Introduction A Class F field standard weight (after this, called “weight”) is intended to be used primarily to test commercial weighing devices for compliance with the requirements of NIST Handbook 441. Class F weights may be used to test most accuracy Class2 III scales, all scales of Class IIIL or IIII, and scales not marked with a class designation. A weight shall be verified to be within-tolerance prior to use, The within-tolerance status of a weight shall be rechecked as often as regulations or circumstances require, especially when damage to it is known or suspected. General These specifications apply to new weights placed in service after the publication of this standard; the tolerances apply to all weights in service. A weight in service prior to the publication of this standard that has maintained Class F tolerances between verifi cation tests shall continue to be acceptable. The specifications permit the use of a weight at its nominal value in normal testing operations, where the tolerance on the item under test is at least three times as great as the tolerance of the weight3. A partial list of specifications from Handbook 105-1 1. Material 1.1 A weight made of brass or a fabricated weight (such as a laminated weight or a weight of non uniform density) shall not be placed in service after the publication date of this standard (1990). 1.2 A weight smaller than 5 grams/0.01 lb shall be constructed of stainless steel, tantalum, nickelchromium alloy, aluminum alloy, or other material sufficiently resistant to corrosion and oxidation that the surface need not be protected or coated. 1.3 A weight of 5 grams/0.01 lb up to and including 5 kg/10 lb shall be constructed of material having a hardness of Rockwell B 80 or greater (such as 300-series stainless steel), and be resistant to abrasion, corrosion, denting, and chipping. 1.4 A weight larger than 5 kg/10 lb shall be constructed of materials such as iron, steel, or stainless steel, have a hardness of Rockwell B 80 or greater, and be resistant to abrasion, corrosion, denting, and chipping. Cast iron may be used for weights 10 kg/20 lb and larger. Body filler (e.g., fiberglass, putty, or plaster) shall not be used to correct a poor casting or finish. Finish 2.1 The surface finish of a new weight machined from round bar stock shall have a roughness average of 0.80 micrometers (32 microinches) or better, determined by use of a hand-held surface rough ness indicator (available from several manufacturers) or more accurate method, and be free of scratches, dents, and chipped corners or edges, determined by visual examination. A beaded or blasted fi nish (with roughness average 1.25 micrometers (50 microinches) or better) is acceptable on a cube weight to facilitate gripping. 2.2 A weight 5 kg/10 lb or less shall not have a surface coating. 2.3 A weight larger than 5 kg/10 lb constructed of materials susceptible to corrosion or tarnishing shall have a protective surface coating. A light coat of sprayed-on fl at aluminum paint is recommend ed. Lacquer is also acceptable. Epoxy paint or plated surfaces are not acceptable. A coating is recommended for the bottom of a weight, particularly if the bottom is recessed. If paint or lacquer is used, it shall be hard and resistant to chipping. Cast metric and avoirdupois field standards shall be color coded (i.e. gold for metric and silver for avoirdupois) to differentiate the weights.
Model Weight Type 12499 1 g Cylindrical 12501 2 g Cylindrical 12503 5 g Cylindrical 12505 10 g Cylindrical 12523 20 g Cylindrical 12525 30 g Cylindrical 12527 50 g Cylindrical 12507 100 g Cylindrical 12549 150 g Cylindrical 12509 200 g Cylindrical 12529 300 g Cylindrical 12511 500 g Cylindrical 12513 1 kg Cylindrical 12515 2 kg Cylindrical 12517 3 kg Cylindrical 12519 4 kg Cylindrical 12521 5 kg Cylindrical