What is a commercial scale or meter?
In Minnesota, a commercial scale or meter is defined as any scale or meter used to buy or sell commodities or services for which the price is determined by the measurement on that device. The Weights and Measures Division inspects commercial scales and meters. If a scale or meter passes inspection, the investigator attaches a dated approval scale to the device. The investigator rejects any commercial scale or meter that is not accurate, not of commercial quality, or not suited for its intended purpose.
How do I need to know if I need a commercial quality scale or meter?
You must have a commercial quality scale if you buy or sell a commodity or service by weight. For example, you must have a commercial quality scale to sell candy, produce, nails, beads, seed, bait, oxygen, or other commodities by weight. Your scale must also be of commercial quality if it prints price labels for meat, deli, bakery, produce, or other items; if it is used to buy metal, jewels, or any other commodity by weight; or if it is a shipping or laundry scale, or is used to determine the price of any other service.
You must have a commercial quality meter if you buy or sell a commodity or service by volume. For example you must have a commercial quality meter to sell propane, gasoline, diesel, heating oil, kerosene, or other liquids or gases by volume. Your meter must also be of commercial quality if it is used to buy cooking oils, lubricants, or other liquids; or if it is used to determine the price of a service such as de-icing a plane.
How do I know if my scale or meter is of commercial quality?
Any commercial scale or meter manufactured or installed after January 1, 1996 must have a National Typed Evaluation Program (NTEP) Certificate of Conformance (COC) issued by the National Conference on Weights & Measures. Individual components of a weighing or measuring system may be covered under one NTEP COC, or each component may have its own NTEP COC. New scales and meters which do not have all components covered by an NTEP COC are not considered commercial quality and will be rejected. Scales and meters manufactured and installed before January 1, 1996 may be grandfathered in if they met the requirements of NIST Handbook 44 at the time of their installation and have remained in continuous use without being moved.
In addition, any commercial scale manufactured after January 1, 1986 must be labeled Class III if it is commercial quality. It will have an identification plate with the serial number, the manufacturer's name, a model number, maximum capacity, number of measurement divisions, and size of the smallest measurement.
Commercial quality scales manufactured before January 1, 1986 may be labeled class III and have an identification plate as described above. A scale manufactured before 1986 which has no class marking is commercial quality if it has a manufacturer's name, serial number, maximum capacity listing, and measurement division size printed on it.
To be of commercial quality, mechanical scales must have a zero which requires a tool to adjust and electronic scales must have a means for sealing the calibration mechanism.
Bathroom scales, baby scales, scales marked Not Legal for Trade, and mechanical scales with thumbscrew zeros or other zeroing mechanisms which can be adjusted without a tool, are not commercial quality scales and must not be used for commercial transactions in Minnesota.
How do I know if my scale or meter is suitable for its intended use?
A scale is suitable for its intended use if the minimum load which will be weighed on it is 20 measurement divisions or more. A scale whose smallest division is 0.05 lb. is suitable for minimum loads of 1 lb. or more. US Department of Agriculture requires .01 lb. or smaller divisions for meat scales with label printers. Mechanical meat scales may have divisions no larger than 1 ounce. For most other applications, scale divisions of 1 ounce, or .01 lb. are adequate.
A meter is suitable for retail use if the value of its smallest unit of indicated and recorded delivery is either 0.5L or 1 pint.
A meter is suitable for wholesale use if the value of its smallest unit of indicated and recorded delivery is either 0.5L or 1 gallon.
After January 1, 2007, commercial meters had to meet new NTEP requirements related to flow rate before they could earn a certificate of conformance. On meters manufactured after January 1, 2007, the smallest value of indicated and recorded delivery is:
- 0.5 L (0.1 gal) on meters with a rated maximum flow of 750 L/min (200 gal/min) or less;
- 5 L (1 gal) on meters with a rated maximum flow of more than 750L/min (200 gal/min);
- 5 L (1 gal) on meters with a rated maximum flow of 375 L/min (100 gal/min) or more used for jet fuel aviation refueling systems.
When will my scale or meter be tested?
If the company which sells you the scale or meter has service agents registered with the Weights and Measures Division, they will notify the Weights and Measures Division when they place the device in service. If you buy a scale or meter off the internet, from a private party, or from a company with no registered service agents, you are responsible for notifying the Weights and Measures Division of the purchase, and you must not use the scale until it has been placed into service by either a weights and measures investigator a registered service person. If a Weights and Measures official cannot schedule an inspection in your desired time frame, you can download a list of companies with registered service agents.
When buying a used scale or meter, do not assume that a device which has last year's approval sticker will pass inspection. Have a reputable service company examine the scale or meter before you buy it; or make an agreement with the seller before the sale about what will happen if the scale is rejected.
After the initial inspection, a commercial grocery, food or hardware scale may be inspected every 3 years or in response to a consumer complaint. All other commercial scales and meters may be tested annually or in response to a consumer complaint.