Implement
sampling
procedures
 FDFOPTISP2A
Prepare for sampling
 Identified in accordance with the sampling
plan
 Prepare Sampling equipment, containers
and labels
Collect samples
 Collect samples according to procedures and
the requirements of the sampling plan
•Collect samples taking account of OHS mearures
to contol risk of injury
Control 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
Hierarchy or Preferred Order
of Risk Control
 Elimination  Substitution  Isolation  Engineering Control  Administrative Control -
 Personal Protective Equipment  Basic Priciple
Change work not worker
Manual Powder Sampling
With a range of powder samplers,
you can sample anything from
normal free
flowing powders to cohesive sticky
powders.
Sack Master
The Sack Master has
been specially
designed to take
samples through
the side of a sack.
Manual Liquid Sampling
Sampling with an
Environmental sampelrs
Cream and Paste Sampling
Taking cream and paste samples has
never been easy or quick.
Handle Samples
 Samples must be handled and prepared to
preserve sample and source integrity
 Defects or abnormalities in source material and/or
sample must be identified and reported
 Sample information is to be recorded according to
workplace sample recording requirements
 The workplace must meets housekeeping
standards
Sampling Procedures
 Inspection by Attributes




ISO15378 - GMP
PS9004
EN-ISO 9001 –QMS
Military Standard 105E
Sampling Codes
 BS 6001-1 1999 (ISO 2859-1:1999) Sampling
procedures for inspection by attributes. Part 1:
Sampling schemes indexed by acceptance
quality
limit (AQL) for lot-by-lot inspection.
 ISO 2859-2:1985 Sampling procedures for
inspection by attributes. Sampling plans indexed
by limiting quality (LQ) for isolated lot
inspection.
 ISO 2859-0:1995 - Part 0: Introduction to the
ISO 2859 attribute sampling system.
Sampling procedures - Inspection by Attributes –
p.2/23
ISO 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 process
average at least as good as the specified
acceptance AQL, whilst at the same time
providing an upper limit for the risk to the
consumer of accepting the occasional poor lot.
 Applicable to end products, raw materials,
operations, maintenance operations,
administrative procedures.
Usage 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 a
deterioration in quality be detected.
– an incentive to the supplier to reduce
inspection costs should consistently good
quality be achieved.
 Can also be used for inspection of lots in
isolation.
Terminology
 Inspection by attributes: inspection
where an
item is classified as conforming or
nonconforming with respect to a specified
requirement or set of requirements.
 Nonconformity: Non fulfillment of a specified
requirement. Usually classified according to the
degree of seriousness. More serious
nonconformities will usually be assigned a very
small AQL, whilst less serious nonconformities
will be assigned higher AQL values.
Terminology (cont)
 Normal inspection: Use of a sampling plan with
acceptance criteria devised to secure the producer
a high probability of acceptance when the process
average of the lot is better than the AQL. Used
when there is no reason to suspect the process
average differs from an acceptable level.
 Tightened inspection: Use of a sampling plan
with an acceptance criteria that is tighter than that
for the corresponding plan for normal inspection.
Invoked when the inspection results of
consecutive lots indicate that the process average
might be poorer than the AQL.
Terminology (cont)
 Acceptable Quality Limit (AQL): Quality level
that is the worst tolerable process average when
a
continuing series of lots is submitted for
acceptance sampling. AQL does not mean
’desirable level’. ISO 2859 is designed to
encourage suppliers to have process averages
consistently better than the AQL, otherwise
thereis a risk of switching to tighter inspection.
Terminology (cont)
 The designation of an AQL does not imply that
the supplier has the right knowingly to supply
any
nonconforming items:
 AQL values shall not exceed 10%
nonconforming.
 When the quality level is expressed as number of
nonconformities per 100 items, AQL values up to
1000 nonconformities per 100 items may be
used.
Sampling:
– Sample selection must be drawn from the lot
by simple random sampling.
– When double or random sampling is to be
used, each subsequent sample shall be
selected from the remainder of the same lot.
Inspection Levels
 4 special inspection levels - S1, S2, S3, S4.
 3 general inspection levels - I, II, III.
 Special inspection levels used when sample size
must be kept small and larger sampling risks can
be tolerated.
 Level II will be used unless another inspection
level is specified.
 Level I is used when less discrimination is
required, Level III when greater discrimination is
required.
Sample size code letters
Sample size code letters
(cont)
Single Sampling Plans
Double Sampling Plans
 Normal Inspection
OC Curves
 Operating Characteristic Curves
– OC curve is a graph showing what any particular
sampling plan can be expected to do in terms of
accepting and rejecting batches.
– An understanding of the implications of an OC
curve helps understand the risks to the
manufacturer, consumer, and in deciding
inspection levels and batch sizes.
– Each possible plan has its own OC curve.
– Horizontal scale - shows the percentage defective.
Vertical scale - shows the percentage of batches
that may be expected to be accepted if
batches are
produced with that percentage of defects.
Using an OC curve
Interpret the curve according to this example:
•If the lot quality is 0.093 fraction defective, then the
probability of acceptance, Pa, is 0.05.
•If the lot quality is 0.018 fraction defective, then the
probability of acceptance, Pa, is 0.95.
Alternative 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.
OC Curves
OC Curve Example





Code Letter M
AQL 1.5
Sample size - 315
Accept: 10, Reject: 11
What happens if a batch with 3% defectives is
submitted ?
 Find 3% on the X axis, and follow a vertical line
up until it meets the 1.5% curve.
 Take a horizontal line across to the Y axis, and
read off the value of 65%.
 I.e., 65% of batches would be accepted and 35%
rejected.
More OC curve examples
Statistical Quality Control Online
 http://iew3.technion.ac.il/sqconline/milstd105
.html
 This application gives the single and double
sampling plans for attributes, according to
the Military Standard 105E tables, for a
given lot size and AQL
Example of Online Calculation
Result Single sampling
The Double sampling
Results
Even gives the OC curve
 The OC curve
describes the
probability of
accepting a
lot, OC(p), as
a function of
the proportion
nonconforming
(p),
Concrete examples
 EN 455 Part 1 for medical gloves - Pinholes
– General inspection level 1, AQL 1.5%.
– Minimum sample size code letter L (200
gloves)
– If a batch with 3% pinholes is submitted,
there is a 75% chance of them being accepted.
 All Wales Universal Container contract
– Agreed AQL of 0.65%, general Inspection
level I.
– Sample code L (200 samples).
– If a batch with 5% leakers is submitted, there
is a 99% chance of them being rejected.
Setting an Inspection Level
 Select the required AQL (as an average).
 Decide what quality should have a high
chance of
rejection.
 Choose the appropriate sampling plan by
inspecting the OC curves.
Setting an Inspection Level
 Example
 An 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.
Switching Rules
 Normal 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 the
number 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.
Switching Scores
 Single Sampling Plans
 Used 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 switching
score if the lot would have been accepted if the AQL had been
one step tighter; otherwise reset score to 0.
 When the acceptance number is 0 or 1, add 2 to the switching
score if the lot is accepted; otherwise reset score to 0.
 As in the previous slide, when the switching score is at least 30
and production is at a steady state, switch to reduced
inspection if
considered desirable by the responsible authority.
Important points
 Setting an AQL does not guarantee to the
customer that batches of a worse quality will not
be accepted.
 If the average quality of batches being submitted
are a little worse than the AQL, a number of
batches will probably be accepted before a switch
to tightened inspection is called for.
 In general, the customer gets a quality which is,
on average, better than the AQL, since the tables
are arranged to provide an economic incentive the manufacturer cannot afford to have more than
a small proportion of batches rejected, and so will
improve the quality if this proportion is exceeded.