Everything you want to know about Commercial Grain Analyzers

This handbook includes instructions and procedures for developing grain samples used to test commercial grain moisture meters, field inspection and testing instructions, and requirements for testing commercial grain moisture meters.

Examination of Grain Moisture Meters Using Air-Oven Reference Method Transfer Standards/Part 1: Laboratory Grain Sample Preparation and Testing; Part 2: Field Inspection and Examination

NIST Handbook 44 contains instructions for how a device used commercially must be designed that are directed particularly to the manufacturer of the device, paragraphs that address how the device should be used that are directed particularly to the owner and operator of the device, and these and other paragraphs (General, Application, Notes, Tolerances, Definitions and Appendices) are used by manufacturers, users, owners, and by W&M Inspectors to inspect and test the device.  

NIST Handbook 44, Section 5.56(a) includes Specifications, Tolerances, and Other Technical Requirements for commercial National Type Evaluation Program (NTEP) grain moisture meters and applies to all NTEP meters and any grain moisture meter manufactured or placed into service on or after January 1, 1998.

NIST Handbook 44, Section 5.56(b) includes Specifications, Tolerances, and Other Technical Requirements for commercial grain moisture meters and applies to all non-NTEP meters and any grain moisture meter manufactured or placed into service before January 1, 1998.

NIST Handbook 44, Section 5.57 includes Specifications, Tolerances, and Other Technical Requirements for commercial near-infrared grain analyzers and applies to near-infrared (NIR) grain analyzers; that is devices used to indicate the constituent values (other than moisture content) of grain using near infrared reflectance or transmittance technology.

Link to Publications search showing all editions of NIST Handbook 44 >>

NCWM NTEP Publication 14 contains the U.S. technical policies, checklist, and test procedures for type approval of commercial grain analyzers. An evaluation of a commercial grain analyzer type is required before it can be sold in most States in the U.S.

The OIML requirements for grain analyzers are outlined in two documents: OIML TC17/SC1 R59, “Moisture Meters for Cereal Grains and Oilseeds,” and OIML TC17/SC8 R146, “Protein Measuring Instruments for Cereal Grains and Oilseeds.” Many countries require that a manufacturer’s device undergo an evaluation before it can be sold in their markets.

1. Grain Moisture Meter (GMM) Series Part 1 – Overview of GMM Series Topics November 2006 (Article C-005)
2. The Economic Impact of Errors in Moisture Measurements Part 2, Grain Moisture Meter Series – March 2007 – (Article C-006)
3. Grain Moisture Meter (GMM) Series Part 3 - Grain Moisture Meter Measurement Technology - Near Infrared – September 2007 – (Article C-007)  (Also see article under “Technology and Operation”)
4. Grain Preparation, Maintenance and Storage of Grain Transfer Standards, Equipment and Apparatus, and Field Test Procedures – September 2008 – (Article C-008) (Also see under Test Procedures and Tolerances)

1. Grain Moisture Meter Test Methods and Tolerances – May 2011 – (Article C-009)
2. Testing Grain Moisture Meters (GMMs) – May 2004 – (Article C-003)
3. Near Infrared (NIR) Device Inspection and Moisture Basis – November 2002 – (Article C-001)
4. Grain Moisture Air-Oven Reference Methods in the United States – November 2012 – (Article C-011)
5. Determining Reference Test Weight per Bushel Value of Grains – September 2013 – (Article C-012)
6. Grain Preparation, Maintenance and Storage of Grain Transfer Standards, Equipment and Apparatus, and Field Test Procedures – September 2008 – (Article C-008)

1. What do Grain Moisture Meters Measure and How are They Calibrated? – September 2006 – (Article C-004)
2. A New Generation of Grain Moisture Meters – February 2012 – (Article C-010)
3. Grain Moisture Meter (GMM) Series Part 3 - Grain Moisture Meter Measurement Technology - Near Infrared – September 2007 – (Article C-007)

Commercial grain analyzers are devices that measure the dielectric or near-infrared response of grain to determine various constituent values, such as moisture and protein content. They provide percentage measurements for moisture, protein, and other factors. These analyzers are deemed commercial because they play a crucial role in pricing grain; the measurements they yield, such as moisture and protein levels, are used to calculate discounts applied to the price per bushel, ultimately affecting the price the seller receives. Below are pictures of grain analyzers:

Commercial grain analyzers measure various grain constituents, such as moisture and protein content. Discounts on the price per bushel of grain are applied at the time of sale based on these measurements, as well as other factors. Discounts are reductions in the price per bushel that the seller ultimately receives. 

Two common types of discounts are drying discounts and shrinkage discounts. A grain buyer often needs to dry grain above the desired moisture content to prevent mold during storage. The cost of drying the grain, or the drying discount, is determined by the moisture measurement at the time of sale. For example, if a buyer intends to purchase corn at $4.00 per bushel, targeting a moisture content of 15%, they will reduce the price per bushel if the grain's moisture level exceeds that target.

Additionally, grain that is too moist may be stored with aeration, which will experience shrinkage during storage.  The cost associated with this shrinkage, or shrinkage discount, is also calculated based on the grain's moisture content at the time of sale.

Errors in measuring moisture, protein, and other grain characteristics can lead to significant financial losses for either the seller or the buyer.

According to the June 1997 Grain Moisture Meter Questionnaire and state reports of subsequent changes, 19 states have implemented such programs. These states are Arkansas (AR), Colorado (CO), Florida (FL), Georgia (GA), Illinois (IL), Indiana (IN), Iowa (IA), Kentucky (KY), Louisiana (LA), Maryland (MD), Mississippi (MS), Missouri (MO), Nebraska (NE), North Carolina (NC), Pennsylvania (PA), South Carolina (SC), Tennessee (TN), Virginia (VA), and Wisconsin (WI).

Typically, official tests and inspections of commercial devices are managed within a state's weights-and-measures program. Some states permit other entities to conduct official tests and inspections of these devices, while providing oversight for those entities. The methods by which a state performs tests and inspections of commercial devices are detailed in its specific state laws.

States interested in establishing a commercial grain analyzer test and inspection program are encouraged to reach out to neighboring states with existing programs. This can provide valuable information regarding costs, space, and equipment needs. Additional details on laboratory and field equipment can be found in the NIST Handbook 159, "Examination of Grain Moisture Meters Using Air Oven Reference Method Transfer Standards."

Furthermore, newsletter articles on various test procedures are available on the OWM website under the "Pages by Topics" section.

The requirements can be found in NIST Handbook 44, specifically in Sections 5.56a and 5.56b, which cover grain moisture meters, and Section 5.57, which addresses near-infrared grain analyzers. These sections outline the specifications, tolerances, and other technical requirements necessary for testing and inspecting these devices. 

For more information, visit: NIST Handbook 44 - Current Edition

In the United States, the National Type Evaluation Program (NTEP) is the designated evaluation program. Most states have adopted NTEP into their laws and regulations, which means that manufacturers of commercial grain analyzers must have their devices evaluated by a type evaluation laboratory before they can be installed in any state. The NTEP requirements for grain analyzers are detailed in NCWM Publication 14, "Grain Moisture Meters and Near Infrared Grain Analyzers."

For more information, you can visit: https://www.ncwm.com/publications/ncwm-publication-14-grain-moisture-me…

The International Organization of Legal Metrology (OIML) oversees the international type evaluation program. Many countries require that a manufacturer's device undergo an evaluation before it can be sold in their markets. As a result, manufacturers of commercial grain analyzers must have their products evaluated prior to selling them in many of those countries. 

The United States has participated in technical committees to help develop international type evaluation requirements, leading to a harmonization of grain analyzer standards with U.S. requirements. 

The OIML requirements for grain analyzers are outlined in two documents: OIML TC17/SC1 R59, “Moisture Meters for Cereal Grains and Oilseeds,” and OIML TC17/SC8 R146, “Protein Measuring Instruments for Cereal Grains and Oilseeds.” 

For more information, please visit: https://www.oiml.org/

A discussion on the importance of grain moisture meter measurements and their economic impact, which will include the system of grain moisture measurements in the U.S., the economic impact of grain moisture measurements, and resources for States with grain moisture meter programs. (June 25, 2024)

OWM Info Hours: The Importance of Grain Moisture Meter Measurements