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3. Hazards and Controls Evaluation3.1 Possible fire eventThe apparatus is not associated with high temperatures but in the event offire due to some other high temperature associated equipment in operation,you are to evacuate the room immediately. Pull the nearest fire alarm (see C23 floor plan). Should you return to attempt to extinguish the fire, do not doso alone. Make only one attempt and if unsuccessful leave the labimmediately. If successful, stay at the scene and have someone alert theSecurity and Traffic department (ph. # 4830) and the Environmental Healthand Safety office (ph. # 5075). Please refer to C-23, Head hall floor plan tosee the locations of fire extinguishers, fire alarm pull station and first aid kit.3.2 VentilationThere are no ventilation fans in room C-23 other than the fume hoods. Thelab is centrally ventilated as fresh air is introduced at all times into the room.Proper ventilation system is not a requirement for the operation of apparatus.3.3 Kinetic, Thermal and AcousticThe hardness testers are not associated with thermal and acoustic hazards.The moving parts of the hardness testers are operating handle, elevatingscrew, capstan and major load/static weights. They do not pose a seriousthreat if they are handled carefully by the operator. The operator should wearsafety goggles while using the apparatus to prevent stray metal chips fromdamaging his eyes.3.4 ElectricalThere are no electrical hazards associated with the hardness testers as thereis no component of any of these four models that is electrically powered.3.5 General, physical and equipment concernsThe knurled screw on the dashpot control of CLARK Hardness TesterModel (CR - 8 & C 12 A) speeds up or retards the application of major load.The knurled screw should be turned counterclockwise to increase the speedand clockwise to decrease the speed. The knurled screw should never beturned completely out, as this will inevitably result in impact loadingand chipped metals or diamonds. This creates conditions that are unsafefor the operator.17

The CLARK Hardness Tester Model (CR - 8 & C 12 A) should never beoperated without an adequate supply of oil in the dashpot. Similarly thePITTSBURGH (Brinell Hardness Tester) should never be operated withoutan adequate supply of oil in the oil reservoir.On the WILSON 103 R hardness tester, the major load/static weightadjusting dial should be always turned clockwise. Do not turn the staticweight adjusting dial anticlockwise. Only operate major load adjustingdial with the operating handle/lever in the forward direction.The CLARK CR - 8 Model is also provided with a dust cover to prevent theapparatus body from dust and grit. After using the CLARK CR - 8 hardnesstester, cover it with Dust Cover (see Figure 12).The test specimens provided with the apparatus, when tested should beindented on one side only. If the test specimen has indentations andimpressions on both of its sides then it will give inaccurate results to theoperator and is of no value to the experiment. The test specimen shouldalways be tested on one side only.3.6 AccessAll personnel in the C-23 laboratory should be preauthorized by the facultysupervisor or under the supervision of authorized personnel (lab technicianor teacher assistant). No person other than the faculty supervisor orspecifically authorized personnel, are permitted to make alterations to, or runexperiments with the hardness testers.3.7 TrainingAll individuals using the hardness testers shall be required to receive trainingin the proper operation and maintenance of the hardness tester and itscontrols. Training will include such topics as the complete operation andcontrol of the hardness tester. Training programs shall be administered onlyby qualified personnel at UNB.18

3.8 Personal Protective EquipmentFollowing personal protective equipment is mandatory while using thehardness testers: Safety gogglesSee figure below for description of safety equipment.Figure 12: CLARK CR - 8 Hardness Tester Dust Cover and safetygoggles19

4. Operation4.1 Qualified PersonnelThese notes in the operation section will provide a guideline to theindividual who has been trained by qualified personnel to operate all modelsof hardness testers. Only after the individual has been trained and feelsconfident with the hardness tester operating procedure should he attempt tooperate the hardness tester by using these notes. Do not proceed if you arenot properly trained or are unsure in any manner of the safe operation andsafety concerns of this equipment.4.2 Experiment preparationFollowing steps should be carried out to prepare for the experiment: Ensure that the system’s physical integrity is not compromised(cracked, broken or failed components on the hardness tester). Double check that the proper weight is suspended for the scale thatyou desire and that the proper penetrator is chosen. Ensure that there is sufficient oil in the dashpot of the CLARKhardness tester and in the oil reservoir of PITTSBURGH Brinellhardness tester to provide lubrication to the moving components. TheWILSON 103 R does not require oil for its moving components. On the CLARK hardness tester models, ensure that the knurledscrew is not already turned out. The knurled screw controls thespeed of application of the major load/static load on the specimenmaterial. The operating handle for the CLARK hardness tester models andWILSON 103 R hardness tester should be forward (leaning front)before operating the equipment. Prior to operating the hardness tester, the test specimen should becleaned with oil to clear the specimen of all scratches. This will helpachieve more accurate results. On all the models of hardness testers, mount the required Anvil on theelevating screw and clean the Anvil with some oil to remove20

scratches. This practice will also help achieve more accurateresults. Always wear safety goggles while conducting this experiment.4.3 Lab Instructions4.3.1 Instructor ResponsibilitiesThe SOP of hardness testers should be read and fully understood. Thisdocument provides all the necessary information on the hardness testeroperation, the hazards involved & safety precautions to be taken while usingall models. The lab instructor shall remain in the room while the experimentis in progress. After the students have fully assembled and before anyexplanation has begun, the instructor should relay all safety precautions andhazards as outlined in Section 3. You should inform the students that theymust contact the instructor if any problems or concerns should arise duringthe experiment. Make the group aware of the fire extinguisher locations, firealarm pull station and exits. Any student who is missing his or her personalprotective equipment should not be allowed by the instructor to enter thelaboratory C-23 or proceed with the experiment.4.3.2 Data/Instruments display Locations and FunctionsThe data display instruments and their function is described as follows: Dial indicators - Mounted on the top of CLARK (C 12 - A and CR 8) and WILSON 103 R model) hardness testers - Displays thehardness value of the specimen in different scales (the Large handindicates the hardness value). It also indicates the application of minorload (complete three revolutions of Large hand) by the small hand ofhardness tester touching the red point. (see Figures 12, 14 and 15). Pressure gauge - Mounted on top of PITTSBURGH Brinell hardnesstester - Displays the pressure on penetrator in Kilopascals (see Figurebelow). Test specimens/Testing blocks - Provided with the hardness tester andprotected in a safe case - Used as standard to check the hardness21

testers by comparing the measured hardness value with the hardnessvalue provided on the testing block. Indentation magnification viewer - Provided with the PITTSBURGHBrinell hardness tester – Measures in millimeters the impression madeby penetrator of PITTBURGH hardness tester.Figure 13: PITTBURGH Brinell Hardness Tester Pressure Gauge22

Figure 14: Test specimens, Penetrators and Anvils of HardnessTesters4.4 Operating Procedure4.4.1 Operation of Hardness testersAll the models of hardness testers operate in a similar way but with a fewdifferences. The operation of all the models of hardness testers is discussedbelow as follows:23

a)CLARK (C 12 - A):After preparing for the experiment as mentioned in Section 4.2, follow thesesteps to operate and perform an experiment on this hardness tester:1. Choose the hardness scale for the required hardness value of the testspecimen.2. From the chart that is riveted on the hardness tester, choose theappropriate penetrator and amount of load in Kg for the scale chosen.The chart will also indicate which color scale (Black or Red) to readon the Dial indicator to get the hardness value.3. Elevate the test specimen placed on Anvil by turning the capstan untilit makes contact with the penetrator.4. Continue turning capstan until the large hand on Dial indicator hasmade three complete revolutions, which will also be indicated by thesmall counter hand pointing to the horizontal line. Now the minor loadof 10 Kg is applied to the test specimen. After three revolutions thelarge hand should stop in green colored “SET ZONE” to apply correctminor load of 10 Kg.5. Set the Dial indicator Large hand to the position labeled “SET” OR“ZERO” on the Dial indicator irrespective of the scale ofmeasurement (Black or Red). See the figure below.NOTE: Never move the capstan back to adjust the large zero pointer.Release the load and choose another spot on the sample to test.24

Figure 15: CLARK C 12 - A Hardness Tester Dial indicator6.Trigger the operating lever/handle (Figure 1) of hardness tester toapply major load on the test specimen by pushing it back. When thedial hand comes to rest on the dial indicator, wait 5 seconds to pull theoperating handle/lever to the front. The reading now indicated on thedial indicator is the hardness value measured by the hardness tester ofthe test specimen.NOTE: Even though the user may be using a scale other than “C”, alwaysset “0” on the black “C” scale, then read the hardness value from the desiredscale.25

7.Lower the elevating screw by turning capstan and remove the testspecimen.8.Clean the test specimen and place it back in safe place to preventfrom corrosion and scratches on its surface.Figure 16: CLARK C 12 - A Hardness scale selection chart26

Refer to Appendix “B” (CLARK Hardness tester, Follow these simpleoperating directions) to see the description of operating procedure.b)CLARK CR - 8:The operating procedure for CLARK CR - 8 hardness tester is thesame as CLARK C 12 - A. Please see Figure 6 to see the scaleselection chart and Figure 17 to see the dial indicator for this model ofhardness tester.Figure 17: CLARK CR - 8 Hardness tester dial indicator27

Please refer to Figures 5, 6 and 7 to see the components of this modelof hardness tester while following this operating procedure. For thismodel of hardness tester follow Step 4 of the operating procedure ofthe C 12 - A hardness tester. It is necessary for the Large hand of Dialindicator to fall in a SET zone between 11’o clock and 1’o clock onthe Dial indicator. It is best if the user sets it to 12’o clock. The pointlabeled as “C” on the dial indicator in Figure 17 is the SET point forthis hardness tester model after three complete revolutions(application of minor load) of the Large hand. So in step 5, set theLarge hand of dial indicator at “C” irrespective of the scale ofmeasurement (Red or Black). Follow the operating instructions of C12 - A model for the rest of the experiment.NOTE: Never move the capstan back to adjust the large zeropointer. Release the load and choose another spot on the sample totest.c)WILSON 103 R:The operating procedure for WILSON 103 R model is the same as theCLARK hardness tester models. Please refer to Figures 8 and 9 to see thedescription of components of WILSON 103 R model and follow theoperating procedure of CLARK hardness tester. Please refer to Figures 18and 19 to see the description of scale selection chart and dial indicator forthis model of hardness tester.This model is more user friendly as the major load can be changed byturning the static weight adjusting dial clockwise. To select the weight, turnthe dial clockwise until the Red dot lines up with the desired numerical valueof weight. Never turn the dial counterclockwise, especially when theoperating handle is leaning in a forward direction (see Figures 8 and 9). Doso, can cause equipment failure.28

Figure 18: WILSON 103 R Hardness tester dial indicatorFor this hardness tester, completion of three complete revolutions of largehand of dial indicator is indicated by the small counter hand touching the redpoint. After application of the minor load, the large hand is set to the pointlabeled as “C” as it was in CLARK CR - 8 model.29

Figure 19: WILSON 103 R Hardness tester dial indicatord)PITTSBURGH Brinell hardness tester 1862:After preparing for the experiment as mentioned in section 4.2, follow thesesteps to operate and perform experiment on this hardness tester: Turn the capstan and keep raising the elevating screw until the testspecimen is in contact with the penetrator of hardness tester. Ensure that the knurled screw (see Figure 10) is screwed tightly andturned fully clockwise so that moving the operating handle up anddown develops pressure on the penetrator. Move the operating handle up and down until the pressure gaugeindicates the desired pressure.30

Maintain the desired pressure for about 10 - 15 seconds by holding theoperating handle. Release the operating handle and unscrew the knurled screw torelease the pressure. Lower the elevating screw by turning capstan and remove the testspecimen from the anvil. Measure the diameter of indentation on the test specimen by using theindentation magnification viewer. See the scale “BRINELL” hardness value corresponding to thatmeasured indentation diameter. Now see the hardness values on other scales corresponding to thisvalue on the “BRINELL” scale. Please see Figure 20 for theconversion chart that converts hardness values in different scales fromdiameters of indentation and other measured scales.31

Figure 20: Hardness scales conversion chart4.4.2 ShutdownThe shutdown procedure of all the hardness testers is identical: Clean the test specimen and Anvil of the hardness testers to removeany scratches after completing the experiment. Place the test specimen and anvils back in their cases after testingthem, to protect them from corrosion and grit.32

5.0 Inspection and MaintenanceInspections at regular intervals will be performed on all the hardness testersto ensure that they are kept in a safe and well maintained condition. Theinspection and maintenance includes the following: A weekly inspection of the elevating screw and lubricating byapplying a firm pressure on the anvil at the top and then by turning thecapstan counterclockwise until all of the telescoping covers are even. The oil level in the oil reservoirs of CLARK and PITTSBURGHhardness testers should be checked and maintained. The tripping mechanism of both models of the CLARK hardnesstesters should be lightly oiled once per month. The testing blocks, penetrators and anvils (see Figure 14) should beinspected monthly for any scratches and protected in a case tomaintain them in good testing condition.5.1 Periodic & Operational InspectionsVisual inspections are the responsibility of the person who is conductingexperiments on a regular basis with the hardness testers and should becarried out everytime before operating the apparatus. A complete periodicinspection of the apparatus shall be performed by the person who isconducting experiments on a regular basis with this apparatus. That sameperson is required to alert the faculty supervisor of any deficiencies in theapparatus. Deficiencies such as those listed below shall be examined duringboth the periodic & operational inspection. The faculty supervisor willdetermine if the deficiencies will affect the safe operation of the apparatus.a.b.c.d.Dial indicators and tripping mechanism.Worn or corroded static weights/major load.Cracked or corroded hardness tester surface.The test specimen/testing blocks are corroded or their surfaces arecracked.33

6.0 Typical TestsThe actual test procedure will be outlined in the lab script as issued by theprofessor. A typical test includes measuring the hardness value of differentspecimen materials. A typical field note sheet that can be used with hardnesstesters is found in Appendix ‘A’.34

Appendix ‘A’35

Appendix ‘B’36

Appendix ‘C’37

Appendix ‘D’38

Appendix ‘E’39

Figure 2: CLARK hardness tester (Model C 12 - A) The metal dust cover covers the dashpot control and the tripping mechanism on the hardness tester. There is also a Dial indicator mounted on the top of the hardness tester that measures and indicate s the hardness value of specimen material. The larger the value is , the greater the hardness