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Industrial Fans & Noise

The important factor to consider is the fan’s blade pass frequency, which is a pure tone produced when the blades of the fan wheel (impeller) rotate past the housing cut-off sheet in centrifugal fans, or the turning vanes, in axial fans. The blade pass frequency is calculated by multiplying the number of blades times the rotating speed in revolutions per minute. If this frequency matches the natural frequency of the ductwork, it can excite the ductwork, which can cause it to resonate, thereby increasing the noise level. Because of this possible increase in sound, and because certain pure tones are irritating to people, the sound output of the blade pass frequency should be investigated when sound reduction is desired. The next factor to consider is the fan design. Generally a fan operating at peak mechanical efficiency will produce less noise, because high efficiencies result from minimal air turbulence within the fan.

The sound generated by some fans can be a potential hazard to personnel in close proximity to the fan, and the sound can be transmitted, via the ductwork connected to the fan, to all areas serviced by the fan. Because of these concerns, fan manufacturers publish sound ratings for their products to serve as a guide for selecting fans to meet sound specifications, and to assist acoustical consultants in predicting the total noise levels in specific environments. This article provides basic information to help understand fan sound ratings and how to apply them. Like any mechanical device, fans generate sound, which emanates naturally from the turbulence of moving air, the mechanics of moving parts of the fan, and from vibration.

Air turbulence within the fan increases the sound coming from the air movement. The noise resulting from air turbulence is a major factor in the sound levels of a fan in a specific application. Further, duct work can transmit this turbulent noise to all areas serviced by the fan. Factors contributing to air turbulence include the resistance to flow, flow separation along fan surfaces, and shock related to abrupt changes in the direction of airflow, pressure, or velocity. A lower noise level can be achieved by reducing air turbulence. This can be done by considering several factors related to air movement when selecting fans.

Industrial Centrifugal Fans Design

There are four basic centrifugal fan wheel designs – forward curved, backwardly inclined, radial, and radial tip – and a variety of axial flow wheel designs. Each wheel design has unique sound characteristics due to the way they handle air, and the efficiencies they can achieve. Fan speed does not always determine which fan will be quieter. For example, centrifugal fans have higher amplitudes at lower frequencies, while axial fans exhibit higher amplitudes at the higher frequencies. The amplitude of the blade pass frequency on an axial fan is higher and more pronounced than on backwardly-inclined fans, and commonly will have amplitude peaks at multiples of this frequency.

Backward Inclined Fans

Of the four centrifugal designs, the backwardly inclined fans are the most efficient, and therefore, the quietest. Those with airfoil-shaped blades offer the highest efficiencies, for clean air environments, while those with single-thickness blades can be used in applications where light dust or moisture is present, although the efficiencies are somewhat lower.

Axial & Vaneaxial Industrial Fans

Certain types of axial fans offer the next highest efficiencies. An excellent example is the Vaneaxial fan that uses airfoil shaped blades in an in-line flow design. This fan is used to handle high volumes of clean air at low pressures, which is a typical ventilation application.

Radial Blade Fans

Radial fans are typically low efficiency, open designs for special purpose applications, such as bulk material handling, or exhausting / supplying lower volumes of air at higher pressures. A radial fan will be much louder than a backwardly-inclined fan operating under the same volume and pressure conditions.

Radial Tip Fans

Radial Tip fans, commonly used to handle larger volumes of air that contains particles or material, exhibit sound characteristics similar to the radial fans. The sound spectra of radial and radial tip fans contain amplitude spikes at various frequencies, and a noticeable spike at the blade pass frequency.

Forward Curve Fans

The forward-curved fan design operates at speeds that are much slower than the other fan types, which results in lower noise levels from mechanical operation and vibration. However, because of its modest efficiencies, a forward curved fan may be noisier than a backwardly-inclined fan when operating at comparable volume and pressure. The sound spectrum of the forward-curved fan shows a slower rate of reduction in amplitudes than the other centrifugal types, and because of the large number of blades, the blade pass frequency occurs much later in the spectrum and is not predominant.

Industrial Fan Components

The moving components of the fan – the motor, bearings, and drive – produce sound. This too can be transmitted through the system via the fan structure or shaft, or when these components are in the airstream. Motor sound will vary with speed, enclosure, electrical characteristics, and even the manufacturer. Antifriction bearings can be used to reduce bearing noise, and proper drive selection will reduce the likelihood of belt hop, or slap. Of course, proper maintenance must be employed to keep the moving parts running smoothly, and quietly.

Excessive vibration can significantly add to the overall noise level of an installation. This will occur if the fan or any of its components are not adequately balanced, if the fan is installed on an insufficient foundation, or if the fan is not properly isolated from other system components. For example, it is not uncommon for the fan’s support structure or ductwork to have a natural frequency at the fan’s operating speed or blade pass frequency, either of which can cause the system to resonate at that frequency, increasing the sound levels, and the possibility of damaging the installation. These risks can be eliminated by changing the speed of the fan, installing appropriate isolation, and / or detuning of the fan or affected system components.

dBA is a useful measurement for evaluating the overall noise level at a particular location, but this measurement takes into account all of the sound sources affecting that particular location, which include the sounds from all equipment in the area, natural sounds of the environment, and from other environmental factors. Some of these factors are the current physical properties of the air such as temperature, humidity, and pressure, whether the location is outside or inside, the size and material of the room. All of these affect the sound pressure experienced by the listener, and recorded by the sound level meter.

Published fan sound power ratings and corrections only reflect noise created by air turbulence within the fan. Because of the infinite variables, mechanical noise and vibration noise are impossible to accurately predict, and are not included in the rating.

Additional information can be found at the Northern Fan web site http://northernindustrialsupplycompany.com/products/ventilators.html

Oleg Cthetchel
Air Process Systems Engineer
nis@primus.ca
Northern Fan Co.
http://northernindustrialsupplycompany.com
http://northernindustrialsupplycompany.com/burlington/request6.html

Fans and Blowers Noise Levels

nis@primus.ca

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Industrial Fans Canada

People these days opt to use fans for their ventilation needs. A mechanical fan often has many uses around the house and inside buildings. This versatile appliance can serve as a cooling instrument especially during the summer and it can also be used during winter to push warm air down in order to heat a room.

Axial fans, centrifugal fans

In the industry, there are many types of fans such as axial fans, centrifugal fans, crossflow fans and bladeless fans. These types of fans have features, structures and benefits. Each one offers different processes and ways of balancing the temperature. Their usage also depends on the kind and size of the room that needs ventilation. This enables engineers to choose the right kind of ventilation that will coincide with the design they have in mind for their buildings.

Axial Fans

Axial fans are the typical household fans we see every day. This type of fan has three or more blades that rotate to allow air to pass through and circulate around a room. Axial fans are operated by electricity to balance the temperature and permit air to flow inside a room.

Damper Fan

A damper fan is a duct-like device used to neutralize temperature through ventilation ducts. There are many damper manufacturers who produce fire dampers that help prevent the spreading fires in buildings and houses. These fans are designed to close once subjected to heat and/or fire. Engineers and architects are incorporating fire dampers in their design to effectively reduce the damage that a fire can cause.

A dampers manufacturer makes sure that its products are safe for use by consumers. They make certain that their products materials are of the highest grade and quality so as not to risk the safety of the building where the fans will be used.

Centrifugal Fan

A centrifugal fan manufacturer sells fans that are quite different from the other types of fans. This type of fan is composed of different instruments which control the fans speed. It is a typically larger mechanism compared to other fans to accommodate bigger structures like office buildings and factories. All of these fans aim to maintain the convenience of the people regarding temperature balance.

Some Of The Industries That Heavily Require Ventilation Are:

•Pharmaceutical Industry
•Biological Industry
•Chemical Industry
•Mining Sector
•Physical Research Industry
•Processing units

For additional information please refer to http://www.industrialblowerfan.com

Susanna Terlitskaia
Industrial Ventilating Engineer
Industrial Blower Fans Company
nis@primus.ca
http://www.industrialblowerfan.com/axial-fans-man-coolers.html
http://www.industrialblowerfan.com/scrubbers-dust-collectors.html

Fans and Dampers

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nis@primus.ca

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Industrial Ventilators – High Temperature

One of the most critical components of the fan are the bearings. So naturally if the bearings are kept out of the hot airstream they are less susceptible to the effects of the high temperature, and therefore the air temperature can be higher than the limiting temperature of the bearings. Inline fans inherently have drive components in the airstream. In such cases, the unit can sometimes be designed so that cooler outside air is drawn over the drive components, providing some additional cooling. Incorporating this type of external cooling is one of the main reasons Northern Fan medium pressure tube axial inline fan (TBI) can be used for high temperature exhaust applications. There are, however, some arrangements that donÕt allow for the incorporation and benefits of external cooling. For instance, fans in arrangement 3 have the wheel suspended in-between the two bearings. Consequently, one or both of the bearings will always be located in the air stream. Similarly, direct drive fans are limited by the maximum operating temperature of the motor, since the motor is located directly in the hot air stream. That is why most often high temperature exhaust fans are required to be belt driven units; typically the motor is the temperature-limiting component of the unit when it is installed in the airstream. Other than the installation location of the bearing within the fan assembly, other critical points to consider include the type of lubrication in the bearing, as well as the construction of the bearing itself. There is a seemingly endless list of lubricants available for most any application, but the appropriate lubricant can add considerable life to bearing operation. In addition, high temperature bearings can be constructed with inherent construction modifications, such as a larger grease cavity to hold more lubricant.

Industrial Fan Design

Another common variation to the standard fan design is the addition of insulation. The bearing mounting plate, bearing cover and belt tube are the most likely components to be insulated for a high temperature application. Northern Fan automatically includes insulation for these components on all fans specified with either HT Option III or HT Option IV.

Exhaust Fans

It is important to understand that emergency smoke exhaust fans are designed to operate effectively for the temperature and time limits stated as long as the power supply to the fan is not terminated. Since they are not designed to sustain higher temperatures for continuous use, exposure to the extreme high temperatures caused by a fire likely would destroy some or all parts of the fan once the time design limit has elapsed, rendering it incapable of future operation.

High Temperature Fans

Fans that are built for continuous high temperature ventilation have many of the same construction features and options as those built for emergency smoke exhaust. For example, both are typically constructed of higher temperature ferrous materials, have high temperature bearings, have the motor and drive installed either out of the airstream or with some type of additional cooling capabilities, and incorporate some heat shielding or insulation. There are, however, some distinct differences between the fan designs for the two application categories. One of the most common applications for which continuous duty high temperature exhaust fans are specified is commercial kitchen ventilation.

Fans that are specified for continuous operation at higher temperatures need to be carefully selected taking into account air density corrections. Although a fan will move the same amount of air at two different temperatures, the static pressure and horsepower requirements can change drastically as the density of the air varies with changing temperatures. For example, if a fan moves 3,000 CFM at 70 F it will also move 3,000 cfm at 500 F. However, since the hotter air weighs much less than the 70 F air, the fan will require less brake horsepower and will create less static pressure.

There are also some accessories and construction options that are incorporated into high temperature process fans to increase the limiting temperature. For example, a heat slinger can be installed on the shaft between the fan housing and the inboard bearing. A heat slinger is an aluminum disc that absorbs and dissipates some of the heat conducted along the shaft before it travels to the bearings. Many heat slingers incorporate fans that promote additional inboard bearing cooling because it circulates air with every rotation of the shaft.

Another common construction technique is the use of a heat gap. A heat gap is a physical gap between the bearing support structure and the hot fan housing. This separation slows the process of heat conduction to the bearings and drive components through the housing and support structure. An expansion bearing should be installed where the fan shaft is predicted to conduct enough heat that it could expand to a length greater than that of the structure to which it is secured. This allows for expansion of the shaft within the bearing due to the higher temperatures.

High temperature applications can be found in many different areas of the air movement and control industry. It is important to remember that one high temperature fan design is not suited to all applications.

Additional information can be found at the Northern Fan web site http://www.northernindustrialsupplycompany.com/products/heat_exchangers.html

Oleg Cthetchel
Canadian Air Systems Engineer
airknife@cogeco.ca
Northern Fan Co.
http://northernindustrialsupplycompany.com/products/industrialfan_blowers.html
http://northernindustrialsupplycompany.com/products/ventilators.html

High Temperature Ventilators Fans

airknife@cogeco.ca

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Industrial Fan Performance

Visual inspections of the ventilation system often reveal some easily rectified problems that can significantly impair performance. If the system has not been properly maintained, clogged filters or obstructed coils will reduce airflow. The greater the obstruction, the greater the loss in airflow. Any leaks in the ductwork will contribute to reduced performance, especially leaks around plenum bulkheads that can lead to recirculation of air. Worn flexible connectors are a common source of leaks and should be inspected regularly. If the damper linkage is out of adjustment, the damper may not be opening completely, thereby reducing performance. If inlet dampers are used, make sure they are installed so that the air is pre-spun in the same direction as wheel rotation. For all dampers, make sure there is sufficient clearance for the blades to open and close completely without hitting the ductwork or other system components. Last, for systems with either pneumatic or electric controls, make sure damper actuators are operating properly. Sharp changes in the direction of airflow at either the fan inlet or outlet will disrupt the flow through the fan and impair performance. If it is impossible to straighten the ductwork entering and leaving the fan, the use of inlet boxes and turning vanes can minimize performance losses.

Industrial processes and plant ventilation

Industrial processes and plant ventilation systems often need more air than originally designed. Increased production requirements, process changes, and facility renovations are a few of the major reasons. Additionally, the lack of adequate maintenance over time can negatively impact system airflows. This article discusses several procedures that can increase airflow. Often airflow can be increased by adhering to proper fan maintenance procedures as outlined in fan installation and maintenance literature.

Centrifugal Fans & Fan Speed

Fan speed can decrease by as much as 10% to 20% when belts are too loose, with a corresponding loss of airflow. A fan cannot perform as designed if the air flow surfaces are distorted by contaminants. Even in large fans, a sixteenth of an inch of build up can reduce performance. Centrifugal fans will move some air even when running backwards. While some types would use so much horsepower they would trip circuit breakers, other design s could run for years without being detected. Fan components may be out of position due to routine cleaning or painting or the wheel could have shifted during shipment. For backward inclined fans, the relation of wheel to inlet cone is very critical. Even a quarter of an inch can have a major impact. The fan’s installation and maintenance literature shows the proper positioning of the wheel to the inlet cone.

Low Airflow Problems

One of the easiest solutions to low airflow problems is speeding up the fan. While airflow is increased by speeding up the fan, so too are static pressure, noise, and power requirements. Therefore, while increasing the fan’s speed is an easy procedure with low first cost, the additional operating expense over time makes it the most costly solution. When increasing fan speed, it is necessary to check the maximum safe speed of the fan and make sure the motor is capable of the horsepower required to run the fan at the new speed. But never run a fan beyond its maximum safe speed.

Industrial Fans & Improving Airflow

On a first-cost basis, adding or replacing fan equipment is the most costly alternative. However, on a life-cycle-cost basis, considering operating and maintenance expense, it can be the least expensive, as compared to increasing the speed of an existing fan. Sometimes a second fan may be added, either in series or parallel with the original, although it may be more cost effective to simply upgrade the system with a new fan capable of the required airflow and pressure. Adding another fan in series will increase the airflow because of the additional pressure. The operating point of the new system moves further out/up the system curve. Where duct size is adequate to handle the desired amount of air but the existing fan doesn’t provide sufficient pressure, a second fan in series may be the best solution. However, make sure the ductwork can handle the increase in pressure. Adding another fan in parallel with the first will increase airflow due to the combined capacities. Because capacities are being combined instead of pressures, a greater increase in airflow will result for a given system. However, system pressures will also increase and caution is required to avoid the unstable operating area of the combined fan system.

When more air is required it is important to investigate the system on a step-by-step basis, considering the least expensive possibilities first. For existing systems that seem to have lost performance, fan and system maintenance is the place to start. Often, simply improving the efficiency of existing components will suffice. For systems that require greater airflow and / or pressure, increased fan speed is generally the first alternative. However, when large increases in performance are required, there may be no alternative but to purchase a larger fan.

For additional information please refer to http://www.northernindustrialsupplycompany.com/burlington/request5.html

Oleg Tchetchel
Industrial Ventilating Designer
airknife@cogeco.ca
Northern Fan Co.
http://www.northernindustrialsupplycompany.com/burlington/request7.html
http://www.northernindustrialsupplycompany.com/burlington/request2.html

How to Increase Fan Performances

airknife@cogeco.ca

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olegsystems

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Industrial Fans – Types

Different models of fans are available in the market in various unique designs, integrated with the latest technologies and low power consumption facilities. The variety of elegant fans includes integrated gear box and push button switch to suit any decor.Many stylish fans with double ball bearing are available in lots of colors which are integrated with dynamically balanced blade for maximum air delivery.The use of radial blower in the fans helps in moving air perpendicular to the blower axis and provides relatively low flow rates and high pressures.

Types of Blowers & Fans

The wide range of blowers and fans includes non-decorative Ceiling fans, wall mount fans, decorative ceiling fans, single centrifugal blowers, dual centrifugal blowers, radial wheel blowers, cast aluminum blowers, high pressure blowers, belt driven blowers, explosion proof and food safe blowers, high temperature oven circulating fans, industrial fans and also stainless steel and other alloy fans are available in the market. Finest quality, durability and enduring performances of these fans are catching more attention of the market these days. A wide range of axial flow fans is designed to provide efficient trouble free service & reduce the initial and operating cost to minimum. Apart from the fans there are various other products like air blowers, air scrubbers, axial fans, axial flow fans, centrifugal blowers, cyclone seperators, dust collecting equipment, dust collector, exhaust blowers, fan blowers, industrial blowers and many more.

Non-Decorative Ceiling Fans are integrated with the low power consumption facility with double ball bearing for maximum air delivery and available at very reasonable price. Non-Decorative Ceiling Fans are high speed fans, which are available with four blades to provide maximum air delivery and best for all small rooms. Non-Decorative Ceiling Fans has variety of designs and colors available at the best competitive prices. Non-Decorative Ceiling Fans consists of power saving technologies which make it more unique and high monopoly holder in the competitive market.

Wall Mount Fans are available in sleek and stylish look with less noise and delivers maximum air pressure. Wall Mount Fans are integrated with aluminium blade coated which increases its life and also gives an elegant look to your room. Wall Mount Fans are available in many colors like Blue, Red, Brown, Cherry and lots more.

Decorative Ceiling Fans are one of the most demanding ranges of fans in the market. The aluminium body with golden touch offers a unique look and suits any decor. These days, the latest technology of power saving in fans attracts the market and consumers as well.

For additional information please refer to http://www.industrialblowerfan.com/products.html

Susanna Terlitskaia
Industrial Ventilating Engineer
Industrial Blower Fans Company
nis@primus.ca
http://www.industrialblowerfan.com/feedback.html
http://www.industrialblowerfan.com/contact.html

Fan Types

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Industrial Exhaust Fans

Exhaust fans can be grouped into two general categories: emergency smoke evacuation and process ventilation. Generally speaking, emergency smoke evacuation fans may never be used, but they must be installed and be capable of exhausting high temperature air and smoke in the event of a fire. In contrast, high temperature process ventilation requires continuous duty exhaust of high temperature air, fumes or particulate. Both application types are uniquely different requiring special construction and system design considerations. In this article, we will examine both types of exhaust applications, looking first at the emergency smoke exhaust category. Since emergency smoke exhaust deals with lifesafety issues, there are governing bodies in place that identify and regulate specific design and performance standards. The administration and organization of the various governing bodies is subject to modification based on the needs of the industry. Currently, four such agencies are Industrial Risk Insurers (IRI), Southern Building Code Congress International, Inc (SBCCI), the National Fire Protection Association (NFPA), and Underwriters Laboratories, Inc. (UL). IRI insures properties all over the world based on an informational manual, which details the construction requirements that belt drive emergency heat and smoke exhausters must meet in order to be covered by IRI.

SBCCI is a not-for-profit organization of government officials from the United States and several foreign governments, which serves a strong leadership role in the delivery of model building codes. The purpose of the NFPA can be summarized into three main categories. First, NFPA promotes the science and improves the methods of fire protection and prevention, electrical safety, and other related safety goals. Secondly, it obtains and circulates information on these subjects. And thirdly, it secures the cooperation of its members and the public in establishing proper safeguards against loss of life and property. The fourth organization is Underwriters Laboratories, Inc.. UL is a non-profit, independent organization that maintains and operates laboratories for examination and testing of devices, systems and materials to determine their relation to life, casualty hazards and crime prevention. UL has three safety standards that apply to emergency smoke exhaust products. UL705 is concerned with the mechanical and electrical construction to insure safe operation. All electrical components (motor, wiring, switches, enclosures, etc.) must be ULlisted. UL793 is concerned with the lifting mechanism for the butterfly dampers and the fusible link. In order for a product to be listed in the UL Directory under ÒPower Ventilators for Smoke Control Systems,Ó it must meet the requirements of both UL705 and UL793. Additionally, UL must witness a full-scale test of a fan operating for the required time at the specified elevated and temperature.

High Temperature Exhaust Fans

So what makes one fan more capable of sustaining higher temperatures than another fan? Each model has a recommended maximum operating temperature based on the construction materials, drive components, and airflow characteristics. The limiting temperature is determined to be the highest temperature that any component of the fan assembly will reach during any operating cycle. Similarly, the maximum operating temperature is typically determined to be the lowest temperature that begins to exceed the capacity of any one component. For example, in some cases the bearings may be the limiting component, while in other cases the fanÕs impeller construction material may be the limiting component. The construction material is perhaps the most obvious element of the fan to consider when dealing with a high-temperature application. In general, aluminum withstands maximum temperatures up to 250 F, standard carbon steel up to 750 F, and 316 stainless steel up to 1000 F. Critical components are many times constructed of ferrous materials to withstand the higher temperatures. If temperatures were to exceed 300 F, for example, aluminum would be eliminated as a construction material option. Other construction considerations include bearing type, drive component selections, means of ventilation and cooling of the drive components, and insulation options.

The most common way of simplifying construction and component specifications to accommodate high temperature applications is to maintain separate categories based on the specified temperature range and time requirements.

Canada Fans has four Heat Option Packages for high temperature operation. Heat Option I construction is designed for continuous operation between 200 F and 500 F. Heat Option II construction meets specifications requiring the fan to exhaust 500 F air for a minimum of four hours in an emergency smoke removal situation per IRI requirements. Heat Option III construction meets the specifications requiring the fan to exhaust 1000 F air for a minimum of 15 minutes in an emergency smoke removal situation per SBCCI. This construction also surpasses the IRI requirements for 500 F for a minimum of four hours. Heat Option IV construction meets specifications for UL Listed ÒPower Ventilators for Smoke Control Systems. This includes the IRI requirement of 500 F for a minimum of four hours, the SBCCI requirements of 1000 F for a minimum of 15 minutes, and the Snow Load Test for butterfly dampers in UL-793.

While it may be tempting to choose a higher heat option than necessary “just to be safe”, doing so can add considerable and unnecessary cost to the job. For example, selecting HT Option III when HT Option II is adequate adds insulation and high temperature bearings. These items would be considered “overkill” and add unnecessary extra costs.

For additional information please refer to http://www.northernindustrialsupplycompany.com/products/industrialfan_blowers.html

Oleg Cthetchel
Industrial Process Engineer
airknife@cogeco.ca
Northern Fan Co.
http://northernindustrialsupplycompany.com/products/index.html
http://northernindustrialsupplycompany.com/products/industrialfan_blowers.html

High Temperature Exhaust Fan

airknife@cogeco.ca

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buffalofancom

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Industrial Extractor Fans

Industrial extractor fans come in a wide variety of shapes, sizes, and strengths so it can be difficult to choose the best one for your restaurant kitchen. There are roughly seven different sizes that are available from 315mm to 630mm which can be mounted in a few different ways. Many businesses prefer the axial style of fan as it can be used for a wide range of applications. This article will discuss these machines and hopefully make your choice of fan a bit easier.

One of the common drawbacks of industrial extractor fans is how loud they are. This can be such a problem that most restaurant managers choose to run them only when the amount of steam, smoke, and pollutants in the air reaches an intolerable level. However, there are some high end models that can run in a Quiet Mode that doesn’t make that much noise at all and even can be run all the time if you choose. You may even want to run the fan a bit after your staff has finished for the day in order to clear up any residual pollutants that may remain in the air.

If you are currently looking at the different options of industrial extractor fans you have available, you will have to decide whether you would like a model that uses ducts or one that uses filters. The former choice is the most efficient as it can take the polluted air directly out of your building and replace it with clean air. Your other option, the filtered models, do not do as well because they will recycle the same air within your building only they run it through a charcoal filter first to make it cleaner. While a ducted model is preferred in most situations, they can be a bit more on the expensive side. Not to mention, you may not have the space necessary to fit the ducts.

It is important that you find industrial extractor fans that have been built to last. Therefore, try to find a model that is built from steel as this is a durable metal that is sure to last. Also be on the lookout for one that is coated in corrosion proof paint and has steel wire guards as well for optimum protection. It is also a good idea to pay special attention to the kind of motor each model features. Try to find one that is lightweight, but works well and is built to last.

One final thing you will have to take into consideration is how you will install your fan. You will find that most axial industrial extractor fans may be installed in various ways such as:

– Mounted on the wall with special brackets

– Placed freestanding in the center of the room

– Hung from the ceiling with chains

– Inline with your ductwork

Additional information can be found at the Industrial Fan Blower company web site http://www.industrialfanblower.net/Index.htm

Oleg Tchechel
Developer of Industrial Air Make-Up Units
Industrial Fan Blower Co.
asap@buffalofan.com
http://www.industrialfanblower.net/cbd_products_std.htm
http://www.industrialfanblower.net/cbd_products_heavy.htm

Industrial Extractor Fans

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Industrial Ventilators for Ventilation

Industrial ventilation is of paramount importance to ensure the safety and well-being of employees. In industries where employees are subjected to dangerous chemicals, vapours and gasses on a daily basis, effective industrial ventilation can mean the difference between life and death. The basic concepts behind industrial ventilation are quite simple, but for it to be effective, the ventilation system needs to be installed by an experienced engineer.

Industrial Ventilation Methods

Industrial ventilation is a method of controlling employee exposure toxic chemicals, volatile airborne substances and flammable vapours by removing the contaminated air and replacing it with clean, fresh air. Used in a variety of different industries where poisonous vapours may be a problem, industrial ventilation is most often employed to remove welding and solvent vapours, oil mists and poisonous or volatile dust.

But, industrial ventilation may not always be necessary. True, it should be preferable for the continued health of your employees, but regulations suggest that industrial ventilation only becomes compulsory when:

•the levels of contaminants exceed regulated levels;
•the lower explosive limit of flammable vapours is exceeded; or
•when the oxygen concentration in an area drops below 19.5%.

Industrial ventilation should also be considered before respirators. Not only is the system easier to maintain, but, in the long run, is a much more cost effective method of air purity control.

Industrial Ventilator Options

There are a number of industrial ventilation options available depending on the circumstances of your industry’s circumstances. The most basic is indoor quality ventilation that aims to provide fresh air throughout a building as part of the existing ventilation system. This option is primarily used in offices but can be effective in small industries where the concentration of contaminants is low.

Easy to maintain and inexpensive to set up is dilution ventilation. This form of industrial ventilation uses large and powerful exhaust fans to extract contaminated air and to draw in clean air. It is very effective in clearing flammable vapours but is less effective for metal fumes or large concentrations of highly toxic materials. Depending on where the industry is located, the incoming air may require a lot of cooling or heating before it can be introduced into the industrial ventilation system, increasing the cost of using the system.

Dilution Ventilation Principles

Dilution ventilation uses the simple principles of displacement and dilution to function. Some of the contaminated air is removed and replaced with large amounts of fresh air. The concentration of the contamination is effectively lowered, making it safer for people to work in the area.

A more localised industrial ventilation system is local exhaust ventilation. This system captures the contaminations at the source and expels it before it has a chance to disperse into the air. For highly toxic contaminants or high concentrations, this industrial ventilation is probably one of the best. It does not require large amounts of fresh incoming air since the exhaust of contaminants is localised. This effective ventilation comes at a higher cost and more frequent maintenance, however.

Local Exhaust Ventilation

Local exhaust ventilation works like a vacuum cleaner forcing contaminated air to move from a high concentration to a low concentration. It is perhaps one of the most effective industrial ventilation systems because it removes the contaminants at the source before it has a chance to spread.

There are effective industrial ventilation systems available for any industry. Some are simple to use, like dilution ventilation, while others are specifically made for highly toxic environments, like local exhaust ventilation. Whatever the decision, as long as the industrial ventilation keeps your employees safe from the contaminations of the substances they work with, it is doing its job.

For additional information please refer to http://www.industrialblowerfan.com/projects.html

Susanna Terlitskaia
Industrial Ventilating Engineer
Industrial Blower Fans Company
nis@primus.ca
http://www.industrialblowerfan.com/air-cooling-unit.html
http://www.industrialblowerfan.com/roof-extractors.html

Industrial Air Ventilation

nis@primus.ca

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Mixed Flow Inline Fans

Made by Canada Fans Co. high pressure MVA series mixed flow inline ventilators finally resolves the problem of pushing air through high resistance and long ventilation ducts.

Mixed Flow fans are an excellent choice for return air, supply, or general ventilation applications where low sound is critical. As compared to similarly sized tubular centrifugals and vane axials, a mixed flow fan will be 5-20 dB quieter! In addition, the mixed flow wheel is extremely efficient and will cut down on operating expenses.

Unique features of the MVA Mixed Flow Fans include:

– Universal Mounting System that allows the unit to be field rotated at the job site
– Compact design with standard slip-fit duct connections for ease of installation
– UL/CSA listing for electrical is available
– Continuously welded housing with a standard powder paint finish suitable for indoor or outdoor applications
– A complete three plane vibration test of all assembled fans prior to shipment

Mixed Flow Inline Fan: Model MVAB:

* Belt drive construction with motor out of the airstream
* Air Handling Quality bearings selected with a minimum life in excess of L(10) 50,000 hours at the maximum operating speed
* Performance capacities from 1,000 to 100,000 cfm (1,700 – 165,000 m3/hour) and pressures up to 8 in. wg. (2000 Pa)

Mixed Flow Inline Fan: Model MVAD:

* Direct drive construction eliminates belts, pulleys, and shaft bearing maintenance
* MVAD design is more compact for space critical application
* Partial wheel widths allow for wide performance capacities ranging from 500 to 105,000 cfm (900 – 170,000 m3/hour) and pressures up to 9 in. w.g. (2300PA)

Vaneaxial Fans

Another in-line fan for for air moving in round ducts by Canada Fans is a high pressure small vaneaxial fan finally resolves the problem of boosting air flow in long ventilation ducts of today’s large residential houses.

For a long time the efficient ventilation of remote rooms in the large houses could be done only with two independent air supply sources (like a furnace). Ventilating ductwork in contemporary large houses becomes so long and elaborated that even a high pressure furnace fan couldn’t generate enough static pressure to blow through the whole length of such a duct. The existing low pressure booster duct fans, even though compact enough to be installed in-line in the house ventilation ductwork, still do not provide enough booster pressure / airflow. The usual solution to this problem was installation of two independent furnaces with different air ducts, which is rather expensive option.

High Pressure Fans

A new high pressure (up to 1.5″ WG) small vaneaxial Series VA fan is an ideal booster fan for prolonged ducts. Unlike inline centrifugal ventilator, that also generates rather high pressure, the air comes out not from a peripheral outlet ring area, but distributes evenly across its outlet opening like in true axial blowers.

The other advantages of VA Series vaneaxial ventilators is their intrinsic spark-resistant construction because of all-aluminum construction; quiet operation of true vaneaxial design; lower energy consumption due to efficient wheel design.

Eight different sizes from 6″ DIA to 10″ DIA offer wide performance range for any ventilation duct design. Direct drive design ensures long live, maintenance-free operation. Explosion proof motors are available too, as well as sliding dampers, various mounting options, additional sound isolation.

For additional information please refer to Canada Fans Co. web site http://northernindustrialsupplycompany.com/index.html.

Oleg Cthetchel
Process Ventilation Engineer
Canada Fans Co.
http://northernindustrialsupplycompany.com/products/industrialfan_blowers.html
http://northernindustrialsupplycompany.com/products/ventilators.html

High Volume Inline Mixed Flow Fans

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fan@cogeco.ca

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Selecting an Industrial Fan

The air delivering capacity of axial flow fans ranges from 100 to 500,000 cubic feet per minute (3,000 to 15,000 cubic meters per minute). Impellers usually have blades with airfoil cross-sections.

Axial Fans

In an axial fan, the effective progress of the air is straight through the impeller at a constant distance from the axis. The primary component of blade force on the air is directed axially from inlet to outlet and thus provides the pressure rise by a process that may be called direct blade action.

The blade force necessarily has an additional component in the tangential direction, providing the reaction to the driving torque : this sets the air spinning about the axis independently of its forward motion.

As compared to curved sheet blades, aerofoils can apply greater force to the air, thereby increasing maximum pressure and can maintain better efficiency over a wider range of volumetric flow. Also by increasing the thickness & curvature of the inner sections, the blades can be made stiffer, this limits flutter and allows the impellers to be run at higher speeds.

Selection of a a right fan one should consider such factors like cost optimization, power rating & noise levels govern the selection of a fan suitable for a given application. Various combinations are possible to meet any given duty or operating requirements for best performance, lesser noise, power and cost characteristics.

Once the volume of airflow and the static pressure of the system are known, it is possible to specify a fan. The governing principle in fan selection is that any given fan can only deliver one flow at one pressure in a given system. To select a fan one must consider the following parameters:

– total airflow required

– total operating pressure

– fan installation space

The fan efficiency is defined as the ratio of air power (output) to shaft power requirement (input). An optimally designed fan impeller with improved aerodynamics requires less shaft input power for desired delivery of air volume with total pressure rise as per the system requirement. With reduced shaft power requirement, there is a commensurate reduction in energy consumption.

Thus the fan efficiency is directly contingent upon selection of fan and the operating point relevant to the system resistance.

The way fan impellers (blades or rotors) are designed, the amount of air they can move decreases as the pressure they are working against increases.

The airflow vs. pressure information for a particular fan is called the fan performance data. The performance of a fan depends on the size, shape & speed of the impeller. The fan performance data is essential for selecting fans as per the desired airflow and system pressure.

Most fans are tested using procedures specified by Air Movement and Control Association International Inc. (AMCA), Illinois, USA. The fan under test is mounted near the outlet of the test rig and air in-flow through the rig is varied by the movable gate assembly situated at the other end of the test rig.

The airflow through the rig is determined by measurement of the pressure differential and simultaneous readings are taken of the static pressure developed by the fan, air velocity at the exit side, power consumed by the fan driving motor etc.

Fan performance curves and data show how much pressure and airflow a given fan can produce at a given speed. This data is based on the system resistance (pressure) occurring away from the fan. Fan performance curves are developed by fan manufacturers based on the testing of a prototype fan fabricated based on the theoretical design.

The axial flow fans are widely used for providing the required airflow for heat & mass transfer operations in various industrial equipment and processes. These include cooling towers for air-conditioning & ventilation, humidifiers in textile mills, air-heat exchangers for various chemical processes, ventilation & exhaust as in mining industry etc. All the major industries use large number of axial flow fans for operations, such as :

– Power generation

– Petroleum refining & petrochemicals

– Cement industry

– Chemicals & pharmaceuticals production

– Fertilizer production

– Mining manufacturing

– Humidification in textile mills

– building Ventilation, etc..

For additional information please refer to Northern Industrial Co. web site http://northernindustrialsupplycompany.com/index.html

Oleg Cthetchel
Process Ventilation Engineer
Northern Industrial Co.
http://northernindustrialsupplycompany.com/products/industrialfan_blowers.html
http://northernindustrialsupplycompany.com/products/ventilators.html

Selection of Appropriate Axial Fan for Building Ventilation

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fan@cogeco.ca

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