ISO 4112:2025
(Main)Cereals and pulses — Guidance on measurement of the temperature of grain stored in bulk
Cereals and pulses — Guidance on measurement of the temperature of grain stored in bulk
This document gives guidance on the measurement of the temperature of grain stored in bulk in storage buildings, silos or any other warehouses, including detection apparatus, temperature sensors, layout of temperature probes, digital display of results and measurement operation steps.
Céréales et légumineuses — Directives générales pour le mesurage de la température des grains entreposés en vrac dans les installations de stockage
La présente Norme internationale donne des directives générales pour le mesurage de la température des grains au cours de leur entreposage en silos ou dans toute autre installation de stockage en vrac.
General Information
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Standards Content (Sample)
International
Standard
ISO 4112
Third edition
Cereals and pulses — Guidance on
2025-06
measurement of the temperature of
grain stored in bulk
Céréales et légumineuses — Directives générales pour le
mesurage de la température des grains entreposés en vrac dans
les installations de stockage
Reference number
© ISO 2025
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Apparatus and system . 2
6 Procedure . 3
6.1 Positioning the measuring points .3
6.1.1 Grain temperature sensors .3
6.1.2 Warehouse temperature sensors .3
6.1.3 Air temperature sensors .3
6.2 Temperature readings .4
6.2.1 Frequency of readings .4
6.2.2 Particular requirements for ventilated warehouses .4
7 Temperature records . 4
7.1 General .4
7.2 Calibration .4
Annex A (informative) Temperature-reading devices . 5
Annex B (informative) Layout of temperature measuring points . 6
iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
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with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
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Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 4, Cereals
and pulses.
This third edition cancels and replaces the second edition (ISO 4112:1990), which has been technically
revised.
The main changes are as follows:
— the term “warehouse” and its definition have been added;
— the apparatus for temperature measurement have been modified;
— the temperature sensors and thermometric system for stored grain have been added;
— the layout of temperature measurement points has been modified;
— the wireless communication technology and networking technology have been added;
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
Introduction
Grain storage plays a crucial role in ensuring food security. The physiological processes which occur within
a mass of stored grain are accompanied by the emission of heat, and the external environmental factors
(e.g. hot climate, ventilation) can also cause grain temperature changes in bulk storage. As a result, the
temperature of the grain can reach a level at which serious permanent deterioration in the commercial,
technological and food properties of the grain will take place. It is therefore necessary to detect and measure
any overheating during storage and to take immediate remedial measures, such as ventilation and cooling,
since late remedial measures will, in most cases, have no effect.
In bulk storage, such damage is often in the initial stages, localized and affects only a small proportion of
the grain stored. However, such damage, although localized in the initial stages, can spread to other regions
of the stored grain if not checked in time, easily resulting in large-scale mildew contamination and pest
infestation. The consequences of any overheating, even if it is localized, are always serious since it is possible
that a batch of the grain will have to be marketed at reduced prices or can even become unsaleable because
of the presence of damaged grain. Because of the ever-increasing demand for grain of good quality and the
prolonged periods of bulk storage, it is important to check the temperature of the grain frequently. The use of
thermometric equipment, based on a large number of measuring points, is an appropriate technique to meet
this objective. On the other hand, manual temperature measurement is also an effective way to monitor the
health status of bulk grain in horizontal warehouses, even for long-term storage.
Thermometric equipment is also necessary to enable correct cooling by ventilation to be carried out. Such
cooling, using successive steps of 5 °C to 7 °C, can be economically employed in cold climates. At 0 °C, the
physiological activity of grain is insignificant even when its moisture content is close to the maximum
recognized internationally.
v
International Standard ISO 4112:2025(en)
Cereals and pulses — Guidance on measurement of the
temperature of grain stored in bulk
1 Scope
This document gives guidance on the measurement of the temperature of grain stored in bulk in storage
buildings, silos or any other warehouses, including detection apparatus, temperature sensors, layout of
temperature probes, digital display of results and measurement operation steps.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
grain
cereal grains and/or seeds of pulses
3.2
bulk storage
storage of grain (3.1) unpackaged in large quantities
Note 1 to entry: For example, in silo, squat silo and grain storage buildings.
3.3
warehouse
structure or building for grain storage with basic requirements for safe storage
EXAMPLE Silo, squat silo, horizontal warehouse, large size horizontal warehouse, multi-storied warehouse.
3.4
thermometric system for stored grain
system for monitoring the stored grain temperature in bulk storage (3.2), which is implemented by means of
computer, communication network and electronic technology
4 Principle
Placing a series of thermometric probes throughout the mass of stored grain to detect or monitor changes in
temperature.
5 Apparatus and system
The type of apparatus and measurement system or installation shall be suitable for the size and shape of the
warehouse as well as the storage period. For example:
a) for short-term storage, use the following apparatus:
1) a portable apparatus, for small warehouses;
2) a semi-fixed or retractable apparatus, for horizontal warehouse, i.e. warehouses with extensive
floor areas and limited height;
3) a permanent installation, for vertical warehouse (silos);
b) for long-term storage, use a measurement system.
Temperature measuring points should be arranged for the whole warehouse according to a certain standard
(6.1) and connected via a wired or wireless communication technology. Computers or other detection
apparatus should be used for monitoring the grain temperature in a warehouse or a grain depot, resulting in
the record, display, query and analysis of the temperature value.
The apparatus (system) shall comprise the parts given in 5.1 to 5.5.
5.1 Thermometric cables (probes), one or more, usually consisting of a rigid tube or flexible cable (5.2)
with one or more temperature-sensing devices (5.3), together with their respective output conductors,
which are housed in the tube or cable. When the probe is buried in the mass of grain, its response time to
reach a steady temperature reading shall not exceed 3 min.
The materials used to fabricate the thermometric probes shall be resistant to products employed for
fumigation and to damage by rodents.
Flexible cable suspended in silos should be anchored at the bottom of the warehouse to prevent dislocation
during loading. The upper ends of cables should be anchored on the silo roof through the reserved holes on
the roof or hung on the hooks inserted the ceiling. The upper ends of the flexible cables can be connected to
the control cabinet.
5.2 Flexible cables or rigid tubes, of appropriate length and diameter, made of glass fibre, metal or other
suitable material and, particularly for vertical warehouses, having the strength and rigidity to resist the
very high tensile and compressive forces which occur when the warehouse is filled and emptied.
NOTE Forces on the tubes or cables increase with their diameter, depth of burial, and movement of the grain
during loading and unloading. Tensile forces of up to 50 kN can occur. A small diameter has the effect of reducing the
strain at fastening points and simplifying the anchorage system. Conversely, larger diameters give greater rigidity,
which is particularly important for very dee
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