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Friday July 2 2021

How to Clean a Silo – Systems, Methods & Equipment

Silo cleaning and why it is important

Ensuring that your silos are clean is the key to making sure they are functioning correctly. A build up of debris over time can lead to clogging or a complete blockage in a silo, preventing the flow of material inside, be it cement, oil, grain, flour, chemicals or any other powdered, granulated or liquid product. This can delay production for weeks while the silo is evacuated, cleaned out, and refilled, and can lead to a considerable waste of product. Of course, it adds unnecessary cost to a job too, not to mention stress and potential penalties if production is stopped.

Silos need to be cleaned a minimum of once a year, but every six months is preferable. This is particularly the case if they are being used to store human foodstuff or animal feeds as it ensures mould doesn’t build up to unacceptable levels, and that the contents are kept as fresh and palatable as possible.

There are a number of ways of cleaning a silo and a host of tools available to carry that out, all of which we’ll cover in this article. However, there is another incredibly important aspect to consider – so important we’ve decided to address it first. And that is health & safety. Cleaning a silo can be a very dangerous job, and it is vital that those who carry it out are as safe and protected as they can be.

Health & Safety

The silo cleaning methods we use don’t require anyone to enter the silo, meaning they are relatively straight forward operations from the health & safety point of view.

We employ these methods because entering a silo can be extremely dangerous for workers and should be avoided if at all possible.

There are a number of potential hazards inside any silo such as the potential for falls or impacts with the inside walls of the silo, lack of oxygen, immersion and even the risk of drowning in the materials stored in the silo if liquid or finely milled products like sugar or flour.

The Occupational Safety and Health Administration (OSHA) define silos as a confined space which means any workers entering one must follow the standard procedures for an enclosed hazardous area.

This includes carrying out a risk assessment of the work and putting a plan in place before it commences. Such a plan would include aspects such as:

  • If a confined space has noxious fumes, you should consider how these can be ventilated or removed.
  • If there is a risk of liquids or gases flooding in, you should establish whether the valves can be locked shut.
  • If someone is going into a confined space and there is not enough oxygen to breathe properly, you must provide breathing apparatus or ventilate the space to increase oxygen levels before entering.

Such a plan would also need to include contingency planning around what to do in case of an emergency, such as a fall inside the silo or what to do if a worker is overcome by fumes. It is not enough just to rely on the emergency services, as not having a comprehensive plan in place could leave the silo owner liable.

Also, specialist equipment must be provided such as respirators, the right tools for cleaning the silo, and of course, all the necessary PPE.

Thankfully, however, the risks of entering a silo can be completed avoided with our cleaning methods, which can be applied, giving your silo a thorough clean, with operatives remaining outside.

This is the safest and most responsible approach to silo cleaning, and it doesn’t compromise the quality of the end result.

Silo Cleaning Methods

How you clean a silo often depends on what it is being used to store and which part of the silo you want to clean. That said, the main methods are vacuuming or using a silo whip.


Vacuuming is generally the first step employed to clean a silo used to store powdered, granular or liquid products. It is done either via a large, truck-mounted vacuum that is fed into the silo, or, in more modern silos, a vacuum can be built into the system design.

One of the major advantages of vacuuming is that it doesn’t require anyone to enter the silo to work, therefore it minimises health & safety issues surrounding the clean.

However, it is also restricted in what it can achieve. Vacuums are fantastic for removing loose powder or granulates that have collected in a silo but are less effective at removing ratholes – materials that have bonded to the internal silo walls.

Silo whip

A whip is used to remove material build up or blockages that are impacting on silo performance. Either pneumatically or hydraulically operated, a whip is a relatively portable piece of equipment that literally whips dry material loose with a boom arm, enabling the free, continuous process streams.

Whips can be inserted into a silo remotely and from the top, so like vacuuming, they don’t require operatives to work inside the silo. They eliminate the build up of dry matter such as grain, flour, salt, sugar, coal, ores and cement powder, recovering lost capacity and enabling maximum flow rates.

Material loosened by the whip simply falls to the bottom of the silo and can be removed in a conventional way. Whips are designed not to damage the interior of the silo, meaning they are an effective solution from both a health & safety and silo maintenance point of view.

Silo cleaning tools

Cleaning a silo without the proper tools can result in serious consequences such as damage to the silo wall and sparks caused during scraping by metal-on-metal contact, or by the build-up of an electrostatic charge, either of which could cause an explosion.

Therefore, it is vital to have the proper tools for the job as otherwise, serious accidents or incidents might occur.

Cleaning heads

When using a silo whip or any mechanised tool inside a silo, it is vital to use cleaning heads and whipsets that do not create static electricity.

Many storage vessels contain combustible product, gasses, or suspended dust particles that can ignite or explode if a spark were to be produced during cleanout operations, so removing the risk of this happening is paramount.

Products like plastic knuckles on whips or brass whip chains will ensure no electrostatic sparks are generated in the cleaning process, mitigating the risk of explosions.

Considerations by common material type

Although the general methods of silo cleaning are the same regardless of what is being stored, there are some specific issues relating to the different materials to look out for.

Cement silo cleaning methods

Given its purpose, it is no surprise that cement can bind to the inside of the silo walls – particularly in the presence of water – reducing both the live capacity of the bins and the material flow.

The best tool for cleaning a dry mortar silo is a pneumatic whip as this should generate enough force to dislodge the cement, while at the same time not damaging the silo.

Many experts recommend cleaning from the bottom of the silo upwards, as this destroys the underneath of any build-ups, causing them to collapse.

It is incredibly important to ensure the loosened materials can leave the silo without causing any blockages, so always make sure the takeaway mechanism is clear and fully operational before you start the clean.

Sugar silo cleaning

Like cement, sugar can build up on the inside walls of a silo, reducing the live capacity of the bins. Again, like cement, this can be particularly problematic if moisture has got into the silo.

That said, sugar that doesn’t get moist is often considered self-cleaning and build ups are relatively rare, meaning this is less of a problem than with other materials.

Dry sugar that does build up can easily be removed by a vacuum and if it is moist and needs and has set, a whip should soon shift it.

Flour silo cleaning

The demand for flour from the baking industry is huge and this can mean flour silos are running 24 hours a day, 365 days a year. Over time, product residue builds up which, once it reaches a certain point, fall off as lumps of flour and block the system. This can be very costly for food businesses.

The quality of the flour will have a significant bearing on the extent of the problem, with ‘strong’ flour being more adhesive and harder to remove. Manual cleaning is possible but is physically and mentally demanding for workers as often the flour has hardened and must be scraped off, while wearing extensive breathing apparatus to protect them from inhaling dust.

Remote mechanical cleaning can also be employed in flour silos, which is the preferred option from a health & safety point of view.

Due to their use in the food industry, hygiene is another major consideration when cleaning flour silos as the operatives must be incredibly careful not to introduce any contaminants into the storage equipment.

Grain silo cleaning methods

Grain is far less adhesive than cement, sugar, and flour, and as a result, cleaning grain silos is a much easier process than those used to store other materials.

The most common way to clean a grain silo is vacuuming with a disab.

To find out more about our silo cleaning services, get in touch.