Calibrating Mechanical Measurement Quantities

esz AG's laboratories for pressure, balancing scales/ weight (mass), force, virbation, shock and accelaration are designed to provide additional calibration opportunities for industrial test and measurment equipment.

What size, what height, how strong, how fast? esz knows the answer, precisely.

Based upon the definition of mass, the so called SI-unit kilogram, calibration for test objects, standards and primary calibration systems is processed by utilizing measurement scales for all relevant mechanical measurement quantities such as mass, force, torque, acceleration, mass flow or accoustic pressure and provided to customers most accurately. Besides all of the above esz AG provide answers and discuss all questions regarding common measurement technology, evaluate measuring results and procedures, constantly and are actively taking part in national measurement committees.

Calibrating Force

Whether in vibration technology or mechanical engineering: Measuring force or torque is key to multiple applications in industry and R&D, such as for instance material testing. Calibration is performed by acquiring measurement data automatically, applying quasi-static (pull and stress) loads to force meters, force sensors or load cells.

Accuracy down to 5 parts of a million at 5 metric tons

Extremly precise measurements (at 0,05 % reading and better) are realized considering an extraordinary high inclination (50 N to 50 kN). The calibration standard's characteristics for force and corresponding quantities correlate with direct mass comparators under weight in the earth's gravitiy field. All measurement procedures are performed in compliance with DIN EN ISO 376.

With respect to the latter two different approaches are identified:

• Including a reversing span element for calibration of (dual) force meters dedicated to measure and evaluate increasing and decreasing force.
• Excluding a reversing span element for calibration of force meters dedicated to measure and evaluate increasing force, only.

A reversing span element is required In order to determine the hysteresis. Electric signals are realized amplifiying reference calibration standards at measurement uncertainties of 60 nV/V.

Calibrating Torque

Torque is defined as power/ force times distance to the center of rotation. The measurement unit torque is derived form the unit power (Newton) and length (Meter). Newton is based upon the standard SI-unit kilogram, meter and second. Transduction and traceability in terms of calibration e.g. torque meters are subject to and in compliance with norms and regulations such as DIN EN ISO 6789, DIN 51309 or DKD-R 3-8. esz AG's toque calibration system is designated to calibrate electronic torque meters specified at 1 %.

Central Torque Initiation

Handling in terms of fitting position and direction are in accordance to ISO 6789. Initiation is performed centrally at the output and stabilized at the handle with respect to ISO requirements.

In addition, calibrating measuring chains consisting of sensor and display are technically feasible. For this a mechanical holding fixture is mounted centrally on top of the drive unit. To apply the load, the system supports sensors with 1/4", 3/8", 1/2", 3/4", 1". The power train can be equipped with a custom gearbox in order to tie the test object directly to the corresponding calibration standard. Air bearings will prevent the power train from transvers force and pertubation.

Calibrating Acceleration

Calibration for acceleration sensors and acceleration meters, probes and fixtures are utilized deploying a middle frequency acceleration calibartion system. The latter enables calibration at frequencies of 10 kHz and extremely low measurement uncertainties.

Through the lab at 30 multiple of g

According to ISO 16063-21 requirements esz AG is capable of calibrating acceleration up to 250 g and 300 m/s². Key to the calibration system is an oscillator with two back-to-back calibration standards enabling esz AG to perform secondary calibration of piezo-resistant and non-piezo-resistant class 1 sensors complying with ISO 16063. The high-precision calibration system is dedicated to field instruments and particular requirements in terms of accuracy and reliability. Calibration capabilities include high precision meters, sensors probes and fixtures for: electric charge/ load, voltage, ICP®, capacity, piezo-resitstant acceleration, acceleration and vibration.

Calibrating Mass, Balancing Scales and Weight

Calibrated test & measurement equipment require calibrated instruments. For instance in scales calibration, calibrated weights, so called mass pieces or standards are a pre-requirement. A scale will display correct values if properly and periodically maintained. Maintenance include thourough calibration and frequent adjustment. Documented calibration is determined to turn a scale into a reliable source for test results. Requirements are in accordance to calibration guideline EURAMET cg18 Rev, 4. The main objective is to determine measurement uncertainties in order to assess the quality in terms of test equipment accuracy and test results.

Great challenge at little amount of substance

The industrie's most vivid example for the importance of the exact amount is the medical field. Another explicit example is semi conductors. Exact doping in micrograms will determine material properties. Calibration is performed best at the stationary laboratory or on-site refering to first class calibration standards complying with DKD and OIML standards and procedures. Calibration is to be performed under draft-free conditions. Even tiny barometric variations will severly impact on measurement results.

Pressure Calibration

Pressure is defined as a means of resistance resulting from decreasing space available to matter. Pressure is an intense, scalar unit reflected in the SI-unit Pascal. The common unit symbol p is derived from the word pressure. The latter (in most cases) is equal to the quotient of Force F and Area A. Pressure calibration systems are based upon this principle. A well defined pressure (fluids or mass) is generated by applying defined force to a piston of known cross-sectional area. In practice this is realized applying loads to a vertical piston (piston manometer).

Extreme Accuracy Requirements

In addition precise measurments consider the fact that weight is dependent on gravitiy acceleration and tied to location. Extreme accuracy requirements refer to piston and cylinder deformation under pressure along with the loads uplift in air. To prevent measuring error derived from static friction an axle rotation is performed on the piston icluding the applied load. Nitrogen pressure controllers work at the same level of accuracy and enable measurement uncertainties of 60 ppm. However, the most common medium is hydraulic oil resulting in a working range from vacuum to 700 bar.

Mass Flow Calibration

esz AG's LaminarMasterFlow®-System (LFE) is designed for calibration in terms of air volume and mass flow test & measurement equipment. The system is operated under nearly atmospheric pressure and laid out to serve as a multiple, manual switching measurement ranges. The switching from and to a measuring range is carried out by physically disconnecting sensors from one measuring track and precisely reconnecting to the other measuring range including manual LFE adaptation. All four LFE ranges are mounted to a shared base. Core to the LFE is a digital ssystem including USB data acqusition hardware for analog conversion and data output. The sensor feed is built into a 19" chassis separated from the measuring track and the sensor system. In addition volume meters (BIOS DryCal ML-800-xx) including convertible mass flow measuring cells are utilized to increase the dynamic range to 1:100. Volumeter are equipped with almost friction less pistons including photo-optic sensor technology to instantly generate and display the flow. Atmospheric pressure correction and user defined temperature correction are integrated as part of the calibration system.

Calibrating Mass Flow at Minimal Measurement Uncertainties

Adjustment is realized by build in precision sensors in order to standardize the flow rate at for instance standard conditions (0 °C, 1013,25 mbar absolute reading). The latter performance feature is ideally combined with mass flow meters to provide users with number of measurent cycles to calculate the arithmetic mean. in Particular medicial and pharma industries rely on mass flow caibration at minimal measurement uncertainties, high precision and accuracy. esz AG's mass flow calibration system is DAkkS accredited since 2012.

The field mechanical calibration is specialized in calibration of test & measurement equipment as follows:

Scales and weight / pressure test equipment / canvas tension / acceleration test equipment / force test equipment / torque test equipment / mass flow equipment / flow meters