lacks power The Column Lock tends to spring open unexpectedly Possible defective driver The arms on the Column Lock may have fallen out of adjustment Gently bend the arms t...

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