Precision Analytical Masses (Ultra Class) is recognized by the National Institute of Standards and Technology (NIST), the American Society for Testing and Materials (ASTM) and the International Organization of Legal Metrology (OIML) for its precision weights and mass standards. The weights can range from the very precise, highly polished one and two-piece stainless-steel weights to 5,000 lb. cast-iron weights.

To maintain lab precision, it is necessary to perform routine calibrations and verifications using analytical masses and calibrating weights.

Like ASTM classes 0,1,2,3, these ultra-class weights meet or exceed specifications as defined in the ANSI/ASTM E617 standard. UltraClass weights are the most precise two-piece weights offered, with a weight tolerance 50% greater than ANSI/ASTM Class 1 weights.

UltraClass weights are unique in that they offer extremely high precision while still maintaining the advantage of a two-piece construction (like ASTM classes 0-4). One-piece constructions are often needed to be replaced or grinded and polished manually to make adjustments due to the single, uniform piece of raw material.

These weights are highly resistant to corrosion thanks to an alloyed stainless steel and among the finest in state primary standards for manufacturing. They are manufactured from the highest quality stainless steel alloy–blending controlled density, low magnetic susceptibility, stability and anti-corrosion.

These precision weights are 1 g and larger and are produced from two pieces of material: the body of the weight and the knob of the weight. This lifting knob is specifically designed for use with forceps, tweezers, and other lifting devices. The knob has a thread that screws directly into the body and is tightened. The weights are easy to recognizable as the top of the weight is marked with a nominal value.

Key Features

• ASTM internationally recognized weight specifications
• Two-piece construction despite high precision
• All surfaces polished to a mirror-like finish