Criteria for Fan Selection

SELECTION BASIS FOR FANS

While selecting the fans, there should be various considerations that we have to take care of:

Noise: If we select fans that match the DB for a particular CFM, it automatically is high efficiency, has good motors, and so on. 1m or 3m standard.

Take care of the standards of Motors and Fans. 

Access for Maintenance. 

Take care of Overloading or Non-overloading Fans.  Forward curved fan is overloading while backward and airfoil type is non-overloading. It means if the forward-curved fan is used in low static pressure, CFM flows through it is higher than designed and large current is drawn and the circuit may get damaged. 

Type of Fans: 

1. DIDW/SISW
2.  AXIAL Vs Centrifugal: Axial fan has blade base along the circumference and centrifugal has blade base along the axis. An axial fan is used for straight ducts if used in the ducting system. Otherwise, it is used for the low-pressure system. The centrifugal fan especially the forward-curved fan cannot be used without a duct. The backward curved centrifugal fan is a non-overloading fan. So, even with less pressure, it can function wel
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4. Double Skin Vs single Skin
5. Forward Curved Vs Backward curved Vs airfoil type Blade: Forward curved Blade type fan is used in Low flow, high-pressure system. Don't use it in a low-pressure system. It will overload. Airflow in the forward-curved fan is tangential while backward-curved is radial. 
6. Direct Driven Vs Belt Driven    Defined: In a belt driven configuration, the motor exists independently of the fan blades and at least one belt – sometimes more – connects the motor to the fan’s moving parts.

7. Pro: Belt-driven fans offer greater flexibility in terms of RPM speed. Generally, such fans are cheaper than direct drive fans of comparable size. They’re also typically more silent than the alternative.

   Cons: More friction between moving parts, which can lead to more maintenance and higher energy costs.

   Direct Drive

   Defined: In a direct drive configuration, the fan motor that controls the movement of the fan blades is connected either to a shaft or fan axle. Thus, the fan blades will rotate at the same speed as the motor rotates.

   Pro: Greater efficiency is the biggest pro of direct drive fan configurations. Unlike belt driven fans, there’s less energy loss because there’s a reduced amount of friction as the fan operates. There’s also no belt residue and these fans cost less to maintain, generally speaking, because belts don’t wear down and break. Additionally, they’re easier to clean.

   Con: Lesser flexibility compared to belt-driven fans. Also maybe more expensive when similar direct drive and belt-driven fans are compared side-by-side. Direct drive units are also louder than their belt drive counterparts.

8. VFD Vs without VFD.
9. Inline: Axial, Inline Vs Centrifugal Inline Fan: Inline fan is a fan that is connected to the ducts in supply as well as a suction side in the same line i.e. straight line. 
10. Cabinet Vs rectangular: Cabinet means just covered while rectangular means definite rectangular shape. 
11. Ceiling Suspended Vs Floor Mounted.
12. Number of Poles.

STANDARDS FOR FANS

AMCA: Air Movement and Control Association.

IE standard: Standard for Motor Fans: 

 There are many criteria for the selection of Fans. We must take care of the following factors while selecting.

Axial Fans: axial fans in the low-pressure range (up to 100 mm H2O) are much more frequent. Noisy. They are used where more air displacement is necessary.

Inline Fan: Connected by Ducts: Remote fans

Propeller Fans: They experience a large change in airflow with small changes in static pressure. They handle large volumes of air at low pressure or free delivery. Propeller fans are often used indoors as exhaust fans. Outdoor applications include air-cooled condensers and cooling towers. Efficiency is low.

SISW/DIDW: same pressure rise but Double Volume in case of DIDW.

Centrifugal Fans: they have higher pressure and lower airflow capabilities than axial fans. A steady flow of air and hence comfortable. For high pressure.

 In-line duct fans are used to transport air via ventilation ducts. Inline fans remove stale fumes, smoke, and odor from the closed spaces and improve air quality. It allows fresh air to rush into the spaces Inline fans are useful for applications that include:

• Ventilation of wet spaces such as bathrooms, kitchens and laundries
• Remote fans for kitchen range hoods
• Duct boosters for ventilation systems and clothes dryers
• Supply or exhaust fans for continuous whole-house ventilation
• Radon mitigation systems.

Inline fans come in many different configurations, sizes and capabilities to meet a wide variety of ventilation needs. They are available as simple single-port versions or versatile multiport versions. Single-port units have one incoming supply duct and one outgoing exhaust duct. Multiport versions have multiple ducts with a minimum of one inlet and one exhaust. A single fan can then manage air movement to or from multiple locations (e.g., two bathrooms). By varying duct sizes, inserting “Y” fittings to branch duct runs, employing adjustable grille openings, and varying the fan speeds, different ventilation rates are possible for each location connected. Multiport versions offer ventilation capacity appropriate for larger-scale single-family, multifamily, and commercial buildings.

Inline fans are available in a range of airflow capacities from about 100 CFM, suitable for many housing needs, to 2,000 CFM for commercial applications. Manufacturers offer a variety of sizes, flow capacities, ducting configurations, controls, and accessories.

Application:

If more static pressure duct and steady Flow: Inline Fan or Centrifugal Fans

If more Volume and noise is not issue but less static pressure: Axial Fans

Terrace for Protection against Moisture: IP55 Fans

Hotels glass wall and Toilets fans: Propeller fans. They don't use Duct.

Inline Fans: Remote Fans used with Ducting For Exhaust.as bathrooms, kitchens and laundries.

kitchen fresh air: air washer

kitchen exhaust: air scrubber

Overloading and Overloading Fans: 

Overloading fans are those types of fans that supply higher CFM of air in case of low static pressure and hence consume more power or draw more current and its circuit is tripped. 

Non-Overloading Fans: In the case of Low static pressure, despite the larger flow of air, draws the same power or current similar to rated. So, it is not tripped. 

Types of Fans based on tips of Fans:

Airfoil type Blade: Highest efficiency: Non-overloading type

Backward type Blade: Higher efficiency: Non -overloading type

Forward type Blade: Lower efficiency: Overloading type

IP Rated Fans:

IP55 means Dust Protected & protection against water jets from any angle. 

INLINE FANS

Inline fans are mounted in-line with the ductwork, bringing air from the inside and to the outside of the home. An inline fan may also be described as a remote-mounted fan.

Axial Inline Fans

Axial fan motors are generally suited to applications that require high extraction at a low pressure. Low pressure means that the fan is not particularly well suited when a long duct run is needed. View our range of axial fans here.

Well suited Applications for an Axial motor
A small toilet
A small bathroom, ensuite or laundry
An installation that has minimal ducting (less than a few meters).

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Centrifugal Inline Fans

A centrifugal extraction fan motor is the opposite to an axial motor in terms of its characteristics when dealing with pressure. The centrifugal motor has been engineered to operate with long duct runs which may have bends, junctions and multiple inlets/outlets. View our range of centrifugal fans here.

Well suited Applications for a Centrifugal motor
Large heat transfer systems
Large Sub floor ventilation systems
Servicing a large area
An installation that has a vast amount of ducting (20 meters or more)

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Mix-flow Inline Fans

Mixed Flow Inline exhaust fans are a mixture between the Axial and Centrifugal models. They have good airflow and good pressure characteristics, can be used for longer runs of duct, bends, branches, etc. They show centrifugal fan characteristics from a size of 150mm upwards and axial fan characteristics for sizes smaller than 150mm. View our range of mix flow fans here

Well Suited Applications for a Mix Flow Motor
Medium/Large bathroom, ensuite or laundry
Installation that has a moderate amount of ducting (from 0-20 meters approx)

Material handled through the fan

• If the exhaust air contains a small amount of smoke or dust, a backward inclined centrifugal or axial fan should be selected.
• If the exhaust air contains light dust, fume or moisture, a backward inclined or radial centrifugal fan would be preferred.
• If the particulate load in the exhaust air is high or when material is handled, the normal selection would be a radial centrifugal fan.
• If the exhaust air contains explosive or flammable material, spark resistant construction (explosion proof motor if the motor is in the air stream) should be selected to conform to the standards of the National Fire Protection Association and provincial governmental regulations.
• If the exhaust air contains corrosive contaminants, a fan with a protective coating or made of special materials (stainless, fiberglass, etc.) may have to be used.

IE class:

IE1 Motors (Standard Efficiency Motors)

The IE1 motors lie in the IE1 class of the international efficiency standard. The output of the IE1 motors is 0.75kW to 355kW. The poles for the IE1 motors are 2, 4, 6, 8, 10 and 12. The speed range of the IE1 motors is from 500rpm to 3600rpm. The rpm frequency for IE1 motors is 50Hz or 60Hz. The aluminum frame size for IE1 motors are 56-200. The cast iron frame size for IE1 motors is 80-400. The temperature class for IE1 motors is B class. The cooling technology for the IE1 motors is IC411. The insulation class is class F. The duty type of the motors is Type S. The protection technology used in IE1 motors is IP55, IP56, IP65, IP66. The international standards for IE1 motors include IEC 60034-30 and IEC 60034-2-1.

IE2 Motors (High Efficiency)

The IE2 motors lie in the IE2 class of the international efficiency standard. The output of the IE2 motors is 0.75kW to 355kW. The poles for the IE2 motors are 2, 4, 6. The speed range of the IE2 motors is from 1000rpm to 3600rpm. The rpm frequency for IE2 motors is 50Hz or 60Hz. The aluminum frame size for IE2 motors is 80-160. The cast iron frame size for IE2 motors is 80-400. The temperature class for IE2 motors is B class. The cooling technology for the IE2 motors is IC411. The insulation class is class F. The duty type of the motors is Type S. The protection technology used in IE2 motors is IP55, IP56, IP65, IP66. The international standards for IE2 motors include IEC 60034-30 and IEC 60034-2-1.

IE3 Motors (Premium Efficiency)

The IE3 motors lie in the IE3 class of the international efficiency standard. The output of the IE3 motors is 0.75kW to 355kW. The poles for the IE3 motors are 2, 4, 6, 8. The speed range of the IE3 motors is from 750rpm to 3600rpm. The rpm frequency for IE3 motors is 50Hz or 60Hz. The aluminum frame size for IE3 motors is 80-160. The cast iron frame size for IE3 motors is 80-400. The temperature class for IE3 motors is B class. The cooling technology for the IE3 motors is IC411 and IC416. The insulation class is class F. The duty type of the motors is Type S1, S2, and S3. The protection technology used in IE3 motors is IP55, IP56, IP65, IP66. The international standards for IE3 motors include IEC 60034-1-30.

IE4 Motors (Super Premium Efficiency)

The IE4 motors lie in the IE4 class of the international efficiency standard. The output of the IE4 motors is 2.2kW to 230kW. The poles for the IE4 motors are 2, 4, 6, 8. The speed range of the IE4 motors is from 750rpm to 3600rpm. The rpm frequency for IE4 motors is 50Hz or 60Hz. The aluminum frame size for IE4 motors is 100-160. The cast iron frame size for IE4 motors are 100-315. The temperature class for IE4 motors is B class. The cooling technology for the IE4 motors is IC411 and IC416. The insulation class is class F. The duty type of the motors is Type S1. The protection technology used in IE4 motors is IP55, IP56, IP65. The international standards for IE4 motors include IEC 60034-30-1. 

Power consumption thumb rule:

For free air delivery like wall mounted fan: 10 CFM/watt

For ductable fans: 4-6 CFM/ Watt

For fans with the filter: 2 CFM/Watt

Axial vs Centrifugal Fans

There are two primary varieties of fan, axial fans and centrifugal fans. Pelonis Technologies, Inc. (PTI), a global leader in fan technology for more than 25 years, manufactures both axial and centrifugal fans.

Clear the Confusion — Axial Vs. Centrifugal

To help clear up that confusion, here is a breakdown of the fan types, their benefits, and their uses.

The design and function of a centrifugal fan is very different from those of an axial fan. Their differences make them each suited for different applications and customers are sometimes unclear as to which fan type will best suit their needs.

Axial Fans

Axial fans date back to the horizontally configured windmills of Europe in the Middle Ages. The first electrically powered fans, introduced in the 1880s, were axial fans.

Axial fans are named for the direction of the airflow they create. Blades rotating around an axis draw air in parallel to that axis and force air out in the same direction.

Axial fans create air flow with a high flow rate, meaning they create a large volume of airflow. However, the airflows they create are of low pressure. They require a low power input for operation.

Centrifugal Fans

The centrifugal fan was invented in 1832 by military engineer Lieutenant General Alexander Sablukov of the Russian Empire’s Imperial Russian Army.

Often called blowers, centrifugal fans vary differently from axial fans. The pressure of an incoming airstream is increased by a fan wheel, a series of blades mounted on a circular hub. Centrifugal fans move air radially — the direction of the outward flowing air is changed, usually by 90°, from the direction of the incoming air.

The airflow created by centrifugal fans is directed through a system of ducts or tubes. This helps create a higher pressure airflow than axial fans. Despite a lower flow rate, centrifugal fans create a steadier flow of air than axial fans. Centrifugal fans also require a higher power input.

With a backward curved impeller, the air exits in a radial direction whereas with a forward curved the air exits tangentially from the circumference of the fan. . 

When the required duty point falls in the area of higher system pressures versus lower volume flow on the fan characteristic a single inlet forward curved centrifugal fan should be considered. If the requirement for the application is for a high-volume flow in a restricted space envelope a double inlet forward curved centrifugal fan should be considered.

Fan Applications

Axial

Because of the low-pressure high-volume airflows they create, axial fans are best suited for general purpose applications. For example, they excel at moving air from one place to another, cooling confined spaces such as computers, and cooling larger spaces such as workspaces. 

A standard AC model is energy efficient, using no more than 100 watts when on high speed. AC fans can be connected directly to a DC power source, such as solar panels or batteries. Since the end goal in units like vending machines is an even flow of cooling power, an AC fan is the fairly obvious choice.

Currently, vending and refreshment industry leaders are trying to get the new generation excited about their services. As the new, hip crowd grows up attached to their technology, the industry is finding new and exciting ways to get their attention.

Cashless payment options, touch screens, and cell phone payment options are all becoming a part of the vending machine design. Companies like Intel® and Cisco Systems® are getting involved, which means the vending machine now has more and more in common with a computer.

And just like any computer you might have in your office, overheating becomes a larger concern with all this technology is included in the new designs.

With demanding technological features, you can see a drop-off in performance due to heat. AC fans are an excellent choice to maintain just the right amount of cooling for these components.

It’s for all these reasons, that we created the PM1225-7 series axial AC fan.  Axial AC fans are used extensively in vending machines to provide cooling where enclosure space is limited.

Centrifugal

Because of the high pressure they create, centrifugal fans are ideal for high pressure applications such as drying and air conditioning systems. As all of their moving parts are enclosed and they also have particulate reduction properties that makes them ideal for use in air pollution and filtration systems. Centrifugal fans also offer distinct benefits:

• First-rate energy efficiency. Constant airflow allows centrifugal fans to generate energy that reaches up to 84% static efficiency. These higher efficiency levels are ideal for sustaining larger air systems.

• Enhanced durability. These fans are durable enough to properly operate in the most corrosive and erosive environments.

• Ability to restrict overloading. Certain centrifugal fans are fitted with non-overloading horsepower curves will ensure the motor will not overload if its capacity is exceeded.

• Easy to maintain. Lighter material fans can be easily cleaned when you deem it necessary. Moreover, certain fans have self-cleaning characteristics, making daily maintenance that much easier.

• High versatility. Centrifugal fans are useful for multiple airflow/pressure combinations, and they can process several airflow conditions, including clean, dry, and wet air

• Multiple sizes. These fans are available in several sizes to accommodate diverse applications—such as those found in tight spaces or difficult to reach areas.