It was a calibration standard against which all others are measured. Throughout the world in industry and standards laboratories, the Morehouse Proving Ring is recognized for its lasting reputation of unquestionable accuracy in the measurement of mechanical forces. For this reason, it is accepted as a prominent standard for the calibration of testing machines, torque measuring dynamometers, thrust standards, electronic and hydraulic load cells, and much other force measuring devices and systems.
The calibration standard against which all others are measured is available in digital versions. Digital versions have proven to be more accurate, easier to use, and are the preferred option. Rings are often the choice for those wanting stability.
This page is kept up for reference only.
Morehouse Proving Rings are known for:
Stability - When maintained, Proving Rings have little to zero drift.
Longevity - Some Proving Rings built in the 1930s are still in use today.
Accuracy - Proving Rings often maintain uncertainties of 0.0125 - 0.025 % of full scale.
Reliability - There's a reason a Proving Ring is on the International Space Station. They do not fail.
Rings are available in two different models:
This is the most accurate proving ring available
ISO Class 00 @ 10 % of range ASTM E74 lower limit factor is better than 0.0125 % of full scale
There are roughly 20,000 counts of resolution
There are roughly 40,000 counts of resolution
Available in capacities from 2,000 lbf or equivalent up to 1,000,000 lbf or equivalent
This is model is best suited for calibrating tensile machines in accordance with ASTM E4 and ISO 7500
ASTM E74 lower limit factor is better than 0.0250 % of full scale; ISO Class 0.5 at 10 % of range
Available in capacities from 300 lbf or equivalent up to 1,000,000 lbf or equivalent
1742 Sixth Ave.
York, PA 17403