_2.214c 2.214d .2.214e Determination of the total length at a different tension and/or method of support, for a tape not exceeding 200 ft or 50 m in length; tension and method of support should be specified by the customer. Determination of the length of a subinterval under the same conditions used for determination of the total length; subinterval must be specified. Determination of the length of a subinterval under a different tension and/or method of support than used to determine total length; interval, tension, and method of support must be specified. 2.214f Determination of the tension at which the length of an interval most nearly gives its designated length, for a tape not exceeding 200 ft or 50 m in length; interval and method of support must be specified. .2.214g 2.214h .2.214i Determination of the average weight per unit length of a tape ribbon. Determination of the average AE value for a tape ribbon. The AE value is the product of the average cross-sectional area of the tape ribbon and its Young's Modulus of Elasticity. Computation of length and/or tension value derived from the above test items. 2.214j Handling charge for each tape sent without reel. 2.214z Special measurements not covered by this schedule. 212.215 Invar tapes. (a) The word Invar* is used for the designation of an ironckel alloy having a very low coefficient of thermal expansion, about 1/25 I that for ordinary steel. Consequently, Invar* tapes are used for highly curate long-interval length measurements in uncontrolled temperature vironments. a (b) Invar* tapes accepted for calibration will be issued port of Calibration and be assigned an NBS serial number for entification. The length intervals reported will be for measurements de with tapes supported at specified points in the same horizontal plane, der specified applied tension, and at 20 °C (68°F). Thermometers can be tached to the tape when their weight and location are indicated. rmally, the accuracy of the reported lengths will be one part in 500,000 0.00002 m (0.00007 ft), whichever is larger, except when determined der item 212.215e and f. 'rademark: Société Métallurgique d'Imply, June 17, 1907. 212.215a 212.215b 212.215c 212.215d 212.215e 212.215f 212.215g 212.215h 212.215i Determination of the total length of a tape in catenary suspension at one tension, for a tape not exceeding 250 ft or 75 m in length. Tension and points of support must be specified. Determination of the total length at another tension and/or catenary suspension, for a tape not exceeding 250 ft or 75 m in length. Tension and points of support must be specified. Determination of the total length when supported on a horizontal flat surface under the same tension applied in either test items 212.215a or b. Item 212.215g is also required for this test. Determination of one specified subinterval in a group of uniformly spaced intervals of the total length when supported on a horizontal flat surface under the same tension applied test item 212.215c. in one Determination of the total length to +0.001 ft (0.0003 m) or Tension must be specified or may be adjusted to that at which the length of the interval most nearly approaches its designated length. Determination of the length of another interval to +0.001 ft (0.0003 m) or one part in 100,000, whichever is greater, at one method of support under one tension, for a tape not exceeding 200 ft or 50 m in length. Interval, method of support, and tension must be specified or the tension may be adjusted to that at which the measured length of the interval most nearly approaches its designated length. Determination of the average weight per unit length of a tape ribbon. Determination of the average AE value for a tape ribbon. The AE value is the product of the average cross-sectional area of the tape ribbon and its Young's Modulus of Elasticity. Determination of the thermal expansion of the tape ribbon to +0.000002 m/1 °C from about 10 to 40 °C (50 to 104 °F). Item 212.215g is required with this test. 2.215j Computation of length and/or tension value derived from the above test items. 2.215k Handling charge for each tape sent without reel. 12.215z Special measurements not covered by this schedule. 212.216 Surveying instruments (other than tapes). Item Description 12.216a Leveling rod-determination of the lengths for the principal onemeter intervals to ±0.0001 m when resting in. a horizontal position. 12.216b Spring balance-determination of balance reading for 5-pound of loading when placed in a horizontal position, as increments in applying tensions to tapes. 12.216z Special measurements not covered by this schedule. ieve 212.217 Sieves. The precision seal of the National Bureau of Standards on any indicates that the sieve has been tested at the Bureau and found to onform to specification. Except by special arrangements, the testing of ieves at the Bureau is limited to No. 31⁄2 to No. 400, inclusive. Each haemacytometer chamber and each cover glass which conforms o the specification is marked with a National Bureau of Standards recision seal. In general, work will be discontinued when a substantial umber of items in a lot fail to comply with specifications and the fee ill be computed on the basis of the number of items tested plus a special andling charge. Items 212.218a to e, inclusive, will be applicable if a inimum of 12 chambers are submitted at one time; otherwise item 212.2182 ill be applicable. Only letter reporting results of test will be upplied for any one test at the prices of items 212.218a to e, inclusive. 212.218a 212.218b 212.218c 212.218d 212.218e 212.218z Single Neubauer haemacytometer chamber-testing single cell Single Fuchs - Rosenthal haemacytometer chamber Double Neubauer haemacytometer chamber-testing double cell Double Fuchs - Rosenthal haemacytometer chamber-testing double cell chamber (having two Fuchs-Rosenthal rulings) and two cover glasses for conformity with specification. Quadruple haemacytometer chamber-testing quadruple cell chamber (having two Neubauer rulings and two Fuchs-Rosenthal rulings) and two cover glasses for conformity with specification. Special measurements not covered by this schedule. 212.219 Precision circles. 212.219z Special measurements only are conducted in this category. Engineering Metrology 212.220 General. (a) Direct inquiries to: Engineering Metrology Section, MET A107, National Bureau of Standards, Washington, DC 20234. Telephone: 301921-2126. Mark shipments for the attention of: Engineering Metrology Section, MET A107, National Bureau of Standards, Route 70S and Quince Orchard Road, Gaithersburg, Maryland 20760. (b) The dimensional unit referenced in engineering metrology is the national standard inch, equal to exactly 0.0254 meter, the meter being defined in Section 200.102. For controlling dimensions in the manufacture of all products, various types of dimensional gages are used. Gages which are used for precise size control of critical dimensions are measured in our laboratories as a service to the public. The wide variety of such gages measured includes end standards for length, cylindrical plug and ring gages and balls for diameter, and screw thread gages and master gears for those more complex dimensional requirements. Angle gage blocks, polygons, angular indexing tables, and other such items are calibrated for ntrolling angular dimensions. In addition various instruments, measuring ols, and accessories are calibrated, such as optical flats for measuring atness, surface roughness specimens for calibrating measuring struments, cylinders used for the measurement of threads crometer and vernier calipers for measuring measuring size, and ecialized components. Consultation services with respect to dangular measuring problems are available also. and gears, many other dimensional if (c) Schedules 212.221 to 212.229 include a statement of the lative accuracy to which measurements ordinarily are made. However, character of the defining surfaces of a gage or other article does not rrant the measurement to this accuracy, the report will show the accuracy tually obtained. If a greater accuracy is requested and the defining rfaces permit measurements to the accuracy requested, the necessary asurements will be made as a special test. The minimum fee for any libration or test work on one order at one time is $25. (d) In addition to the items covered by schedules 212.221 to 2.229, occasionally other items such as gage block accessories, gill net ges, and Knoop indenters are calibrated. Sizes other than those listed the fee schedules also are calibrated on special request. For libration in quantity for items of one size at one time, a reduced lot e may be quoted upon request. (e) In the shipment of gages, extreme precautions should be ken against both corrosion and damage by contact with other gages during ansit. All defining steel surfaces should be greased and protected with inhibiting paper or a suitable strippable plastic coating. A greased eel surface coming in contact with newspaper, untreated wrapping paper, excelsior is very likely to corrode. Small gages suitably wrapped may fastened in place in a strong container so that no movement is possible. ug and ring gages ordinarily should not be shipped mated. In the case of rge-size threaded plugs and rings, however, mating is permissible as a ans of protecting the plug threads. In such cases a grease must be used at will prevent corrosion between the mating gages. (f) For shipments from countries other than the United States, e owner of gages which are to be transported by ship to the National reau of Standards for test must make prior arrangements with a customs oker either in the country of origin or in the United States for entry of e gages, with or without bond as may be necessary, and prepaid ansportation to and from the ports of entry and exit. Entry in bond is quired for gages made outside of the United States; whereas gages made in e United States may be entered without bond. If arrangements are made th a broker in the country of origin the broker should, in turn, have a stoms broker in or near the port of entry arrange for entry of the gages d transportation to the National Bureau of Standards, Gaithersburg, ryland. Direct arrangements can be made with customs brokers located shington, DC. These brokers will arrange for entry of the gages, prepaid ansportation from the port of entry to the Bureau, and transportation to port of exit after measurements have been completed. commendation does not preclude the use of customs brokers at ports such Baltimore, Maryland or New York, New York if such an arrangement is eferred by the owner of the gages. An alternative method of shipment e in This ich eliminates the need for the services of a customs broker is by air eight to the National Bureau of Standards, Washington National Airport, shington, DC. When shipments are made by this method the Bureau will ck up the gages at the airport, arrange for entry in bond when necessary, d after test obtain release from bond if required and deliver the gages the airport for return shipment. The gages will be returned collect |