GRDC grain storage extension team member Ben White says empty pressure relief valves mean that silos will not retain fumigants. Photo: GRDC
What is the most common cause of on-farm silo seal failures in Western Australia?
According to Grains Research and Development Corporation (GRDC) grain storage extension team member Ben White, who has tested hundreds of silos across the State, it is empty silo pressure relief valves.
Mr White says a gas-tight silo is essential to maintain the fumigant gas concentrations required to kill stored grain insects at all life stages.
“If a silo is not gas-tight, the fumigation may appear successful when the adults die but the surviving eggs and pupae will continue to develop and reinfest the grain,” he said.
Mr White said that ahead of harvest, growers needed to ensure that silo pressure relief valves were filled to the correct level with light hydraulic oil to maintain their seal.
“A sufficiently full valve allows a controlled volume of air exchange in and out of the silo without excessively diluting fumigant levels,” he said.
“Without oil in the valve, the silo will not retain fumigants such as phosphine and fumigation will not disinfest grain.
“If the silo doesn’t have an oil valve, it is safe to assume it does not seal and should not be fumigated.”
Mr White said that once a silo pressure relief valve was filled with oil, growers should check that the silo seal exceeds a three-minute half-life pressure test. For new silos, half-life pressure tests should exceed five minutes.
“A pressure test is a measure of how well a silo will contain fumigation gas,” he said.
“Pressure testing silos needs to be part of the annual maintenance and it is much easier to replace seals and carry repairs out when silos are empty.
“However, a silo also needs to be pressure tested when full, before fumigating grain.
“This is especially important for silos with slide plate outlets that have been tested when empty – retest when full to make sure the pressure of the grain doesn’t compromise the seal.”
Mr White said that if growers were unsure how to do a pressure test, they could contact him on 1800 WEEVIL (1800 933 845)
More information about grain storage and pressure testing sealable silos is available by following this link.
1800 WEEVIL (1800 933 845)
Natalie Lee, Cox Inall Communications
08 9864 2034, 0427 189 827
GRDC Project Code