Laboratory Balances & Scales, Lab Weighing METTLER TOLEDO

    Laboratory Weighing

    Balances and Scales for the Laboratory

     

    Laboratory Weighing – Laboratory Balances and Scales

    What is the difference between mass and weight?

    The words ‘mass’ and ‘weight’ are frequently used interchangeably, and both are determined by weighing, however, in terms of laboratory balances and scales, the difference between the two is key. Mass measures the amount of material in any given item, is independent of location, and remains the same, no matter their environment.

    Mass is measured via comparison using a laboratory scale and balance. The kilogram is the SI unit of mass; it is equal to the ‘International Prototype Kilogram’ (IPK), the original object from which the measurement derived.

    An object’s weight is how hard gravity is pulling on the mass, as a force. The SI unit for weight is the Newton (= 1 kg x m/s2). An object with a mass of 1.0 kg weighs approximately 9.81 Newtons on the surface of the earth (mass multiplied by earth’s gravity). The weight of an object on a mountain will be less than at sea level, due to gravitational variations - a high accuracy balance or laboratory scale will detect such differences.

    The redefinition of the kilogram is scheduled for 2018. Supporting Redefinition of the Kilogram offers further reading about the change.

    Although mass and weight are different entities, the process of determining both weight and mass is called weighing.

     

    How do electronic balances work? What is the electromagnetic force compensation principle?

    With mechanical balances, a sample is placed on one end of the beam, reference weights on the other, until it is perfectly balanced, the sum value of the weights representing the mass of the sample.

    Electronic precision balances, analytical balances, and microbalances in high accuracy classes work with a sensor based on electromagnetic force compensation. A coil on a free movable beam is inserted in a permanent magnetic field. An optical electronic sensor current maintains its position, controlled to an accuracy greater than one thousandth of a millimetre. The sensor records vertical position changes when the pan is loaded which is used to change the current in the coil to return to its initial position. The more weight is added to the pan, the more current is needed to compensate it, this is digitized on the display.

     

    Laboratory balances and readabilities

    Common laboratory balances and scales types are ultra-micro, micro, semi-micro, analytical, and precision balances.

    The readability of a balance is the smallest difference between two measured values that can be read on the display. With a digital display this is the smallest numerical increment, also called the scale interval. The readability of a balance is not equivalent to its weighing accuracy.

    Several properties may limit performance. The most important are repeatability (RP), eccentricity (EC), nonlinearity (NL) and sensitivity (SE).

    Our Laboratory Balances and Scales video course Basics and Weighing Influences explains basic concepts of good weighing practice.

     

    How to select the right laboratory balance or laboratory scale?

    For accurate measuring, consider:

    • Required weighing accuracy -> sets the upper limit to the allowable measurement uncertainty of the balance to ensure process tolerances e.g. 1%
    • Safety Factor -> ensures that even with changes over time, the required weighing accuracy is still kept
    • Required smallest net weight to be weighed -> specifies the minimum weight the laboratory scale must achieve (according to measurement uncertainty and/or customer process tolerances)
    • Largest weight to be weighed (including tare) -> specifies the capacity of the lab scale
    • Environmental conditions and weighing application -> specifies further properties of the laboratory balances and scales

    Make sure that you select a lab balance or laboratory scale that meets YOUR process requirements and respective tolerances.

    Good Weighing Practice™ (GWP®) is a universal approach to selecting and testing weighing instruments. A global standard, it can be used in any industrial and working area for new or existing weighing systems. GWP® provides documented evidence for reproducible weighing results in accordance with all current quality standards.

    Offering reliable product quality and regulatory compliance, GWP® is a benchmark for laboratory balances and scales, and uses two key issues to determine quality:

    • The weighing capacity must be larger than the largest gross load expected to be weighed by the user
    • The minimum weight of the weighing instrument for the accuracy required - including the safety factor - must be smaller than the smallest sample expected to be weighed by the user.

     

    What is the resolution of a laboratory weighing instrument?

    The resolution is the degree to which change can be detected, usually expressed as a number of points. It is the capacity (in g) divided by the readability (in g).

    An analytical balance or scale with a capacity of 200 g and a readability of 0.00001 g has a resolution of 20 million points. METTLER TOLEDO’s highest resolution comparator is the M1 mass comparator, with 1 billion points.

     

    Which tolerances are applicable in weighing processes?

    Tolerances determine whether a lab balance or lab scale behaves "well enough" to meet process requirements and how much deviation is permittable. Tolerances set the criteria to issue a Pass/Fail statement. Tolerances come from a variety of sources, including legal agencies, manufacturing industries, and the process itself.

    • Legal tolerances:
      Legal tolerances stipulated by OIML R76 or NIST Handbook 44 (US only) assess legal for trade requirements. These tolerances are quite large and easily met with laboratory balances, or when weighing at the lower end of the measurement range.
    • Manufacturer tolerances:
      Manufacturer tolerances ensure that equipment meets manufacturer specifications. Manufacturer tolerances do not consider user specific process requirements, and are unsuitable for improving the weighing process.
    • Process tolerances:
      Specific process tolerances defined by the user, support process improvements and savings on material, waste and rework. For laboratory scales in a legal for trade application, process tolerances should be applied in addition to legal tolerances. For more details on METTLER TOLEDO's GWP Verification® visit: Good Weighing Practice.

      Legal tolerances protect consumers but do not consider specific producer requirements. Optimising process tolerances can have a large impact on process profitability.
     
    Analytical balances

    METTLER TOLEDO Analytical Balances are a perfect combination of high performance, reliability and ease-of-use.

    Mettler-Toledo Precision Balances

    METTLER TOLEDO Precision Balances are made for reliable and high-precision weighing. Both in the lab and under harsh industrial conditions.

    Microbalance and Ultra Micro Balances

    Exceeding the limits of weighing: Excellence Microbalance and Ultra Micro Balances display unsurpassed accuracy even with the smallest of samples.

    Automated Powder and Liquid Dosing

    Automated dispensing of 1 mg to 5 g of free-flowing powders with liquid dispense option to make dosing easier and safer.

    Good Weighing Practice™ (GWP®)

    GWP® is a global weighing standard that can be applied to new or existing weighing equipment from any manufacturer in any industry and workplace.

    Moisture Analyzer

    The METTLER TOLEDO family of moisture analyzers provides fast, precise and reliable moisture determination.

    Special & Segment Solutions for weighing

    Gold and Carat Balances, Stent- and Filter Weighing Solutions, Calibration Solutions for Micro-, Single- and Multichannel Pipettes - we offer a broad portfolio tailored to your special needs.

    Mass Comparators

    Mass Comparators set the standard in mass metrology and ensure traceability to the international prototype.

    Test Weights for Scales

    Select weights to test your balance with a wide range from 50 µg to 5000 kg, and optimize your calibration processes with smart accessories.

    Applications

    Applications for Weighing in the Laboratory

    Publications

    Services

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    Call Service

    Software & Accessories

    Software

    MC Link Mass Calibration Software
    LabX direct Software
    Calibry Pipette Calibration Software
    Application Software

    MC Link Weight Calibration Software

    LabX direct Software

    Calibry Pipette Calibration Software

    Application Software

    METTLER TOLEDO offers for their comparators a variety of software solutions. No matter if security, proficiency or dissemination is the challenge, we conquer all.
    Transfer the results from your balance or moisture analyzer directly into Excel.
    Calibry supports all steps of the pipette calibration process, saves all data, and facilitates compliance with ISO 8655 and 21 CFR Part 11.
    Solutions are available for a range of weighing applications e.g. batching, SQC etc.
    MC Link Mass Calibration Software

    METTLER TOLEDO offers for their comparators a variety of software solutions. No matter if security, proficiency or dissemination is the challenge, we conquer all.

    LabX direct Software

    Transfer the results from your balance or moisture analyzer directly into Excel.

    Calibry Pipette Calibration Software

    Calibry supports all steps of the pipette calibration process, saves all data, and facilitates compliance with ISO 8655 and 21 CFR Part 11.

    Application Software

    Solutions are available for a range of weighing applications e.g. batching, SQC etc.

    Accessories

    Label printing Scale and Laboratory Scale printers
    ErgoClips
    MinWeigh Doors
    AntiStatic Kits

    Thermal and Dot Matrix Printers

    ErgoClips

    MinWeigh Doors

    AntiStatic Kits

    Connect your balance or lab instrument to a printer to document results and to ensure compliance with GMP/GLP/ISO.
    ErgoClip container holders allow precise and secure positioning of tare vessels on the balance. Dose straight into the tare vessel in one easy step.
    Dosing through this small adjustable opening in the draft shield minimizes air turbulence in the weighing chamber to give fast, stable results.
    Safely remove electrostatic charge from your sample and tare container before weighing. Automatic options available.
    Evaporation Traps
    Weighing Tables
    Optional Interfaces
    Connection Cables.

    Evaporation Traps

    Weighing Tables

    Optional Interfaces

    Connection Cables.

    Mount the Evaporation Trap on your balance to get the perfect pipette testing setup and minimize errors caused by evaporation.
    Height adjustable Weighing Tables provide a stable weighing surface and an ergonomic working area for every type of balance.
    Optional interfaces for Ethernet, Bluetooth, PS / 2, RS232 and LocalCAN allow easy connection to other instruments, peripherals, PCs and networks.
    Connection to other instruments, peripherals, PCs and networks is easy with the correct connection/interface cable.
    Optical sensors and switches
    Auxiliary Displays and Stands
    Anti-Theft Devices
    Barcode Scanners

    Optical sensors and switches

    Auxiliary Displays and Stands

    Anti-Theft Devices

    Barcode Scanners

    Sensors, foot switches and adapters allow convenient hands-free operation.
    Extra displays as well as stands for terminals and printers allow you to create a truly ergonomic workspace.
    Lock your balance with an anti-theft device.
    Save time and avoid transcription error by automatically reading-in sample, container and user IDs.
    Density Determination
    Draft Shields
    External Power Units
    Below Balance Weighing Devices

    Density Determination

    Draft Shields

    External Power Units

    Below Balance Weighing Devices

    Built-in density determination software guides you step-by-step through the density determination of solid, liquid or pasty substances.
    A range of draft shields are available to protect your samples from environmental influences.
    Power adapters and cords for 115V and 220V.
    Below balance weighing devices for SB/SR/SG models.
    Consumables/Accessories for Moisture Analyzers
    Protective Covers & Transport Cases
    Accessories for Weighing Modules
    Pans & Weighing Pans

    Consumables/Accessories for Moisture Analyzers

    Protective Covers & Transport Cases

    Accessories for Weighing Modules

    Pans & Weighing Pans

    Useful accessories for accurate moisture determination e.g. absorbent glass-fiber filters, aluminum sample pans.
    Shield your balance from dust and accidental soiling with a protective cover. Transport cases protect your balance from damage during relocation.
    The METTLER TOLEDO accessories for weighing modules make connection considerably easier and make it possible to construct a network of several weighing platforms.
    Optional weighing pans for a range of different applications.
    Filter Weighing Accessories
    Weight Accessories
    Magnetic Protection Shield (MPS)
    Literature

    Filter Weighing Accessories

    Weight Accessories

    Magnetic Protection Shield (MPS)

    Literature

    A Filter Weighing Kit on an Excellence Balance provides a state-of-the-art solution for determining particulate matter on filters down to 0.1 μg.
    This comprehensive range of accessories for professional weight handling includes tweezers, weight forks, weight grips and leather gloves.
    The MPS weighing pan protects against magnetic forces and allows magnetic stir bars to be used without affecting the weighing results.
    Our Weighing Dictionary is an illustrative guide for daily use explaining more than 1000 terms associated with weighing technology and related areas.
    SmartPrep

    SmartPrep

    The disposable weighing funnel SmartPrep is an innovative single use consumable to simply and securely weigh-in powders prior to volumetric sample preparation.
    Label printing Scale and Laboratory Scale printers

    Connect your balance or lab instrument to a printer to document results and to ensure compliance with GMP/GLP/ISO.

    ErgoClips

    ErgoClip container holders allow precise and secure positioning of tare vessels on the balance. Dose straight into the tare vessel in one easy step.

    MinWeigh Doors

    Dosing through this small adjustable opening in the draft shield minimizes air turbulence in the weighing chamber to give fast, stable results.

    AntiStatic Kits

    Safely remove electrostatic charge from your sample and tare container before weighing. Automatic options available.

    Evaporation Traps

    Mount the Evaporation Trap on your balance to get the perfect pipette testing setup and minimize errors caused by evaporation.

    Weighing Tables

    Height adjustable Weighing Tables provide a stable weighing surface and an ergonomic working area for every type of balance.

    Optional Interfaces

    Optional interfaces for Ethernet, Bluetooth, PS / 2, RS232 and LocalCAN allow easy connection to other instruments, peripherals, PCs and networks.

    Connection Cables.

    Connection to other instruments, peripherals, PCs and networks is easy with the correct connection/interface cable.

    Optical sensors and switches

    Sensors, foot switches and adapters allow convenient hands-free operation.

    Auxiliary Displays and Stands

    Extra displays as well as stands for terminals and printers allow you to create a truly ergonomic workspace.

    Anti-Theft Devices

    Lock your balance with an anti-theft device.

    Barcode Scanners

    Save time and avoid transcription error by automatically reading-in sample, container and user IDs.

    Density Determination

    Built-in density determination software guides you step-by-step through the density determination of solid, liquid or pasty substances.

    Draft Shields

    A range of draft shields are available to protect your samples from environmental influences.

    External Power Units

    Power adapters and cords for 115V and 220V.

    Below Balance Weighing Devices

    Below balance weighing devices for SB/SR/SG models.

    Consumables/Accessories for Moisture Analyzers

    Useful accessories for accurate moisture determination e.g. absorbent glass-fiber filters, aluminum sample pans.

    Protective Covers & Transport Cases

    Shield your balance from dust and accidental soiling with a protective cover. Transport cases protect your balance from damage during relocation.

    Accessories for Weighing Modules

    The METTLER TOLEDO accessories for weighing modules make connection considerably easier and make it possible to construct a network of several weighing platforms.

    Pans & Weighing Pans

    Optional weighing pans for a range of different applications.

    Filter Weighing Accessories

    A Filter Weighing Kit on an Excellence Balance provides a state-of-the-art solution for determining particulate matter on filters down to 0.1 μg.

    Weight Accessories

    This comprehensive range of accessories for professional weight handling includes tweezers, weight forks, weight grips and leather gloves.

    Magnetic Protection Shield (MPS)

    The MPS weighing pan protects against magnetic forces and allows magnetic stir bars to be used without affecting the weighing results.

    Literature

    Our Weighing Dictionary is an illustrative guide for daily use explaining more than 1000 terms associated with weighing technology and related areas.

    SmartPrep

    The disposable weighing funnel SmartPrep is an innovative single use consumable to simply and securely weigh-in powders prior to volumetric sample preparation.

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