It is very important to keep silos clean. If they are not cleaned correctly they could overflow, crack, or the material inside the silo could become contaminated. These large silos, which can be formed as cylinders or pits are used to store material such as food (grain, dog food, wheat, rice) and other material such as cement. It is especially important that the food doesn’t become contaminated, but if the silo cracks and there is cement in them, it can be dangerous.
The size of silos and the fact that inside them is masses and masses of material means that cleaning them isn’t always straight forward, and it needs to be managed and monitored properly.
Food-material silos need to be cleaned regularly as insects and other contaminating substances can enter the silo through cracks. Mould could also form when the silo is left untouched.
All silos need to be emptied before cleaning. This is the most practical solution and means that material won’t be wasted or contaminated by products.
The most common method of silo cleaning is manually. A full risk and safety assessment needs to be taken beforehand, and should only be done by a professional silo cleaner. There is usually a hatch at the top of the silo where the worker enters, which is much more safe than entering the silo from the bottom. It is therefore more safe and more effective to clean the silo from the top down. The cleaner will have a platform or cage they stand in which will be lowered into the silo. If one is manually cleaning the silo, a dry method is usually implicated. First, it is beneficial to vacuum the surfaces to make sure most of the excess powder and material is gone. Then one usually dry scrapes or brushes the walls of the silo.
If there is mould present in the silo, it is possible to wet clean the silo. This can be done by low-pressure cleaning, medium- pressure cleaning and high-pressure cleaning. This is when a chemical cleaning agent it used to clean the silo and the volume flow is adjusted. If this method is used it is important to blow dry the silo immediately afterwards.
It is also possible to not clean the silo manually, but use equipment. An example of this is rotating cleaners. This is used for larger storage tanks such as fermentation tanks. These are designed to work under low pressure. It is like a rotating set of “flails” that whips against the material in the silo. This will be lowered into the silo from an access point on a pivoting arm. It usually has a cleaning radius of 56 feet. The rotating cleaners are usually air-powered by a compressor.
Static cleaners can also be used to clean out storage tanks. These are also designed to work under low pressure. A spray head sprays cleaning agent onto the silo walls and the cleaning is performed by rinsing the agent off the walls. Because of the cleaning agent it works to cut down the cleaning time, as the cleaning agent breaks down the matter.
Orbital cleaners is a concentrated jet to remove the substance from inside the tank. These work with low, medium or high pressure.