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The Verified Conformity Assessment Program, or VCAP, is a program proposed by the National Conference on Weights and Measures to ensure compliance of certain device types with environmental requirements. These device types are ones for which performance can be affected by changes in their physical environment. The intent of the VCAP is to provide a level of assurance that these devices perform at a level equal to or better than the device that was evaluated by NTEP.

Any device listed on a NTEP Certificate of Conformance whose performance can be affected by changes in its operating environment. Generally, these include load cells, digital weight indicators, weighing and load-receiving elements using load cells that do not have a NTEP certificate, complete scales, automatic weighing systems, belt-conveyor scales and automatic bulk weighing systems. The program will begin with load cells only.

The National Conference on Weights and Measures (NCWM) and National Type Evaluation Program (NTEP) have been concerned about production meeting type, protecting the integrity of the NTEP Certificate of Conformance since the inception of NTEP. A workgroup that was developed to assist NCWM with this effort has provided feedback and recommendations to the conference. The NCWM Board of Directors believes it has reached a point that the Verified Conformity Assessment Program can be launched.  Load cells traceable to NTEP certificates have been selected for the initial effort.

Any holder of an NTEP Certificate of Conformance for a device type listed above must comply with the program. Again the program will begin with load cells.

The PMT and VCAP are administered by two different organizations. Although similar, PMT is a manufacturer program developed by manufacturers, where VCAP is a regulatory requirement developed by NCWM.

No.  The certification body report must state compliance with VCAP.  The PMT and VCAP are similar but not identical.

No, while the ISO 9000 series quality standards and VCAP share a number of common features, ISO certification is not required.

No. Although there are some similarities, VCAP differs in its requirements. Therefore, ISO certification alone is not an acceptable substitute.

The CC holder is responsible for providing proof of VCAP certification, by a certification body, to NTEP. NTEP will not pay any costs associated with accreditation, audits, testing or certification.

In the eyes of NTEP, the CC holder is responsible for the product, including taking responsibility for assuring that production devices meet type.  NTEP expects the CC holder to take responsibility for the integrity of the certificate and product (device, instrument, main element, component, etc.).  NTEP is expecting private label certificate holders to verify with the manufacturer under contract that VCAP requirements are being met.  It is expected CC holders will have QA procedures in place, including controls over the supplier, purchase and compliance of the product covered under the private label agreement.

If you are the manufacturer of the device, there are a number of requirements.  You may already comply with most or all of them.  They include:

1. A Quality Management System that governs the design and manufacture of the device.  This Quality Management System must be documented in your Quality Manual.
2. Production and testing equipment and facilities necessary for the production and subsequent testing of the device.
3. You must identify those metrologically significant components (MSC) used in the device.  These are the components, materials, processes, and software that have an effect on the performance of the device.  It is up to you as a manufacturer to identify these items.  To determine whether an item is metrologically significant or not you must ask whether a change in the characteristics of that item will affect the performance of the device.  If the answer is yes, then the item is metrologically significant.
4. You must possess and use appropriate statistical tools or methods to ensure that the processes used to manufacture the device are in control.  This is often referred to as statistical process control and is a means to determine whether your processes are consistent and repeatable.
5. An appropriate sampling plan along with the required acceptance criteria for testing of the device.  The sampling plan that you choose must be traceable to a nationally recognized quality standard.  Optionally, you may use the sampling plan that is presented in Appendix A of the VCAP program description.
6. Possess the required operators’ manual and calibration procedures for all appropriate production and testing equipment.  Of course, you must not only possess these manuals, you must also ensure that your operators are familiar with them and follow the procedures contained within them.
7. A system to deal with nonconforming material and components, whether you purchase them or build them yourself.  This system must deal with the identification, control, and disposition of these items.
8. Adequate controls over suppliers to ensure the material or components they supply meet the necessary requirements.
9. A corrective action system designed and implemented to handle noncompliant or nonconforming material and components.
10. An engineering change system to control engineering design changes that affect metrologically significant components.
11. A document and data control system to document, record, and distribute to affected parties changes affecting metrologically significant components.
12. A production control system that manages changes that affect metrologically significant components.
13. A system that identifies and traces metrologically significant components.
14. A training system for personnel with documentation to verify that the appropriate training has taken place.

Compliance with the VCAP can be verified by submitting to a VCAP audit of your manufacturing / testing facility by a VCAP auditor. The auditor will verify that the previously mentioned quality and control elements exist are documented, and that the appropriate procedures are being followed. The auditor also verifies that the proper equipment needed to test and calibrate the devices you manufacture is present, sufficient for the task, and that they are being properly calibrated and operated. The audit will also include testing of a randomly selected device. For that reason, it is best to schedule the audit at a time when devices are available for testing.

For clarification, a change to 3.1 was made so it now reads:  For new certificate holders, Eensure that VCAP certification has been met completed, within a one year cycle of  the first maintenance fee, but not to exceed 18 months (example: if VCAP NTEP certified in July 2011, VCAP certification would be required by November of the following year 2012).  Section 3.2. has been deleted.

To perform a VCAP audit, the auditor must meet certain requirements. First, the auditor must be part of a certification body that is accredited by ANSI-ASQ National Accreditation Board (ANAB). The certification body must have accreditation to Standard Industry Classification (SIC) codes 3596 and 3821 or Sequence Number 847 NAICS, US Code 333997, Scale and Balance Manufacturing defined in the 2007 North American Industry Classification System or equivalent accreditation. There are several certification bodies that have auditors qualified to perform VCAP audits.  We cannot make any specific recommendations.

The NCWM Board has decided not to publish a list of certification bodies and/or auditors as it could appear the NCWM is recommending the companies or individuals.

It has been reported that the SIC codes and NAICS codes used are outdated.  Manufacturers are working to identify the correct codes.  This issue should not be a show stopper because the VCAP document already has the words “or equivalent”, recognizing other documents.

You are responsible for making certain that your supplier complies with the VCAP program. If your supplier fails to conform, their NTEP CC will ultimately become inactive as well as your private label certificate (if you have one). One way to make sure your supplier complies is to ask that you receive a copy of the VCAP auditor’s report.

The CC holder is responsible for assuring a documented quality management system, meeting VCAP requirements are in place, and providing NTEP with a certification body audit report containing a clear statement of compliance with VCAP.

The certification body is the organization that provides the auditor that performs the VCAP audit. It is the certification body that sends the auditor’s report to NCWM to show compliance with VCAP. The requirements for this report are listed in section S.1.c of the Administrative Policy as shown in NCWM Publication 14.

The VCAP audit is site specific. If there is more than one site where the testing of the device takes place, then each site must be audited. If the site does not perform any activities that affect the performance of the device and does not perform any device testing, it does not need to be subjected to a VCAP audit.

To ensure compliance with VCAP, the auditor may need to audit more than one site (for example: testing, control, manufacturing) if they are at different locations. For clarification, the following changes to the sentence under the first paragraph of S.1.c. and the definition were made during the NCWM Annual Meeting in July, 2009:

The Verified Conformity Assessment Program audit will be a site specific verification that will focus on the site that controls testing of the device at one or more sites as required to verify compliance.

Control Facility:  The control facility is the facility that is in control of the product before it goes into the marketplace, which could be one or more sites.

In this case, the factory has been identified as the control facility.  VCAP also requires that the CC holder have a documented quality management system governing the design and manufacture of the device.  The management system you describe may work and meet the requirements if adequate control can be verified.  Documentation of the quality management system and the decision of your auditor based upon the documentation and verification that the plan is working is critical, as an auditor may choose to conduct an audit at one or more sites to verify compliance.  It is important to recognize that Section 1.4 addresses the sampling plan and testing of the finished device covered by the NTEP certificate.  The sampling plan applies to the device covered by the NTEP certificate, not the metrologically significant components.

No.  For example, if your company manufactures five different families of load cells each with its own NTEP Certificate of Conformance you must only submit to one VCAP audit.  Successful completion of the VCAP audit will apply to all five NTEP Certificates of Conformance.  During the audit, the auditor will know what NTEP Certificates of Conformance you are being audited for and will take the necessary steps to ensure that all are covered.  If, for example, you make load cells of different capacities, the auditor will ensure that you have testing equipment sufficient to apply the appropriate test loads to each model of load cell that you manufacture.

The basic concept of NTEP is that by accepting an NTEP Certificate of Conformance (CC), each NTEP CC holder agrees to continue to manufacture and sell devices that meet the current requirements of NIST Handbook 44 and the requirements described in the NTEP CC. Devices must show, by their markings, that they have an NTEP CC, and what tolerance values, class etc. the device meets. The NTEP CC holder has submitted a device which is typical of the production devices that will be manufactured and sold subsequent to the issuance of the NTEP CC. The intent of VCAP is to ensure that the NTEP CC holder has an acceptable Quality Management System in place for the requirements that must meet Influence Factors. In the case of load cells this is mainly temperature effects on linearity, hysteresis, span, repeatability, zero (vmin or MDLO), and creep. This can also include effects of barometric pressure and in the case of digital load cells, effects of variation in power supply parameters.

The simple answer is that the audit, by the certification body, which is based on the parameters described in the VCAP procedures, will be the basis of evidence that the NTEP CC holder is capable of meeting those requirements. The VCAP procedure is loosely based on ISO 9001:2000. The procedure describes an audit of the quality management system, with an addition of objective evidence, in the form of audits on devices that indicate the capability of the NTEP CC to meet the influence factor requirements. The audits of devices are conducted by the NTEP CC holder. If the auditor is convinced that the VCAP requirements are being met then a certificate indicating compliance would be issued and submitted to NTEP for review.

NCWM Publication. 14, Weighing Devices, Load Cells describes the testing accuracy required in Section C.  In part it states:

"The error in the test process for force transducer (load cell) evaluations may not exceed one-third of the tolerance applied at the force transducer (load cell) (0.7 times the tolerance for the weighing system).  The important characteristics for the test process for force transducers (load cells) (and indicators) for compliance with the influence factors requirements is linearity and repeatability, not absolute accuracy.  This means that the accuracy of the applied load is not critical, but the change in performance of output of the force transducer (load cell) (or indicator) under the same load but different environmental conditions is important.  Consequently, the uncertainty in the reference standard may not be significant provided the uncertainty of the linearity of the total system is within one-third of the tolerance to be applied to the force transducer (load cell)."

So it is clear what the general requirements are for test equipment.

There are many different methods to achieve quality in a load cell. This could extend from testing each device to auditing one sample from a lot. This could also extend from following the test procedures described in Publication 14 for every load cell, to reducing the time and load to a minimum value to properly characterize the device under test. NTEP is not attempting to dictate the quality management system nor the testing or auditing methods used to ensure that devices meet the requirements. This will be up to each of the NTEP CC holders to determine. It will then be up to the auditors to determine that the VCAP requirements are being met. In some cases this may require some investment in equipment upgrades, calibrations, etc., however; it is the belief of NTEP that this equipment and quality management system should already be in place, and should not present a significant burden on the NTEP CC holders.

If the product does not meet applicable NIST Handbook 44 requirements, including tolerances, it cannot be sold for use in a commercial (legal for trade) application.

VCAP does not cover every component of a device, only those that are metrologically significant and are susceptible to T.N.8 influence factors.  A manufacturer can chose to consider the complete device or main element to be metrologically significant.

The following change was made to paragraph 1.2.3.  during the NCWM Annual Meeting in July, 2009: 

1.2.3. Metrological integrity is maintained by verification that the applicable characteristics of those components identified as metrologically significant are unchanged from those used in the device certified.  Verification can also take place by testing of the finished device to verify that it is unchanged from the device certified.

It is up to the manufacturer to declare a component a MSC.  That could be an individual component or the assembly in which the component is used.

Yes, they are separate requirements.  Section 1.2 addresses metrologically significant components (MSC) and requires a change to a component identified as a metrologically significant part of the device to be verified.  Section 1.2.3 recognizes that verification can take place by testing the finished device.  Section 1.4 addresses the sampling plan and testing of the finished device covered by the NTEP certificate.  The sampling plan applies to the device covered by the NTEP certificate, which can be the load cell.

The sample sizes are based on annual production per Certificate of Conformance (CC).  If the CC lists several models or versions in a family (capacity, size, enclosure style, etc.), you could combine the yearly forecast for all to determine the total production quantity and then test a mix of the versions based on the minimum sample size.  Section 1.4.1 also allows other national recognized quality standard sampling plans, that are Acceptable Quality Level (AQL).  The idea behind the AQL information is based on performing sample inspections of a fixed lot size of a product or part.  Again, in the case of VCAP, the lot size is the annual product number per CC. So each CC stands alone, then the annual production of the cells per each CC should be determined, then the sampling plan is declared.  After determining the number to be tested, selection and testing must be conducted in accordance to NCWM Publication 14.

For clarification, a change to 1.4.2. was made, so it now reads: Devices shall be selected and tested in accordance to NCWM Publication 14 as designated by the established sampling plan.

To ensure compliance with VCAP, the auditor may need to audit more than one site (for example: testing, control, manufacturing) if they are at different locations. For clarification, the following changes to the sentence under the first paragraph of S.1.c. and the definition were made during the NCWM Annual Meeting in July, 2009:  The Verified Conformity Assessment Program audit will be a site specific verification that will focus on the site that controls testing of the device at one or more sites as required to verify compliance.

Control Facility:  The control facility is the facility that is in control of the product before it goes into the marketplace, which could be one or more sites.

For clarification, a change to 3.1 was made so it now reads:  For new certificate holders, Eensure that VCAP certification has been met completed, within a one year cycle of  the first maintenance fee, but not to exceed 18 months (example: if VCAP NTEP certified in July 2011, VCAP certification would be required by November of the following year 2012).

Section 3.2. has been deleted.

Any nonconformities, be it major or minor, must have corrective action taken within 90 days. The difference between the two is that a minor noncomformity can be verified by the auditor via paperwork and does not require a revisit by the auditor whereas a major non conformity does require a revisit. Each nonconformance is unique but this is a general understanding. At the time of the audit, the auditor may advise you of whether a follow up audit is required or if only a review of objective evidence is required to show that the non conformities have been addressed.

Compliance testing must represent the test requirements as shown in Publication 14.

NCWM Publication 14, Administrative Policy, Section S.2 states the certificate(s) will be declared inactive. NTEP anticipates a certificate could also be withdrawn.

No. For example, if the auditor finds that you have sufficient production equipment to produce your full line of load cells but have testing equipment that can only test up to 5000 pounds, then only those load cells that require performance testing to loads greater than 5000 pounds will not comply. Failure to obtain the required testing equipment could ultimately result in the loss of the NTEP Certificate that covers the cells with capacities greater than 5000 pounds.

In response to this concern, the NTEP Committee has implemented a “Systems Audit Checklist,” which the auditor is required to complete and submit to NCWM.