Bentall Rowlands Storage Systems Limited is a leading UK manufacturer in complete storage and processing equipment solutions for the agricultural and industrial markets.

1. B
entall Rowlands Storage Systems
Limited is a leading UK manufacturer
in complete storage and processing
equipment solutions for the
agricultural and industrial markets.
We offer a wide range of galvanised
steel silos and hoppers, water tanks,
catwalks and platforms, material
handling equipment, cleaning and
grading and weighing and drying systems that are assembled
worldwide.
With the capabilities to design, manufacture, supply, and install
storage systems from an extensive range of products, we provide
a comprehensive end-to-end solution, which can be designed to
any specific clients’ requirements.
We have designed and installed silos worldwide in countries
that include the UK, Kenya, Thailand, Holland, France, Germany,
Ukraine, Malawi, New Zealand and many more.
Kevin Groom, Technical Director says, “Our storage systems
are individually designed for all clients. Each project has a
bespoke design that is sure to match, if not exceed clients’
expectations. We are extremely proud of the projects that we have
undertaken in these geographically challenged areas, proving
that whatever the specification, we are sure to provide the most
suitable design necessary.”
Moisture levels and consequences
Getting the moisture levels right in a silo can be challenging but
it is essential that the target level is reached within the shortest
possible time. If this does not occur, the results would be the
formation of mycotoxin and quality degradation. The main causes
of spoilage in stored grain are fungi, insects and mites.
Fungi is one of the main consequences of a variety of different
moisture contents and temperatures stored in grain. In order to
control this, a principal method known as drying and cooling
needs to be put in place. No storage fungi will grow below a
moisture content of 14.5 percent but they do continue to grow
MOISTURE CONTROL
FSTORAGE
by Louise Smith and Nick Carter, Bentall Rowlands, UK
IN STORAGE
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3. slowly at near 0°C. This means that cooling alone is not sufficient
but the lower the temperature, the slower the rate of growth.
Another nuisance is storage mites which breed rapidly under
favourable conditions and will cause direct damage to the grain
by hollowing out oilseeds or eating the germ. Physical control
methods are used for mites. If the grain is dried to 14.5 percent
moisture content then the mites are unable to breed. If you
cool the grain to 5°C, this can also help to prevent the build up
of them. However, if you are storing oilseed rape, this is less
susceptible to insect attack than cereals.
This will protect the grain bulk, but during winter, the moisture
content on the surface of the grain may increase, meaning that
mites can become a problem in the surface layer.
A final problem relating to moisture control is insect presence
and infestation problems. These can occur where bad hygiene is
present. Good store hygiene is therefore an important first step in
eliminating these pests. Both the building structure and the stored
grain should be monitored using traps. Traps within the grain
bulk should be positioned approximately 5 – 10cm below the
surface to monitor any insect species with different behaviours.
Stores should be thoroughly cleaned prior to the intake of
product. It is extremely important for eliminating any sources
of contamination from storage fungi, insects and mites. Store
preparation is a key stage in ensuring the safe storage of grain.
Whether the grain is being stored temporarily, or for a longer
period of time, this is a necessary step that needs to be followed.
Good store preparation needs to work in conjunction with
obtaining and maintaining the target temperature and moisture
content. This will ensure the safe storage of grain.
There are a number of key features of a good grain store,
including:
• Clean
• Dry
• Well ventilated
• Correctly functioning
equipment
• Proofed against rodent and
bird entry
• Watertight roof
• No physical contaminants
• Secure
How best to store your grain
A steel grain storage silo is a fully bolted vessel and while not
being airtight they are water-tight. On all the joints, sidewall and
roof, a sealing mastic is used to prevent against the ingress of
water. The roof sheets overhang the eaves to ensure snow and
rain cannot gain access. At the peak of the silo the roof sheets fit
under the collar or petal and are sealed with blanking plates. As a
manufacturer of silos we will give advice on how to seal the silo
at base level.
All of these design features, tried and tested, over many years
of product development are in place to stop the external moisture
from reaching the grain. The level of moisture and temperature
of grain in a storage silo comes from good housekeeping. It
is very important that the operators of storage systems, both
on-farm and industrial stores understand the levels required to
maintain the quality of the grain being stored.
There are a number of good technical papers available and it is
good working practice to re-view. As the grain comes into the
system it is important to know the level of moisture. From this
the operator will know if the grain will require drying. There are
many forms of grain dryers such as in-bin systems or continues
mixed flow. The in-bin systems tend to use gas as a fuel and can
be limited on the hourly capacity whereas the mixed flow dryer
can run on gas, fuel oil and solid fuels.
Different types of fungi live at different moisture contents and
temperatures in stored grain; Storage fungi can grow on cereals
from about 14.5 percent moisture content upwards and may cause
heating and loss of germination. Once the grain enters the storage
silo or flat floor storage system it is important that the checking
of grain does not stop. Most modern silos are supplied with
ventilation systems. The concept of these systems is very simple
and has been used for thousands of years.
By passing air through grain it is possible to not only reduce
the temperature of grain but also to reduce the moisture content.
There are two main types of ventilation systems in silos: either a
trench system or full floor. These systems allow low volumes of
air to be pushed into the silo with a ventilation fan either Axial or
Centrifugal.
The fans are connected to either the silo base for a trench
system or to the silo sidewall for a full floor system. The
pressurised air then moves up through the grain and thus lowers
the temperature of the grain. This action will also cool air dry the
grain and lowers its moisture content. Within the silo it is possible
to have a number of temperature monitoring cables. These cables
have a series of sensors which will measure the temperature of
the grain in a given area. The system will allow the operator to
see what is happening within the silo.
As the air moves through the grain it will evaporate water from
the grain, helping to reduce the moisture content of the grain. The
moisture, which has been absorbed by the air, then passes into the
open roof area of the silo. It is important with silos to ensure that
there is good free air movement around this area. This will allow
the moisture-laden air to simply vent to the atmosphere. The
design of the roof vent is very important. Not only should it allow
good airflow but must stop birds, rodents, snow and rain getting
in. As you can see from the photograph this vent is designed for
free movement of air but by being triangular it prevents rubbish
collecting around its face. This is a common problem with roof
vents and you can see areas of rust building up in this area.
Another way to ensure good airflow around the internal open
area is to use roof exhaust fans. These are used to equalise the
temperature of the air within the internal area and atmosphere. By
using the design shown in the photograph they can easily be reached
for maintenance or to be closed when using a fumigation system.
On our range of silos we use a dimpled eave-retaining clip. This
clip gives a 2mm gap between the roof sheets and the sidewall
sheets. Tucked well under the eaves it is designed not only to help
with air movement around the internal area but also to allow any
beads of condensation which may have formed on the inside of
the roof structure to simply run off.
www.bentallrowlands.com
STORAGE
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4. GROWING INTO
THE FUTURE
TAKING CARE
ADDING VALUE
SOLUTIONS FOR HANDLING
AND STORAGE OF
GRAIN AND SEED
Cimbria develops and manufactures an
entire range of equipment and solutions
for seed processing.
Thorough technical engineering experience
and in-depth product knowledge enable
us to supply solutions for cleaning, grading
and treatment of various seed and grain
products.
Special focus is kept on effective sorting
and cleaning, gentle handling, crop-purity,
safe and dust-free operation and low
running costs.
CIMBRIA.COM
CIMBRIA UNIGRAIN A/S
Praestejorden 6 | DK-7700 Thisted
Phone: +45 96 17 90 00
E-mail: unigrain@cimbria.com
CONVEYING | DRYING | SEED PROCESSING | ELECTRONIC SORTING | STORAGE | TURNKEY