Frequently Asked Questions
Welcome to our Frequently Asked Questions (FAQs) page. Here you will find answers to questions most commonly asked by our customers on all aspects of weighing supply, service and support.
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What is USP Chapter 1251?
USP Chapter 1251 is titled ‘weighing on an analytical balance’ and unlike chapter 41 is only a recommendation. The scope of this procedure includes any balances used during an analytical procedure.
The chapter covers the performance of the balance taking into consideration its intended use and the balance location and therefore the environmental effects.
Northern Balances can offer a UKAS Calibration Certificate for your balance to demonstrate how your balance is performing, and can also offer ‘IQ OQ PQ’ (Installation Qualification, Operational Qualification and Performance Qualification) to establish that the type of equipment is correct for use and performing as it should. If you require further guidance on which service is most suitable for you, please speak to our metrology experts.
Calibration determines both measurement and equipment performance. With routine equipment calibration and adjustment, you can measure safely, ensure compliance and avoid the costs of inaccurate measurements.
The frequent calibration of your weighing equipment ensures that it gives consistent and reliable readings, in line with your quality certification and current legislation. The importance of calibration is not just to check that the instrument’s displayed values are within specification, but also to help you understand the inaccuracy of the displayed values at specific points of measurement. When you’re calibrating an instrument it is best practice to calibrate at points of measurement critical to the instrument’s application.
Northern Balance offers both UKAS and UKAS Traceable calibration, which determine the ongoing performance of your weighing equipment over time. With routine equipment calibration and adjustment by our engineers when required, you will measure safely, ensure quality compliance and avoid the significant and avoidable costs of taking inaccurate measurements.
Our experienced calibration engineers can help you to determine the calibration procedures and frequency which best suits your weighing requirements in order that you remain compliant.
Northern Balance offers a comprehensive range of service options which are tailored to suit every type of client from national group contracts to sole traders. We aim to give our clients the highest quality of service combined with exceptional value for money.
Our Service Engineers are trained to a very high standard and have a vast amount of product and industry knowledge. We are continuously looking to challenge and improve ourselves and work closely with various Accreditation bodies, equipment manufacturers and independent weighing experts.
The after sales service shouldn’t be taken for granted as it’s a hugely important factor. Effective and timely maintenance/calibration ensures that the quality of our customer’s products or their profit margins are kept intact. At Northern Balance, we believe in the concept of preventive maintenance rather than corrective actions.
What is Type Approval?
Weighing instruments that are used for legal or controlled applications are required to meet various legal requirements of the relevant EU directives and the associated UK Regulations.
Examples of legal and controlled applications: Medical weighing (e.g. where a person’s weight could affect a prescribed drug or a procedure), Selling anything based on its weight (e.g. shops or production sites that are sampling a product to be sold), Legal testing (e.g. Blood, alcohol or drug testing).
‘Under the NAWI and Measuring Instruments Directives, EC-Type examination certificates can only be issued by Notified Bodies who have been designated in their Member State for this task. The National Measurement Office (NMO) is the designated Notified Body in the UK for issuing EC TACs for both non-automatic and automatic weighing instruments. Member States of the EC are obliged to accept type-approval certificates issued by Notified Bodies of other Member States.’ [UK Weighing Federation]
The Type Approval confirms that the item or type of machine conforms to the relevant regulation. All equipment with a Type Approval will be classified as either class I, class II, Class III or class IV. The classification relates to the accuracy of the weighing instrument/s.
What is Verification?
An initial Verification / Legal Verification is performed when a weighing instrument is put into service. The Verification process tests the weighing capabilities of a weighing instrument. Test weights of a defined class are required based on the Type Approval class of the weighing equipment. The robust test methods used to ensure that the individual weighing instrument conforms with the legal requirements and with the Type Approval.
Initial Verification can be performed by a Trading Standards Officer, a Notified Body (National Measurement Office for the UK) or a self-verifier.
When the initial Verification is complete, the machine will be labelled with specific Verification labels (These include the CE mark, the year of the verification and the number of the notified body).
The scale will be marked with the scale division (d), but will also be marked with the verified division (e). These 2 divisions can be exactly the same, but in many scenarios, the verified division will be 10 times greater than the scale division. (eg. If d=0.1g then it is possible for e=1g).
Northern Balance can arrange a full initial verification for your equipment and can ensure all legal requirements are met.
What is Re-Verification?
When a machine has previously been verified and it isn’t performing as it should during a calibration check, or when the machine has had anything done to it that could jeopardise the calibration of the weighing instrument, a re-verification is required. As with an initial verification, the re-verification can be performed by a Trading Standards Officer, a Notified Body (National Measurement Office for the UK) or a self-verifier. Examples of when the accuracy of a verified weighing machine could have been jeopardised are by having the calibration seals broken for calibration adjustments, or when a display has been changed.
Northern Balance offers a full calibration service that will establish if your weighing instruments require re-verification. If they do, we can also perform the verification on site.
What is USP?
The United States Pharmacopeia (USP) is a not for profit organisation in the United States, who publish documentation and requirements for the standards required for medicines, food ingredients and dietary supplement products.
Prescriptions and over the counter medicine within the United States are required by law to comply with the USP-NF public standard.
What is USP Chapter 41?
USP chapter 41 was updated and put into action in December 2013. This chapter titled ‘Balances’ and the update in 2013 is focused on repeatability and accuracy.
Within the equations behind the repeatability tests performed as prescribed in chapter 41, the balances operating range is defined, and therefore the minimum weight that can be reproduced accurately. Furthermore is prescribes the classification and tolerance of the test weights used when testing the repeatability.
Northern Balances can perform the prescribed tests using our UKAS calibrated test weights, to ensure the operating range is defined, and the starting point for the operating ranged is certified and labelled on your weighing equipment.