Serious silos for stored grain
Date: 14 Aug 2012
As more growers look to increase on farm storage options for grain, the Grains Research and Development Corporation is aiming to improve the practice.
It is partly through the GRDC’s efforts that Australia now has a national standard for sealable silos, with the grains body warning people against buying a silo without it.
Grain storage specialist Peter Botta says those considering buying a new silo should know about the standard.
“While a lot of my extension work for the GRDC is holding workshops with growers to talk about pressure testing and hygiene, I also work with silo manufacturers.
“One outcome of this work is that we now have an Australian Standard (AS2628) for gas-tight sealable silos. This means a benchmark is now in place that buyers can refer to when buying new silos.”
Mr Botta says the reasons for ensuring grain storage silos are gas tight are manifold.
“A gas-tight sealed storage system allows growers to store grain for long periods confident that quality can be maintained, and insects fumigated if necessary.
“When using fumigation gases, the area being fumigated must be able to hold a concentration of gas for a length of time. In unsealed structures these requirements are not met, even if the dose rate is increased,” Mr Botta said.
“At best adult insects may be killed, but the pupae or eggs will most likely survive. These will continue to develop into adults to reinfest the grain, and if left unchecked can do a lot of damage.”
Mr Botta warns that although the Australian Standard is important to ensure quality in purchasing a new silo, even new silos should be pressure tested.
“A sealed silo should be pressure tested before use every time you plan to use it for storage, even if it’s the first time, to ensure it is suitably sealed.
“Growers should also pressure test the silo once it is filled with grain. Grain puts extra pressure on various parts of the silo including the bottom outlet plate which also must maintain its seal under load.”
It is recommended that all storages are fitted with aeration fans, including sealable silos. Mr Botta says it is easier to conduct pressure testing, and after fumigation the silo can be vented of gas in one day rather than five days. If no aeration is fitted to a sealable silo, install an air valve to pressurise the silo with an air compressor.
Remember you need a fair ‘volume’ of air going into a silo, not high pressure, to conduct a pressure test. For larger silos install a male PVC fitting to connect to a venturi gun that fits on the end of the air line.
Growers should ensure aeration fans are not left running into a sealed silo for more than 10 – 15 seconds as this can cause damage. Take extra care when placing seal covers over the intake of aeration fans.
Check oil levels before pressurising the silo to ensure oil levels are equal of both sides of the gauge and are at the middle indicator mark.
Once you pressurise the silo, Mr Botta says you should time the half-life.
“If oil levels are bubbling or further than 25mm apart, wait until the oil stops bubbling and is 25mm apart. The time taken to drop from 25mm to 12mm apart should be no less than 5 minutes on a new silo. For older silos, full of grain it should be 3 minutes.
“If the half - life is less than 5 minutes for new or 3 for older silos there is a leak. Find them by pressurising again and spraying soapy water from a spray bottle around seals.”
In terms of placement of silos, Mr Botta recommends following your manufacturers recommendations. In general, ensure silos are placed on cement slabs to assist in maintaining hygiene.
“If you are considering buying a new silo I would also seriously recommend you invest in an aeration cooling system,” he said.
“Aeration is the process of passing cool air through grain to reduce its temperature to a level where insect development, mould growth and moisture levels are dramatically reduced. As grain is cooled, insect development slows down and is negligible at temperatures below 15°C.
“Aeration systems can be used for either drying grain, cooling grain and for maintaining grain quality when stored over a longer time frame. By controlling grain temperature you control your stored grain so much more. It really is a necessity.
“By investing in quality storage equipment, and managing your system as well as you manage the crop in the paddock, growers can give themselves the flexibility and control they need.”
For more information about aeration cooling, head to YouTube to watch grain storage specialist Philip Burrill tell you all you need to know about getting the most out of it. Head to www.youtube.com/theGRDC
For information about grain storage workshops, contact Philip Burrill – 0427 696 500, Peter Botta 0417 501 890, Chris Warrick 0427 247 476
ENDSPHOTO CAPTION: Grain Storage expert Peter Botta
PHOTO CAPTION: Look for the Australian Standard when buying a new silo
Contact: Ellen McNamara
Cox Inall Communications
02 8204 3820; 0429 897 129
Region National, North, South, West