As per the Legal Metrology Act, 2009, verification refers to the process of inspecting, testing, and stamping weights, measures, and measuring instruments to ensure they comply with legal standards and accuracy requirements. This is done to prevent fraud and ensure fair trade practices. All weights and measures used in commercial transactions must be verified and stamped by the legal metrology department. Verification must be conducted at regular intervals as prescribed by the state government. Once verified, an official seal or stamp is affixed to the instrument as proof of compliance. The verification process is carried out by designated officers, such as Inspectors of Legal Metrology. Using unverified or inaccurate weights and measures can result in fines or legal action. Additionally, the Kerala Legal Metrology (Enforcement) Rules, 2012 provide state-specific guidelines and can be accessed through the Kerala Legal Metrology Department’s official portal. These rules are essential for businesses and individuals involved in manufacturing, selling, or using weights and measures, ensuring compliance and promoting consumer trust in trade practices.

One of the following Standards shall be used for every weighing and measuring process.
1. Weights
2. Measures.
3. Weighing Instruments.
4. Measuring Instruments.

These devices used for commercial purpose and industry is generally belongs to the category of weights and Measures for Commercial/Industrial Use. The accuracy of these weights and Measures are maintained in verification process as per the following hierarchy of traceability.

Hierarchy of Traceability in Legal Metrology:

1. InternationalStandards
o MaintainedbyorganizationslikeBureauInternationaldesPoidsetMesures(BIPM).
o Theseserveastheprimaryreferenceforallmeasurementsystemsworldwide.
2. NationalStandards
o MaintainedbyNationalMetrologyInstitutes(NMIs)suchasNationalPhysical Laboratory (NPL) in India.
o Thesearederivedfrominternationalstandardsandactasthehighestauthorityin a country.
3. ReferenceStandards
o Maintainedbydesignatedlaboratoriesaccreditedbynationalbodies.
o Usedforcalibratingsecondarystandards.
4. SecondaryStandards
o Verifiedandmaintainedby StateLegalMetrologyDepartments.
o Usedforverifying working standards.
5. Working Standards
o UsedbyLegalMetrologyOfficersfortestingandverifyingcommercialweights and measures.
6. Commercial/IndustrialUse
o Includesweighingmachines,fueldispensers,andtradeinstrumentsusedby businesses.
o Thesemustbecalibratedperiodicallytoensurecompliancewithlegalmetrology regulation.

ScopeofVerificationProcess.

✔Ensuresuniformityinmeasurementsacrossindustries.
✔Reducesmeasurement errorsandfraud.
✔Maintainsconsumerprotectionandfair trade.
✔Helpsinlegalenforcementanddispute resolution.

Standard Weights for Commercial and Industrial Use

Iron Weights Parallelopiped Hexagonal (50 kg to 5 kg)	Cylindrical Knob Type Weights (10 kg to 1 g)	Iron Weights (50 kg to 50 g)

 

Bullion Weights (10 kg to 1 g)	Sheet Metal Weights (500 mg to 1 mg)	Carat Weights (500 carat to 0.005 carat)

These weights are tested using check weights with accuracy equivalent to working standard weights and Working standard balances. The tolerance of these weights is specified in fifth schedule of The Legal Metrology General Rules 2011.The Legal Metrology Officer Issue a Certificate of Verification after stamping if the accuracy is verified with in the Maximum Permissible Error and Certificate of rejection with reasons in case beyond the Maximum Permissible Error. After carrying out necessary repair the rejected weight or measure maybe produced before the Legal Metrology Officer for re- verification within the period of seven days or within the extended period, as the case may be, failing which the weight or measure shall be abandoned. Fees payable for verification and stamping of weigh tor measure at the office or camp office of the Legal Metrology Officer shall be as specified in Schedule X of The Kerala Legal Metrology Enforcement Rules 2012.’

 

Measures

The following types of Measures are commonly used as Measure, which includes Capacity measures and Length measures as follows.

1. Liquid Capacity Measures

Dipping: 20 ml to 1 L Pouring: 20 ml to 2 L	Conical measure (100 ml to 20L)

2. Dispensing Measures

Beaker measure (500 ml and 1000 ml)	Conical measure (5 ml to 200 ml)

3. Liquor Measure.(Hand Operating and Automatic)

Hand Operating: (30 ml, 60 ml and 100 ml)	Hand Operating (30 ml, 60 ml and 100 ml)	Hand Operating: 30 ml, 60 ml and 100 ml

4. Length Measure Non-Flexible Scales. (Wooden and Metallic)

Wooden:0.5m,1 m, 2m	Metallic:0.5 m and 1 m

5. Folding

Denomination:0.5 m and 1 m

 

6.Fabricor Plastic Tape Measure.

 

7. Steel Tapes Measures.

 

8. Surveying Chains

9.Tapes for Use in the Measurement of Oil Quantities.

Nominal length 5 m, 10 m,15 m, 20 m, 25 m and 50 m

When produced for verification after payment of the prescribed Fee, The Legal Metrology Officer Issue a Certificate of Verification after stamping if the accuracy is verified with in the Maximum Permissible Error and Certificate of rejection with reasons in case beyond the Maximum Permissible Error.

Weighing Instruments.

These are the kind of Instruments specified in The Seventh Schedule of the Legal Metrology General Rules 2011.
1. Non-Automatic Weighing Instruments.
2. Beam Scales and Counter Machines.
3. Automatic Rail Weigh Bridge.
4. Automatic Gravimetric Filling Instruments.
5. Discontinuous Totalizing Automatic Weighing Instruments (Totalizing Hopper Weighers).

The commonly used Platform type mechanical and Digital Balances in the hill-produce merchant shops, electronic weighing Machines in Grocery shops and markets, Precision balances in Laboratory and jewelry, Weigh Bridges for weighment of vehicle Loads etc. falls in the category of non-automatic Weighing Instruments.

 

		Electronic Weighing Machine
Precision Balance	Mechanical Platform Balance	Digital Platform Balance

Weigh Bridge Verification kit of The Lega lMetrology Department.

The image shows a Weighbridge Verification Kit used by the Legal Metrology Department to verify the accuracy of weighbridges used for weighing trucks. This specialized vehicle is equipped with standard calibrated weights and precision measurement tools to conduct tests and ensure compliance with regulatory standards.

Purpose and Function:

1. Accuracy Testing: Ensures weighbridges provide correct readings to prevent fraud and errors in trade.
2. Regulatory Compliance: Verifies that weighbridges meet legal requirements and standards.
3. Periodic Calibration: Conducts regular inspections to maintain measurement reliability.
4. Prevention of Overloading: Helps monitor truck weights to enhance road safety and reduce infrastructure damage.

The verification of Non-Automatic Weighing Instruments (NAWIs) under the Legal Metrology (General) Rules, 2011 involves several tests to ensure accuracy, reliability, and compliance with prescribed standards. The Legal Metrology officer performs relevant tests during verification which Includes the following.

1. Visual Inspection

• Checking the markings and inscriptions (manufacturer details, capacity, class, serial number, etc.).
• Ensuring physical integrity, proper assembly, and no unauthorized modifications.
• Verification of sealing provisions to prevent tampering.

2. Metrological Tests

These tests confirm the instrument’s accuracy and performance under normal operating conditions.
a. Repeatability Test
• Multiple weighing of the same load are performed to check if the instrument provides consistent results.
• The difference between the highest and lowest readings should be within acceptable limits.
b. Linearity and Accuracy Test
• The instrument is tested at different points across its measuring range.
• It must not deviate beyond the permissible error limits.
c. Eccentric Loading (Off-Center Load) Test
• Weights are placed at different positions on the weighing pan (corners and center).
• The variation in readings must remain within acceptable error margins.
d. Sensitivity Test
• Checks if the instrument can detect small weight variations.
• A minimal load change should cause a detectable change in the reading.
Apart from the above kind of tests performed for reverification, some additional tests as prescribed by the Legal Metrology General Rule 2011 as given below are performed to decide whether the metrological requirements meet up for the purpose of model approval of weighing instruments.
1. Influence Factor Tests
These tests ensure the weighing instrument maintains accuracy under different environmental conditions.
a. Temperature Variation Test
• The instrument is tested at different temperatures to check for drift in readings.
b. Voltage Fluctuation Test (for electronic NAWIs)
• The weighing instrument is tested under varying power supply conditions to assess performance stability.
c. Vibrations and Mechanical Stability Test
• Simulates real-world conditions to ensure the scale remains stable under external disturbances.
2. Hysteresis Test
• The weight is increased and then decreased to observe if there is any difference in readings due to mechanical or electronic lag.
3. Weighing Range and Overload Test
• The instrument is tested at its maximum and minimum capacity.
• It should not exhibit permanent deformation or inaccurate results when exposed to its rated capacity.
4. Time Stability (Creep) Test
• A constant load is placed for a prolonged period to check for any gradual change in readings.
If the instrument passes the test, an official verification stamp or seal is applied. This certifies compliance with legal metrology standards. If the test results show results beyond Maximum Permissible Error, the Legal Metrology Officer Reject the instrument with a certificate to that effect.

Measuring Instruments

The Eighth Schedule of the Legal Metrology (General) Rules, 2011, titled “Specifications for Measuring Instruments”,provides detailed specifications for various measuring instruments to ensure their accuracy and reliability. This schedule is divided into several parts, each focusing on a specific type of measuring instrument namely,

1. Volumetric Container Filling Machines: Guidelines for machinesdesignedtofillcontainerswith liquids, ensuring precise volume measurements.
2. BulkMeters:Specificationsformetersusedtomeasurelargevolumesofliquids,commonlyused in industries like fuel distribution.
3. Water Meters: Standards for devices measuring water consumption, ensuring accuracy for both residential and commercial use.
4. MeasuringSystemsforLiquidsOtherthanWater: Criteriaforsystemsmeasuringliquidssuchas oils, chemicals, and beverages, excluding water.
5. Volumetric Container Type Liquid Measuring Devices: Specifications for devices that measure liquid volume by filling a known container size.
6. ClinicalThermometers: Standards ensuringthe accuracy andreliability ofthermometers usedin medical settings.
7. ManometersorInstrumentsforMeasuringArterialBloodPressure(Sphygmomanometers):
Guidelinesforbloodpressuremeasuringdevices,ensuringtheyprovideaccuratereadings.
8. Taximeters: Specificationsfor devices installed incommercial passenger vehiclesto calculate fares based on distance traveled and waiting time.
9. Speed Governors:Specifications for devices installed to regulate and limit maximum speed, ensuring compliance with legal speed limits and enhancing road safety. These devices prevent over speeding, reduce accident risks, and improve fuel efficiency.
10.Compressed Gaseous Fuel (CNG) Measuring Systems for Vehicles: Standards for systems measuring the amount of compressed naturalgas dispensed to vehicles, ensuring accurate billing.

Dispensing Pump Units in Fuel Stations

Dispensing pump units, commonly using at fuel stations, are systems used for measuring and delivering liquid fuels like petrol, diesel, Diesel Exhaust Fluid belongs to the category of Measuring Systems for Liquids Other than Water. These units are subject to strict regulations under Legal Metrology (General) Rules, 2011 (Eighth Schedule) to ensure accurate measurement and prevent fraud.

Calibration of dispensing pump units is a crucial process to ensure the accuracy and reliability of fuel measurements at fuel stations. It is conducted by the Legal Metrology Department in accordance with the Legal Metrology (General) Rules, 2011.

Vehicle Tank Calibration Unit

A Vehicle Tank Calibration Unit is a specialized system used to verify and calibrate the fuel tanks of vehicles, such as fuel tankers, transport trucks, and storage tanks. The calibration ensures that the volume measurements of the tank are accurate and comply with legal metrology standards. Nineth schedule of Legal Metrology (General) Rules, 2011 prescribes the Procedure for calibration of Vehicle tanks. Currently the Kerala Legal Metrology Department operates this Facility at Ernakulam,Kozhikode, Pathanamthitta and Kollam District and the unit in Kasaragod district is under Construction.

Crane Weigh Bridge

Crane weighbridges, also known as crane scales or overhead weighing systems, are specialized devices designed to measure the weight of loads lifted by cranes. They are essential in various industries, including manufacturing, shipping, and construction, where precise weight measurements are crucial for safety and operational efficiency.In Kerala, the Legal Metrology Department regulates the use of weighing instruments, including crane weighbridges, to ensure accuracy and compliance with legal standards. All weighing devices must be verified and stamped by the department to certify their precision and adherence to regulations. Regular inspections and calibrations are mandated to maintain measurement accuracy.