2Prepare for sampling Identified in accordance with the sampling plan Prepare Sampling equipment, containers and labels
3Collect samplesCollect samples according to procedures and the requirements of the sampling planCollect samples taking account of OHS mearuresto contol risk of injury
4Control of Occupational Injury The control of occupational injury and disease risks should preferably be dealt with in a preferred order or hierarchy.The control measures range from the most effective to the least effective.The Hierarchy or Preferred Order of Control is: next slide
5Hierarchy or Preferred Order of Risk Control Elimination -Substitution -Isolation -Engineering Control -Administrative Control -Personal Protective Equipment -Basic PricipleChange work not worker
6Manual Powder Sampling With a range of powder samplers,you can sample anything from normal freeflowing powders to cohesive sticky powders.
7Sack Master The Sack Master has been specially designed to take samples throughthe side of a sack.
8Manual Liquid Sampling Sampling with an Environmental sampelrs
9Cream and Paste Sampling Taking cream and paste samples hasnever been easy or quick.
12Handle SamplesSamples must be handled and prepared to preserve sample and source integrityDefects or abnormalities in source material and/or sample must be identified and reportedSample information is to be recorded according to workplace sample recording requirementsThe workplace must meets housekeeping standards
13Sampling Procedures Inspection by Attributes ISO15378 - GMP PS9004 EN-ISO 9001 –QMSMilitary Standard 105E
14Sampling Codes BS 6001-1 1999 (ISO 2859-1:1999) Sampling procedures for inspection by attributes. Part 1:Sampling schemes indexed by acceptance qualitylimit (AQL) for lot-by-lot inspection.ISO :1985 Sampling procedures forinspection by attributes. Sampling plans indexedby limiting quality (LQ) for isolated lotinspection.ISO : Part 0: Introduction to theISO 2859 attribute sampling system.Sampling procedures - Inspection by Attributes – p.2/23
15ISO 2859 Part 1 Acceptance sampling system for inspection by attributes.It is indexed in terms of acceptance quality level(AQL)Aim - to induce a supplier to maintain a processaverage at least as good as the specifiedacceptance AQL, whilst at the same timeproviding an upper limit for the risk to theconsumer of accepting the occasional poor lot.Applicable to end products, raw materials,operations, maintenance operations,administrative procedures.
16Usage of the Part 1 scheme. Intended to be used for a continuing series of lots,which will allow the application of switching rules.The rules provide:protection to the consumer should adeterioration in quality be detected.an incentive to the supplier to reduceinspection costs should consistently goodquality be achieved.Can also be used for inspection of lots inisolation.
17Terminology Inspection by attributes: inspection where an item is classified as conforming ornonconforming with respect to a specifiedrequirement or set of requirements.Nonconformity: Non fulfillment of a specifiedrequirement. Usually classified according to thedegree of seriousness. More seriousnonconformities will usually be assigned a verysmall AQL, whilst less serious nonconformitieswill be assigned higher AQL values.
18Terminology (cont) might be poorer than the AQL. Normal inspection: Use of a sampling plan withacceptance criteria devised to secure the producera high probability of acceptance when the processaverage of the lot is better than the AQL. Usedwhen there is no reason to suspect the processaverage differs from an acceptable level.Tightened inspection: Use of a sampling planwith an acceptance criteria that is tighter than thatfor the corresponding plan for normal inspection.Invoked when the inspection results ofconsecutive lots indicate that the process averagemight be poorer than the AQL.
19Terminology (cont) Acceptable Quality Limit (AQL): Quality level that is the worst tolerable process average when acontinuing series of lots is submitted foracceptance sampling. AQL does not mean’desirable level’. ISO 2859 is designed toencourage suppliers to have process averagesconsistently better than the AQL, otherwise thereis a risk of switching to tighter inspection.
20Terminology (cont) The designation of an AQL does not imply that the supplier has the right knowingly to supply anynonconforming items:AQL values shall not exceed 10%nonconforming.When the quality level is expressed as number ofnonconformities per 100 items, AQL values up to1000 nonconformities per 100 items may be used.
21Sampling: Sample selection must be drawn from the lot by simple random sampling.When double or random sampling is to beused, each subsequent sample shall beselected from the remainder of the same lot.
22Inspection Levels 4 special inspection levels - S1, S2, S3, S4. 3 general inspection levels - I, II, III.Special inspection levels used when sample sizemust be kept small and larger sampling risks canbe tolerated.Level II will be used unless another inspectionlevel is specified.Level I is used when less discrimination isrequired, Level III when greater discrimination isrequired.
27OC Curves that may be expected to be accepted if batches are Operating Characteristic CurvesOC curve is a graph showing what any particularsampling plan can be expected to do in terms ofaccepting and rejecting batches.An understanding of the implications of an OCcurve helps understand the risks to themanufacturer, consumer, and in decidinginspection levels and batch sizes.Each possible plan has its own OC curve.Horizontal scale - shows the percentage defective.Vertical scale - shows the percentage of batchesthat may be expected to be accepted if batches areproduced with that percentage of defects.
28Using an OC curve Interpret the curve according to this example: If the lot quality is fraction defective, then the probability of acceptance, Pa, is 0.05.If the lot quality is fraction defective, then the probability of acceptance, Pa, is 0.95.
29Alternative OC for Sample plans You can use oc-curves to compare alternative plans.Choose between the plans by their relative ability to detect rejectable lots.You should expect that the steeper the curve, the larger the sample size.
31OC Curve Example Code Letter M AQL 1.5 Sample size - 315 Accept: 10, Reject: 11What happens if a batch with 3% defectives issubmitted ?Find 3% on the X axis, and follow a vertical lineup until it meets the 1.5% curve.Take a horizontal line across to the Y axis, andread off the value of 65%.I.e., 65% of batches would be accepted and 35%rejected.
38Even gives the OC curveThe OC curve describes the probability of accepting a lot, OC(p), as a function of the proportion non- conforming (p),
39Concrete examples EN 455 Part 1 for medical gloves - Pinholes General inspection level 1, AQL 1.5%.Minimum sample size code letter L (200gloves)If a batch with 3% pinholes is submitted,there is a 75% chance of them being accepted.All Wales Universal Container contractAgreed AQL of 0.65%, general Inspectionlevel I.Sample code L (200 samples).If a batch with 5% leakers is submitted, thereis a 99% chance of them being rejected.
40Setting an Inspection Level Select the required AQL (as an average).Decide what quality should have a high chance ofrejection.Choose the appropriate sampling plan byinspecting the OC curves.
41Setting an Inspection Level ExampleAn AQL of 1.5% defective items has been chosen.It is desired to have at least an 80% chance of rejecting a 6% defective batch under normal inspection.Code letters A->J fail to meet the requirement.Code letter K almost meets it, codes L-P more than meet it.Decide the batch size. If batch size is 1000, check sample size code letters table - we can use general inspection level III.The sampling plan would therefore be AQL=1.5%, General Inspection Level=III.
42Switching RulesNormal to tightened: Shall be implemented as soon as two out of five (or fewer than five) consecutive lots have been non-acceptable on original inspection.Tightened to normal: Shall be reinstated when five consecutive lots have been considered acceptable on original inspection.Normal to reduced: implemented when the switching score is at least 30, production is at a steady state, and reduced inspection is considered desirable by the responsible authority.Discontinuation of inspection: is implemented when thenumber of lots not accepted in a sequence of consecutive lots on original tightened inspection reaches 5.Reduced to normal: if a lot is not accepted or irregular/delayed production.
43Switching ScoresSingle Sampling PlansUsed when deciding whether to switch to reduced inspection.Set switching score to 0 at start of normal inspection.Score updated following the inspection of each lot.When the acceptance number is >= 2, add 3 to the switchingscore if the lot would have been accepted if the AQL had beenone step tighter; otherwise reset score to 0.When the acceptance number is 0 or 1, add 2 to the switchingscore if the lot is accepted; otherwise reset score to 0.As in the previous slide, when the switching score is at least 30and production is at a steady state, switch to reduced inspection ifconsidered desirable by the responsible authority.
44Important points Setting an AQL does not guarantee to the customer that batches of a worse quality will notbe accepted.If the average quality of batches being submittedare a little worse than the AQL, a number ofbatches will probably be accepted before a switchto tightened inspection is called for.In general, the customer gets a quality which is,on average, better than the AQL, since the tablesare arranged to provide an economic incentive -the manufacturer cannot afford to have more thana small proportion of batches rejected, and so willimprove the quality if this proportion is exceeded.