NTEP Approval: How Does It Relate To An Automatic Weighing System

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Mar 26, 2013

NTEP stands for National Type Evaluation Program.

It is administered by the National Conference of Weights and Measures and is endorsed by most states as being the benchmark to allow a device to be used as a legal for trade point of sale weighing device.

To get an NTEP approval (also known as a Certificate of Conformance (CoC) you must submit an application, conduct laboratory testing and in most cases field testing to verify accuracy and performance of the automatic weighing system (in-motion checkweigher, conveyor scale, etc).

There are weighment accuracy tolerances that must be met.

Testing of performance for these tolerances occur at temperature variations from 14º F to 104º F (environmental chamber), often in the field locations to prove industry usage, and permanence testing where they run up to 100,000 weighments across the scale between testing sessions to verify the device’s ability to remain accurate.

It is a VERY expensive commitment by the manufacturer of the device and in itself is a testament to the seriousness and commitment of the manufacturer to a given product design and weighing system application of that product.

Simply put: it often separates the ‘wheat from the chaf’ in the weighing industry giving the perspective buyer of an automatic weighing system the added assurance that the manufacturer who has a CoC on a device knows his stuff and is not only capable of building a high quality product, but has demonstrated it to his peers.

What is an automatic weighing system?

At its most basic,  it weighs products automatically without an operator to physically place product on a scale, record the weight, and then remove it.

Think of a conveyor line moving product.

Do you want a scale in that line weighing each product?

Or do you want to physically remove each product, place it on the scale, record the weight, and then replace the product back on the conveyor to weight 100% of the product?  Probably not.  Labor simply costs too much these days.

Automatic weighing systems basically fall into two categories, checkweighers and weigh labelers.

Checkweighers simply check the weight and often reject out of weight spec product, while a weigh labeler will do the same, but also will record the weight on a label or database of each individual product for use in the sales transaction.

A weigh labeler will handle various types of products including variable length, width, height, and weight (this is tougher to do), while a checkweigher is basically “tuned” to run one product (this is easier to do).

In NTEP testing, the difference is subtle but very distinct.

A weigh labeler must be calibrated, sealed (so you cannot change calibration), and then tested completely including temperature, field, and permanence, while a checkweigher may be calibrated before every test.

You could say ‘well, just get a checkweigher approval because it is easier to pass,’ and you would be right!

But hold on just a minute, if you got a checkweigher approval you would only be able to sell your automatic weighing system to check weigh, not to record variable weights on labels or databases as a bases for individual product sale.

It is also worthy to note that NTEP approval is not required of checkweighers while NTEP approval IS required of weigh labelers in most states.

Think of it this way, a checkweigher (with or without NTEP approval) is used to verify net weight labeling on something like cans of soup where every can is supposed to weigh the same net amount and the product more often than not is the same physical size.

The soup manufacturer is required to meet the National Institute of Standards and Technology’s Handbook 133 (Checking the Net Contents of Packaged Goods) requirements.

Basically, for the soup manufacturer, the regulatory people say “meet the H133 standards including Maximum Allowable Variation and we don’t care how you do it, just do it.”

The soup manufacturer will often install a checkweigher to assist them in making sure they meet the H133 standards.

The tray pack manufacturers are faced a more direct regulation requirement.

Each package weight may be different and all of them must be accurate.

A weigh labeler would be used for variable priced trays that could easily vary by several pounds in weight and physically be very different in terms of size and shape of product (chicken, beef, seafood, vegetables, etc.).

The labeler must still be accurate for all weighments and variations of products being chaotically run without calibrating (tuning) the scale to a specific product.

As with anything, there are limits to the variability, but the key idea is you can feed that chaotic (various) product to a weigh labeler with peace of mind.

The neat thing is, if you go through the extra tight and stringent work of NTEP-testing your automatic weighing system as a weigh labeler and add a simple easy-to-pass Maximum Allowable Variation test, you also get the checkweigher NTEP approval. This allows for listing both on the Certificate of Conformance (CoC).

Well this is a no brainer right?

Well not really, because if you submitted for NTEP approval only as a checkweigher you would be allowed to calibrate before each test and would not have to seal your calibration for the duration of the NTEP testing like you have to do on a weigh labeler.


Basically, when you look at automatic weighing systems, if there is no NTEP approval, BUYER BEWARE!!!!

You are considering purchasing a unit that has not been evaluated for performance, thus you may not even be capable of meeting any kind of tolerance at all, let alone being able to maintain its performance without constant “tuning.”

If the unit has a NTEP approval but does not specifically call out class III weigh labeler, you could be looking at a device that has proven it is capable of being “tuned” to weigh correctly for a given single product for a given temperature for a given period of time.

However, if you buy an NTEP approved weigh labeler, it IS a given that you are purchasing a unit that has been proven to be capable of accurately weighing a VARIETY of product, at a VARIETY of temperatures, for a long period of time without having to mess with calibration of the scale system to make sure it is working properly.

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