Risks And Hazards Associated With Fans

Fast-spinning impeller blades are the obvious risk with any fan. But there are more – including moving belts, electrical hazards, noise, manual handling, dust/debris/water ingress, and chemical attacks.

Let’s examine those risks one by one – and what can be done to mitigate them, ensuring the safety of workers and the reliable operation of the fan.


Screenshot of the ACI fan selector tool


Rotating Impellers And Other High-Risk Components

It’s not just the impeller blades that can create a safety hazard: drive systems and rotating shafts can pose a risk of injury if not properly guarded or if maintenance protocols are not followed. There are four important steps to minimising risk:
1. Guarding:

One of the primary measures to mitigate the risks associated with rotating components is to install appropriate guards that prevent accidental contact with moving parts. Guards should be designed, installed and maintained in accordance with the relevant safety standards to ensure effective protection.

2. Risk Assessment:

Conducting a thorough risk assessment is essential to identify potential hazards associated with rotating blades, belts and shafts. This assessment helps in determining the necessary control measures and safeguards required. It is important to involve qualified personnel with expertise in fan safety engineering during the risk assessment process.

3. Safe Design and Maintenance.

Ensuring proper design and maintenance of fans is crucial. Fans should be designed to minimise operator exposure to rotating components, reducing the risk of accidental contact. Regular inspection and maintenance procedures must be followed to ensure the rotating parts are in good working condition.

4. Training and Awareness.

Operators and maintenance personnel should be provided with the correct training to raise awareness about the risks associated with rotating components. Personnel should be educated about safe work practices, including lock out/tag out (LOTO) procedures, proper use of personal protective equipment, and the importance of following established safety protocols.

In most cases, the prime area of concern is the impeller but some fans – such as the ACI EP10A – can be belt driven, so guards are an important safety consideration. Importantly, the EP10A benefits from an advanced design that allows the fan to be driven at a lower belt tension. This reduces the load on moving parts, prolonging their longevity and improving reliability.

Why BS EN ISO 13857:2019 Is So Important

BS EN ISO 13857:2019 is a British standard that provides guidelines for evaluating and minimising the risk of crushing or shearing hazards related to machinery. Although this standard is not specific to fans, it is applicable to all types of machinery – including those with rotating blades, belts and shafts.

This 32-page standard emphasises the importance of safeguarding measures, such as guarding, interlocking systems, and control devices to prevent access to hazardous areas. It provides guidance on determining the minimum distances required to ensure safe access to moving parts (considering factors such as reach, height, and speed).

BS EN ISO 13857:2019 serves as a valuable reference for engineers by providing a systematic approach to risk assessment and control measures. It helps engineers to evaluate the adequacy of existing safeguards and implement additional measures to reduce the risk of accidents and injuries associated with rotating blades, belts and shafts.

Adhering to this standard demonstrates a commitment to safety. It is essential to consult the standard directly for specific details and to apply its recommendations (in conjunction with other relevant industry standards and local regulations).

ISO 13857 Manual Front Page

Mitigating Safety Hazards Posed By Electricity

Any electrical device can pose a threat if the voltage is high enough. When dealing with electrical equipment, the voltage and amperage at which humans are at risk can vary depending on various factors, including:
  • the path of the current flow
  • duration of exposure
  • individual circumstances, such as the age and health of the person concerned.

However, certain general guidelines are commonly followed for electrical safety:

  • Voltages above 50 volts AC or 120 volts DC are generally considered hazardous. This is because they can penetrate the human body’s resistance (typically around 1,000 ohms for dry skin) and potentially cause electric shock. However, even lower voltages can be hazardous under certain conditions, such as contact with wet or conductive surfaces.


  • Amperage (current) also plays a role in determining the severity of electric shock. Currents as low as 1 milliamp (mA) can be felt, while currents above 10 mA can cause muscle contractions and prevent an individual from releasing the source of electric shock. Currents above 100 mA can induce ventricular fibrillation, a potentially life-threatening heart rhythm disturbance. However, the severity of the shock also depends on factors such as the duration of exposure and the path of current through the body.
To ensure electrical safety, it is crucial to follow the Electricity at Work Regulations, the Wiring Regulations and other relevant industry standards.

Employers should provide proper training, use appropriate personal protective equipment (PPE), implement safe work practices, and consult with qualified professionals when dealing with electrical equipment or systems.

Protecting Workers From The Effects Of Noise

Fans and air knives supplied by ACI are designed to operate at lower noise levels. Our premium LNL series features enclosures that keep noise levels well below the 85 dB(A) threshold.

Here are several reasons why this threshold is significant:

  • Prolonged exposure to high noise levels can lead to noise-induced hearing loss (NIHL), a permanent and irreversible condition. Studies have shown that regular exposure to noise levels above 85 dBA can result in hearing damage over time. By setting the upper exposure action value (UEAV) at 85 dBA, the regulations aim to prevent or reduce the risk of occupational NIHL.
  • There is a recognised dose-response relationship between noise exposure and the likelihood of developing hearing damage: as noise exposure increases, so does the risk of hearing damage. Importantly, 85 dBA is considered a critical threshold, after which the risk of harm rises significantly.
  • International Consensus – the 85 dBA threshold for action and control of noise exposure is widely adopted and supported by international standards organisations, including the International Organization for Standardization (ISO) and the American Conference of Governmental Industrial Hygienists (ACGIH). This consistency allows for harmonisation and a common approach to protecting workers’ hearing health worldwide.
  • Practical Considerations – setting the UEAV at 85 dBA provides a practical balance between protecting workers’ hearing and allowing for the feasibility of implementing control measures. It is recognised as an achievable level that allows employers to implement engineering controls, administrative measures and the use of personal protective equipment (PPE) effectively to reduce noise exposure.

However, it is important to note that the 85 dBA threshold does not imply safety below that level. Continuous efforts are made to minimise noise exposure and to promote the use of engineering controls – such as noise isolation, damping and source reduction – to further protect workers’ hearing health.

In the UK, the Control of Noise at Work Regulations 2005 (CNWR) do not define a maximum permissible noise level in decibels. Instead, they focus on the exposure of workers to noise and the employer’s responsibility to mitigate and reduce that exposure through risk assessments, controls and monitoring.

If noise exposure exceeds the UEAV, employers are required to:

  • assess and manage noise risks in the workplace
  • provide information and training to employees
  • undertake health surveillance.
Opened enclosure designed to reduce noise level
Closed in

Third-Octave Tests For Noise

ACI is able to perform Third Octave noise tests to measure and analyse sound across the frequency spectrum. These tests divide the audible frequency range into smaller third-octave bands. Testing provides detailed information about the sound characteristics and distribution of noise across different frequencies.

In a third-octave noise test, the audible frequency range (usually from 20 Hz to 20,000 Hz) is divided into one-third octave bands. Each band is centred on a specific frequency and has a bandwidth that is one-third of an octave wide. The centre frequencies of these bands are spaced logarithmically, allowing for a more detailed analysis of noise across the frequency spectrum.

The test is typically conducted using specialised sound level meters or analysers capable of measuring sound pressure levels (SPL) in each third-octave band. The sound level meter captures sound using a microphone and then performs frequency analysis by measuring and recording the SPL in each band.

The results of a third-octave noise test are often presented in the form of a noise spectrum table or graph. The information is valuable in several ways:

  • Identifying noise sources – by analysing the noise spectrum, it becomes easier to identify specific frequencies or frequency ranges where noise is more prominent. This helps us to pinpoint the sources of noise within a fan.
  • Assessing noise control measures – third-octave noise testing can help to evaluate the effectiveness of noise control measures by comparing the noise spectrum before and after the implementation of mitigation strategies. It helps to determine the success of noise reduction efforts across different frequency bands.
  • Compliance and standards – third-octave noise testing allows for accurate measurement and assessment of noise levels in accordance with specific regulations, standards or guidelines. It provides essential data for noise impact assessments and helps to ensure compliance with noise limits.
Table showing results of a third octave test for a fan.

Temperature Rise Tests

Temperature rise tests are an important safety measure in fan engineering. They are conducted to evaluate the performance and reliability of fans under operating conditions – notably their ability to handle thermal stress.

We need to verify that a fan can withstand prolonged operation without excessive temperature rises that could lead to motor or bearing failures. Testing also helps identify any potential issues related to fan design, motor performance or thermal management.

We test newly manufactured fans to ensure they can operate within acceptable temperature limits and will not overheat.

In a temperature rise test, we measure the motor’s electrical resistance through the windings, run it for a minimum three hours, then measure the resistance again. This enables us to accurately calculate the rise in heat in the motor windings.

The fan’s inlets and discharges are subjected to the conditions relevant to the type of testing required, whether it be for a customer or in-house testing for a new development.

Most fans from ACI are fitted with motors with insulation class F. This is one of the several insulation classes defined by international standards to indicate the maximum temperature that the insulation can withstand.

In the context of electrical motors, insulation class F refers to an insulation system that can operate reliably at temperatures up to 155°C. This means that the motor is designed to handle higher maximum temperatures, compared with lower insulation classes such as A (105°C) and B (130°C).

Insulation class F is commonly used in applications where motors may experience high temperatures or have to operate under heavy loads for extended periods. The increased temperature rating of class F insulation allows for better thermal performance and improved reliability.

It’s important to note that the insulation class is just one factor to consider when selecting a motor or electrical device for a specific application. Other factors, such as environmental conditions, duty cycle and cooling methods, should also be considered to ensure the proper operation and longevity of the equipment.



Equipment to test fan temperature

Protecting Your Fans From Dust And Water Ingress

Most fans supplied by ACI are rated either IP 54 or IP 55 for ingress protection. Some may be rated IP 65 or IP 66.

IP (Ingress Protection) ratings are a standardised classification system used to indicate the level of protection provided by an enclosure against the intrusion of solid objects, dust and water. The rating is expressed as IP followed by two digits:

In the context of the aforementioned IP 54, IP 55, IP 65 and IP 66, the first digit indicates protection against dust:

  • 5: Limited protection against dust ingress but not entirely dust-tight.
  • 6: Completely dust tight, providing full protection against dust.

The second digit indicates protection against liquids:

  • 4: Protection against splashing water from any direction.
  • 5: Protection against low-pressure water jets from any direction.
  • 6: Protection against powerful water jets or heavy seas.

Chemical Attacks On Fans

Mild steel and aluminium are the most common materials used in ACI’s fan construction due to their cost-effectiveness and mechanical properties. However, mild steel is susceptible to corrosion and degradation when exposed to aggressive chemical environments. Here are some of the risks associated with chemical attacks on fans containing mild steel:
  • Corrosion – chemicals can corrode mild steel, leading to the deterioration of fan components. Corrosion weakens the structural integrity of the fan, potentially causing leaks, reduced efficiency, and ultimately, equipment failure.
  • Reduced lifespan – chemical attacks accelerate the degradation process of mild steel fans, shortening their working life. Corrosion-related damage can compromise the fan’s performance and efficiency over time, leading to increased maintenance and replacement costs.
  • Impaired performance – corrosion and chemical attacks can affect the fan’s aerodynamic properties, such as blade shape and surface roughness. This can result in reduced airflow, decreased efficiency and higher energy consumption.
  • Contamination – chemical attacks can cause the release of particles or corrosive substances into the airflow. These contaminants can be hazardous to health or cause further damage to downstream equipment or processes.
  • Safety hazards – in extreme cases, chemical attacks on mild steel fans can lead to structural failure or catastrophic events, posing safety hazards to personnel and surrounding equipment. Fan components may fracture or break under the influence of chemical corrosion, potentially causing accidents or injuries.
Fan with stainless steel casing
There are various ways to mitigate the risks associated with chemical attacks on mild steel:

  • Material selection – opt for alternative fan materials that are more resistant to chemical attacks, such as stainless steel and fiberglass-reinforced plastics.
  • Protective coatings – apply suitable coatings or linings to the mild steel fan surfaces to create a barrier against chemical exposure and corrosion.
  • Chemical compatibility – ensure the fan materials and coatings are compatible with the specific chemicals present in the operating environment. Consult chemical resistance charts and seek expert advice.
  • Environmental controls – implement measures to control and minimise chemical exposure. Possible measures include proper ventilation, containment systems or chemical neutralisation procedures.
  • Regular maintenance – implement a proactive maintenance program to inspect, clean and repair fans regularly. This includes monitoring for signs of corrosion, replacing damaged components and applying protective coatings as needed.

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