FUNDAMENTAL CONSIDERATIONS ASSOCIATED WITH THE ENFORCEMENT OF SPECIFICATIONS, TOLERANCES AND REGULATIONS 1. UNIFORMITY OF REQUIREMENTS 1.1. NATIONAL CONFERENCE CODES.-Weights and measures jurisdictions are urged to promulgate and adhere to the National Conference codes, to the end that uniform requirements may be in force throughout the country. This action is recommended even though a particular jurisdiction does not wholly agree with every detail of the National Conference codes. Uniformity of specifications and tolerances is an important factor in the manufacture of commercial equipment. Deviations from standard designs, to meet the special demands of individual weights and measures jurisdictions, are expensive, and any increase in costs of manufacture is, of course, passed on to the purchaser of equipment. On the other hand, if designs can be standardized by the manufacturer to conform to a single set of technical requirements, production costs can be kept down, to the ultimate advantage of the general public. Moreover, it seems entirely logical that equipment that is suitable for commercial use in the "specification" States should be equally suitable for such use in other States. Another consideration supporting the recommendation for uniformity of requirements among weights and measures jurisdictions is the cumulative and regenerative effect of the widespread enforcement of a single standard of design and performance. The enforcement effort in each jurisdiction can then reinforce and support the enforcement effort in all other jurisdictions. More effective regulatory control can be brought about, and this result can actually be realized with less individual effort, under a system of uniform requirements, than under a system in which even minor deviations from standard practice are introduced by independent State action. 7 Since the National Conference codes represent the majority opinion of a large and representative group of experienced regulatory officials, and since these codes are recognized by equipment manufacturers as their basic guide in the design and construction of commercial weighing and measuring equipment, the acceptance and promulgation of these codes by each State is strongly recommended. 1.2. FORM OF PROMULGATION.-A convenient and very effective form of promulgation already successfully used in a considerable number of States is promulgation by citation of National Bureau of Standards Handbook 44. It is especially helpful when the citation is so made that, as amendments are adopted from time to time by the National Conference on Weights and Measures, these automatically go into effect in the State in question without the need for further promulgation by the State regulatory authority. For example, the following form of promulgation has been used successfully, and is recommended for consideration: The specifications, tolerances, and regulations for commercial weighing and measuring devices, together with amendments thereto, as adopted by the National Conference on Weights and Measures, recommended by the National Bureau of Standards, and published in National Bureau of Standards Handbook 44 and supplements thereto, or in any publication revising or superseding Handbook 44, shall be the specifications, tolerances, and regulations for commercial weighing and measuring devices in the State of [insert name of State]. In some States it is preferred to base technical requirements upon specific action of the State legislature, rather than upon an act of promulgation by a State officer. The advantages cited above may be obtained and may yet be surrounded by adequate safeguards to insure proper freedom of action by the State enforcing officer, if the legislature adopts the National Conference requirements by language somewhat as follows: The specifications, tolerances, and regulations for commercial weighing and measuring devices, as recommended by the National Bureau of Standards, shall be the specifications, tolerances, and regulations for commercial weighing and measuring devices of the State of [insert name of State], except insofar as specifically modified, amended, or rejected by a regulation issued by the State [insert title of enforcing officer). use. 2. TOLERANCES FOR COMMERCIAL 2.1. ACCEPTANCE AND MAINTENANCE TOLERANCES.-The official tolerances prescribed by a weights and measures jurisdiction for commercial equipment are the limits of inaccuracy officially permissible within that jurisdiction. It is recognized that errorless value or performance of mechanical equipment is unattainable. Tolerances are established, therefore, to fix the range of inaccuracy within which equipment will be officially approved for commercial In the case of classes of equipment on which the magnitude of the errors of value or performance may be expected to change as a result of use, two sets of tolerances are established, "acceptance" tolerances and "maintenance" tolerances. Acceptance tolerances are applied to new or newly reconditioned or adjusted equipment and are smaller than (usually one-half of) the maintenance tolerances. Maintenance tolerances thus provide an additional range of inaccuracy within which equipment will be approved on subsequent tests, permitting a limited amount of "deterioration" before the equipment will be officially rejected for inaccuracy, and before reconditioning or adjustment will be required. In effect, there is assured a reasonable period of use for equipment after it is placed in service before reconditioning will be officially required. The foregoing comments do not apply, of course, when only a single set of tolerance values is established, as is the case with such equipment as, for example, glass milk bottles and graduates, which maintain their original accuracy regardless of use, and measure-containers, which are used only once. When tables of tolerances for general weights and measures use are published, if the acceptance and maintenance tolerances differ, it is customary to use the maintenance tolerances for the tabular values, stating the values of the acceptance tolerances in terms of the maintenance tolerances. This is done for convenience of reference by the official, since it is to be expected that he will actually make many more maintenance tests than acceptance tests and so will have more frequent need to use maintenance tolerances than he will to use acceptance tolerances. If maintenance and acceptance tolerances are the same, or if only acceptance tolerances are applicable, the tables are appropriately headed to indicate these facts. 2.2. THEORY OF TOLERANCES.-The theory of tolerances is that their values are so fixed that, on the one hand, permissible errors are kept so small that neither party to a commercial transaction involving the equipment in question will be seriously injured, and that, on the other hand, such a high order of accuracy is not required as to make manufacturing or maintenance costs disproportionately high. Quite obviously, the equipment manufacturer must know what tolerances his product will be required to meet, so that he can manufacture economically. The commercial product must be required to be good enough to satisfy commercial needs, but it should not be required to be made unreasonably costly, complicated, or delicate in order to insure a reduction of its errors to unnecessarily small values. It may well be repeated that manufacturing is simplified and that the level of equipment prices is lowered in proportion to the degree of uniformity among weights and measures jurisdictions in their tolerance requirements and in their specifications for commercial devices. 2.3. TOLERANCES AND ADJUSTMENTS.-There is another aspect of tolerances that merits careful thought; this is the extent to which tolerances should be considered by those persons engaged in the actual adjustment for accuracy of commercial equipment. The ideal situation would be for equipment to be without error. Since it is not practical to require errorless value or performance, a reasonable approximation of this is fixed for enforcement purposes. But, when equipment is being adjusted for accuracy, either initially or following repair or official rejection, the effort should be to adjust as closely as practicable to zero error. Tolerances are primarily accuracy criteria for use by the regulatory official. Equipment owners should never be permitted to take advantage of tolerances by deliberately adjusting their equipment to have a value or to give performance at or close to the tolerance limit. Nor should the repair or service man be permitted to bring equipment merely within tolerance range when, by the exercise of reasonable skill and with the expenditure of a reasonable amount of time and effort, adjustment closer to zero error can be accomplished.' See General Regulation G-R. 4. |