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Selecting the Right Fan for Enhanced Air Quality: Part II – Key Parameters to Consider

Selecting the Right Fan for Enhanced Air Quality: Part II - Key Parameters to Consider

In our previous article, we discussed types of fans and recommendations for choosing the right fan selection for the right application. When we need to consider selecting the right fan for enhanced air quality, some key and important parameters need to be taken into consideration, We will discuss here the key parameters for selecting the right fan for enhanced air quality as well as explore more about configurations and types of drives for fans, which have a significant impact on the performance of the system as a whole.

Selecting the right fan: List of Key Parameters: ​

For enhanced air quality, we considered the key parameters for selecting the right fan, which are listed below.

Capacity:

Capacity involves flow rate based on actual cubic feet per minute (acfm) to the fan inlet.The water gauge measures flow rate and pressure requirements at standard conditions (0.075 Ibm/ftl) using FTP and FSP. If the required pressure is unknown under non-standard conditions, density correction is made to ensure accurate measurements.

  • Air stream Handled Through the Fan
  • Explosive or flammable material
  • Corrosive Applications
  • Elevated air stream temperatures

Air stream handled through the fan:

It involves the following:

Air Stream and fan to be used

Explosive or Flammable Material:

Always use spark resistant construction (use explosion proof motor if motor is in air stream. Always stick to the standards set by the National Board of Fire Underwriters, the National Fire Protection Association, and governmental regulations.

Corrosive Applications:

It may require a protective coating or special materials of construction (stainless, fiberglass)

Elevated Air Stream Temperatures:

Use the correct materials for construction, arrangement, and bearing types because the maximum operating temperature affects the strength of the materials.

Physical Limitations:

Physical limitations must be considered in fan selection. Fan size, inlet size and location, fan weight, and ease of maintenance are the important things to be considered along with performance requirements.The most efficient fan size may not fit in the available physical space.

Drive Arrangements:

In a packaged fan system, the drive arrangement, i.e., the motor, is provided by the manufacturer, but if you purchase an assembled unit, then you must make drive arrangements according to the motor type, such as:

  • Direct Drive
  • Belt Drive

Direct Drive provides a compact assembly with constant fan speeds, ensuring optimal motor performance despite variations in impeller geometry and motor speed.

Belt drive offers flexibility in fan speed. This can be done by altering the drive ratio. Some applications need flexibility in fan speed because it requires changes in system capacity or pressure requirements due to changes in process, hood design, equipment location, or air cleaning equipment.

Noise

Fan noise, generated by turbulence within the fan housing, varies by fan type, flow rate, pressure, and fan efficiency. Noise ratings must be obtained from the fan manufacturer, as each fan design is different. Most fans produce a "white" noise, a mixture of all frequencies, and radial blade fans also produce a pure tone at a frequency equal to the blade passage frequency (BPF). The backward inclined impeller design is generally the quietest, but non-uniform air flow at the fan inlet or outlet can increase fan noise level. Most fan manufacturers publish sound ratings, such as sound power levels for eight ANSI standard octave bands in decibels (dB). The surrounding environment affects the sound level, and the decibel unit is not interchangeable for sound power or sound pressure. Sound pressure levels are usually measured in dB using the "A" weighting scale, which closely reflects the human auditory response to noise of various frequencies.

Safety and Accessories:

Safety guards are required as per the latest government norms implemented everywhere. All the danger points, such as the inlet, outlet, shaft, drive, and cleanout doors, must be checked as per the safety guidelines. Accessories can help with installation as well as maintenance requirements. Examples of accessories include drains, cleanout doors, split housings, and shaft seals.

Flow Control:

To control the airflow of a fan, there are some accessories to be installed, such as dampers, variable-pitch blades, and speed control.

Dampers:

Dampers are part of the air stream so they are installed directly on the fan inlet or outlet. Dampers are made up of material, which may not be acceptable for material handling fans.

Advantages of Dampers:

  • Dramatic Power Supply and Noise Reduction
  • Simple installation.
  • Lower initial costs.

Dampers are of two types:

Outlet Dampers:

The selection of outlet dampers depends on the required resistance, with parallel and opposed blades available for optimal control.

Inlet Dampers:

Inlet dampers reduce fan output and operating horsepower by pre-spinning air into the fan inlet, ensuring power savings for extended periods of operation.

Variable Pitch Blades:

Variable-pitch impellers enable manual or automatic changes to blade pitch, allowing for pneumatic or hydraulic adjustments while the fan is operating.

Variable Frequency Drive (VFD)

In flow control, a VFD (variable frequency drive) is also used as an accessory to control the flow of a fan, so the VFD is also an important parameter in fan selection.VFD applications vary fan speed and fan static pressure by controlling voltage and frequency between the electric power source and fan motor. The fan speed varies linearly with line frequency, with most VFD applications using direct drive arrangements. Belt drives are occasionally used.

VFD's intended usage requires understanding of the building's power supply and other electrical equipment usage. In applications with 80% or more system air flow, an inlet damper may be a better choice.

In short, the following parameters are more important in selecting the right fan:

When we think about a clean air system, there are numerous factors to be considered for optimal performance of the system. The selection of fans is one of them. Here are some factors responsible for these fan selections:.

Volume Flow Rate:

Make sure the fan has sufficiently high air speed and air flow for optimal performance of the system.

Pressure:

The amount of pressure needed to move air through the ducting and any filters,dampers, or other obstructions in the ventilation system.

Type of Air stream Handled:

The type of air that needs to be moved.

Space Limitations:

Available amount of space for the fan.

Efficiency:

The fan’s efficiency depends on the design and type of fan.

All the above factors are most important in selecting the right fan or blower for the clean air system.

How can you select the right parameters among all to select the right fan?

With so many deciding factors and parameters, how can one choose the right parameters to choose the right fan for a clean air system? Here, Filter On’s expert guidance came into play. Filter On assesses requirements and gives you expert guidance to choose the right fan for a clean air system.

Filter On will assess:

  1. Statically and dynamically balanced fans, optimized with careful selection of operating points.
  2. Optimal VFD ensures further power savings.
  3. Fans are selected for optimized performance and require less power.

Thus, Filter On uses their 40+ years of expertise to help you decide the right fan for a clean air system.

In the next article we will explore more about fine tuning of fans for optimum performance of the system.

Filter On India has been working towards “Mission Zero Pollution” for the last 40+ years as a clean air solutions partner for industries. We specialize and have expertise in welding fumes, oil mist, coolant mist, dust collection, soldering, laser marking, laser cutting, plasma cutting, fumes in fastener manufacturing, ball point tip manufacturing, oil quenching, kitchen fumes, etc. Filter On has 70+ clean air solutions, so you can contact us for more information about our solutions. You can reach us through the web or visit us at our corporate office at Pune and our virtual locations at Delhi, Bangalore, Ahmadabad, Hyderabad, or Chennai locations.

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Optimizing Air Quality: An Extensive Guide to Fan Selection for Clean Air Systems (Part I)

Optimizing Air Quality: An Extensive Guide to Fan Selection for Clean Air Systems (Part I)

We discussed the selection of filtration systems in the previous article. Fan selection is most important in ventilation when we talk about air-moving devices, selection of fan is most important because it has impact on the overall performance of the clean air system, However fan selection is difficult task, so some expert guidance is necessary. Here in this article we will discuss types of fans, some guidelines about how to choose right fan for right application? Etc..

Classification of fans for fan selection

Fans are the primary air-moving devices in industrial applications, so they have been classified into three basic groups:

  • Axial Fans
  • Centrifugal Fans.
  • Special Type Fans

Axial Fans

Industrial Tube Axial fan
Industrial Axial fan

Axial fans are used for high flow rates at lower resistance. Axial fans are of three types:

  • Propeller Fans
  • Tube axial Fans
  • Vane axial Fans

Propeller fans are essential for general ventilation, utilizing blade types like disc or propeller blades for low resistance. Performance is sensitive to resistance, affecting flow rate.

Tube axial fans, also known as duct fans, are fans designed to move air against moderate pressures, typically with narrow or propeller-type blades in a short cylindrical housing.

Vane axial fans, typically mounted in cylindrical housings, are highly efficient and typically used in clean air applications due to their higher pressures.

Types of centrifugal fan

Forward Curve (Squirrel Cages):

Squirrel cages, with their low space requirements and quiet operation, are ideal for low to moderate static pressures in heating and air conditioning work but not recommended for dust or particles that could cause unbalance.

Radial Impellers:

Radial impellers offer a variety of blade shapes, ranging from high efficiency to heavy impact resistance, designed for exhaust systems. These radial blades, with medium tip speeds, handle both clean and dirty air, ensuring efficient material conveying velocities.

Backward-inclined or backward-curved impeller blades

These blades are inclined oppositely to the direction of fan rotation. These types of fans have higher speeds, efficiency, and relatively low noise levels with non-overloading horsepower characteristics.

These impellers have two types:
  • Single-thickness blades and
  • Airfoil blades.

Special Type Fans:

Special Type Duct Fans

Special-type fans, such as in-line centrifugal and vane axial fans, feature backward-inclined blades and similar performance curves to scroll-type centrifugal fans.

Thus, it is very important to choose the right type of fan for the right kind of application. For example, choosing a forward-curved fan for fume and dust handling will definitely be the wrong choice, as it would lead to the deposition of particles on forward-curved blades and thus imbalance.

How do I select the right fan for the right application?

In conclusion-
  • Choose an axial fan for low-pressure and high-volume clean air ventilation applications (like underground parking or tunnel exhaust ventilation).
  • Choose centrifugal forward-curved fans for fresh air low-pressure applications. You will find these fans most commonly used for small AC units, coolers, etc.
  • Choose centrifugal backward-curved fans for medium-pressure and low- to high-volume applications. These are most commonly used for industrial fume extractors, dust collectors, AHUs of central AC systems, etc.
  • Choose centrifugal radial fans for material movement like pneumatic conveying, dust handling systems, powder handling systems, etc.

In the next article we will explore more about configurations and type of drives of fans which has a significant impact on performance of the system as a whole.

Filter On India has been working towards “Mission Zero Pollution” for the last 40+ years as a clean air solutions partner for industries. We specialize and have expertise in welding fumes, oil mist, coolant mist, dust collection, soldering, laser marking, laser cutting, plasma cutting, fumes in fastener manufacturing, ball point tip manufacturing, oil quenching, kitchen fumes, etc. Filter On has 70+ clean air solutions, so you can contact us for more information about our solutions. You can reach us through the web or visit us at our corporate office at Pune and our virtual locations at Delhi, Bangalore, Ahmadabad, Hyderabad, or Chennai locations.

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Designing A Complete Clean Air System: A Guide To Effective Planning

Designing A Complete Clean Air System: A Guide To Effective Planning

Planning is the first step when you think of any new project or anything that needs to be organized, e.g., if you want to organize a workshop on some industrial topic, then you are required to plan accordingly the most important things to perform that workshop, i.e., the date and time of the workshop, the venue, the visiting guest, the number of attendees, and so on. Similar things are also applicable when you plan a total clean air project solution. In industries where continuous production is on, a number of applications (welding, brazing, gauging, soldering,laser cutting, plasma cutting) are performed every day. Fumes generated in these applications are hazardous in nature for the operator or worker, and, due to this, the whole work environment is disturbed, so planning to install a clean air solution is a mandatory task for the maintenance manager of that industry. We are here discussing how we can plan a specific clean air solution.

Why is planning a clean air solution important ?

One of the biggest reasons for failure to implement clean air systems in manufacturing industries is a lack of awareness about the importance of the planning phase. Because of this, the implementation of clean air systems is done in a very haphazard manner with a fragmented approach. The result is that resources are spent without much result on the ground. This can be avoided if proper planning for clean air systems is made.

What to Plan for Clean Air Systems?

The final objective of any clean air system implementation is to minimize exposure to air pollution for people working in close proximity to various processes and ensure protection of their health and productivity. Thus, the plan should be aligned with this objective. There are certain standards set for ambient air quality that are recommended to be followed by global bodies like ACGIH (American Conference of Governmental and Industrial Hygienists), OSHA, ISO, etc., which are also adopted by local regulatory authorities like the Factories Act and CPCB.

The first step in planning the systems properly is to check the actual air quality at the workplace and compare it with the standard’s requirements. This will bring visibility to where the gaps in compliance are. Which stations are most polluting? And such stations would be the best candidates to start the implementation of clean air systems, as they will give maximum returns on invested resources.

This exercise is known as air quality mapping. FilterON provides this service with the help of a real-time laser aerosol monitoring system. This exercise would provide very important baseline data on pollution levels at each station for the users, which can be a great input for decision-makers.

How is air quality mapping done?

A Filter A representative with expertise in the air pollution control system sector will take samples from each and every robotic and manual welding station. With the help of a portable digital aerosol monitor, the reading of air quality in terms of mg/M3 of dust concentration is recorded. These readings are plotted on the layout and marked as red, yellow, and green categories.

Red: Pollution levels are way higher than the requirements of the standard

Yellow: pollution level on the borderline of the upper limit recommended in the standard and

Green: pollution levels below the limits mentioned in standards (i.e., safe air quality).

This mapping exercise will be followed by a recommendation and a report regarding:

To reduce pollution levels drastically, where should I focus the resources most?

Which type of system would be best suited for the said applications?

This exercise would help users define the requirements of clean air systems more objectively and rationally, and it would be a great planning tool for the implementation of effective clean air systems.

How does air quality mapping help in planning clean air solutions?

  • AQ Map can help identify the ‘hot spots’ i.e., workstations generating the highest pollution in the layout
  • Can help the planners ‘prioritize’ the budgets for these ‘hot spots’ so that maximum effectiveness can be achieved in any given budget.
  • Generally, 20% of the workstations in the layout will be responsible for generating 80% of pollution. The AQ Map helps the planner identify those 20% of workstations for ‘targeted action'.
  • It helps the planners to chalk out the ‘Clean Air Plan’ and implement it phase-wise. The AQ Map becomes an effective tool for monitoring the progress of such a plan.

Filter On India has been working towards “Mission Zero Pollution” for the last 40+ years as a clean air solutions partner for industries. Filter On has 70+ clean air solutions, so you can contact us for more information about our solutions. You can reach us through the web or visit us at Pune, Delhi, Bangalore, or Chennai locations.

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