42.105 Basis for selection of sample.§ 42.105 Basis for selection of sample.
(a) Identification of lot. Selection of proper samples requires sufficient information to identify the lot; such information includes, but is not limited to:
(1) The lot size (see § 42.103 for restriction on small lots);
(2) The type and size of container;
(3) The code marks or other identification marks and the number of containers represented by each mark.
(4) The history of the lot regarding previous inspections; and
(5) The inspection status (normal, tightened, or reduced).
(b) Preliminary scanning. Prior to drawing the sample, the lot should be scanned to determine if any segments or portions are abnormal with respect to wet cases, blown cans, top layer rust, leaking bags, etc. If such segments or portions noted are of any consequence, the lot may be rejected for condition of containers without sampling.
(c) Sample size. Determination of the number of containers to check for condition:
(1) Refer to the table in §§ 42.109 through 42.111 (sampling plans) and find where the lot size (number of individual containers) fits into the column headed “Lot Size Ranges.”
(i) Tables I-A (normal), II-A (tightened), or III-A (reduced), as applicable, will apply to origin inspections, unless the contractor requests that corresponding single sampling plans be used.
(ii) The appropriate double sampling plans in Table I will apply to other than origin inspections, unless the contractor requests that corresponding single sampling plans be used.
(2) Select the appropriate sample size for the corresponding lot size range as indicated in the appropriate column headed “Sample Size.”
(3) Lots rejected for unsatisfactory condition of containers may be subsequently sampled after being reconditioned or reworked. Such lots or resulting portion of a lot may be sampled as a reoffered lot providing the reoffered portion is separately identifiable. When making such inspections, the appropriate sampling plan for tightened inspection shall be used. Except in the case of an appeal inspection, it is not permissible to reinspect a previously rejected lot until it has been reconditioned or reworked.
(d) Sample selection. Select samples from the lot presented in accordance with either of the following two procedures as may be applicable. (A lot offered for inspection will be accepted or rejected in its entirety with either sampling procedure used to select the sample.)
(1) Proportional random sampling. When the number of codes or other identifying marks within the lot and the approximate number of cases or containers per code are known, select sample units at random within each mark and in a number proportionate to the number of containers represented by such mark.
(2) Simple random sampling. When there are no code or other identifying marks, or when the number of codes or identifying marks within the lot and/or approximate number of cases or containers per mark are not known, select sample units at random from the entire lot.
(e) Maximum sample units per case. If the lot is cased, predetermine the number of containers to draw from each sampled case as well as the position within the case. Do not restrict the sampling to the top or bottom layers or to the corners. The best sample is one selected from all the various positions in the shipping case. It is desirable but not mandatory to limit the number of sample units to a single container from any one case. Multiple sample units may be taken from a single case but not in excess of the following plan:
(1) When containers are packed 12 or less to a case, draw a maximum of 6 sample units from any one case; and
(2) When containers are packed more than 12 to a case but not more than 60, draw a maximum of 12 sample units from any one case; and
(3) When containers are packed more than 60 to a case but not more than 250, draw a maximum of 16 sample units from any one case; and
(4) When containers are packed more than 250 in a case, draw a maximum of 24 sample units from any one case.[31 FR 4687, Mar. 19, 1966, as amended at 36 FR 18456, Sept. 15, 1971. Redesignated at 42 FR 32514, June 27, 1977 and 46 FR 63203, Dec. 31, 1981]