Frequently Asked Questions
Q. What is the basic principle of operation of weighing equipment?
A. Weighing scales and balances measure weight by measuring the amount of force exerted on the load cell. They then convert the millivolt that results to mass and display it in various units of denominations.
Q. Can you convert weighing equipment?
A. Yes, on platform scales, we can change loadcells, indicators and modify solid structures. On weighbridges, we can change to different loadcells and indicators only if everything is compliant with the NRCS. In such an instance, it will therefore be necessary to get approval granted first.
Q. Is it possible to build weighing systems to suite the client’s business requirements?
A. Yes, we can convert hoppers to weigh products and convert batch plants for weighing materials and liquids, for example, fertiliser plants, cement plants and or chemical plants etc.
Q. What are the components required in a weighing process?
• Base or Platform
• An Indicator / Instrument
• Junction Box
• Load Cells
Q. What are the latest communication protocols?
A. RS232, RS485, RS422, 4-20MA, Profibus, Modbus, Ethernet
Q. What do the scales add to a company’s quality features?
A. Protects consumers against short measures and ensures fair trade.
Q. What are the most significant differences between different kinds of scales?
• Nominal Scale
• Ordinal Scale
• Interval Scale
• Ratio Scale
Q. What are the different types of loadcells used for scales?
• Strain Gauge Load Cells
• Hydraulic Load Cells
• Pneumatic Load Cells
• Capacitive Load Cells
• Piezoelectric Transducers
Q. What are the different types of controllers used for scales?
A. Profibus type- No display unless you plug in a laptop
Remote display converted type – (scrap yards as people are locked in cash offices)
Common – display is on the indicator itself
Q. What are the pros and cons of old vs new generation scales?
A. New Scale Pro’s:
• Easier to maintain
• Parts are cheaper
• Used for multiple applications
New scales Con’s:
• Life span shorter
• Less durable
• Gets affected by load shedding and lightning, and power surges
Older scales Pro’s:
- Lifespan is up to triple
- Extremely durable
- Doesn’t get affected due to poor power or lightning
Older scales Con’s:
- Breakdown time can be weeks due to engineering new parts
- Repair time is triple due to the dismantlement and reassembly
- Not as accurate as a digital scale.
The table below explains the difference between verification and calibration
|South African National Standard-SAN10378: General requirements for competence of verification laboratories in terms of the legal Metrology Act||International Standard-ISO17025: General requirements for the competence of testing and calibration laboratories|
|Accredited to verify specific instruments used for trade purposes.
Instruments need to have gone through the Type Approval process as carried out by the Legal Metrology Department (NRCS)
|Accredited to calibrate instruments used in industry within the laboratory’s scope|
|Verify: means to certify the accuracy of any measuring instrument based on any relevant measuring standard||Calibration: A set of operations that establish the relationship between values of quantities indicated by a measuring instrument, and the corresponding values realised by standards|
|Not accredited to transfer traceability||Involves transfer of traceability using actual values of standards as opposed to nominal values|
|Verification certificates must state, inter alia, compliance with the requirements of the Legal Metrology Act and Regulations||Calibration certificates to state, inter alia, the calculated Measurement Uncertainty in accordance with ISO GUM, and evidence that the measurements are traceable|
|A verification certificate cannot be issued as a calibration certificate claiming compliance with the requirements of ISO 17025||A calibration certificate cannot be issued as a verification certificate allowing/disallowing an instrument to be used for trade|
|Verification intervals for instruments used in trade are prescribed in the Legal Metrology Act||Calibration certificates shall not contain any recommendation on calibration interval unless agreed with the client|