When designing their latest fan, Ziehl-Abegg developed an aerodynamic impeller based on the wing of an owl. The results are stunning, with minimal noise and maximum energy efficiency, meaning the Owlet fans really are the fan of the future.

Electronically commutated direct-current, external rotor motors, the Owlet fans combine Ziehl-Abegg’s pioneering ECblue technology, featuring:

• Highest motor efficiency
• High flexibility due to add-on modules
• As simple as AC technology

Visit the Ziehl-Abegg website to find out more.

With Ecodesign Directive 2009/125/EC (Energy related Products) the European Union has defined requirements for the environmentally sound design of energy consuming products. This directive is part of the 20-20-20 target, according to which energy use should be reduced by 20% and the share of renewable energies increased by 20%, by 2020. It replaces the EuP Directive 2005/32/EC, which referred to a range of electrical products, mainly end user appliances. Concrete measures will be defined through more detailed regulations, but in the first stage, starting January 01, 2013, fans with input power ranging from 125 W to 500 kW will have to meet specific efficiency values. On January 01, 2015, the second stage, with higher efficiency values, becomes effective.

IEC-motors

Since June 2011, IEC-motors (Standard Motors) have had to comply with the requirements of Directive (2009/640/EC) and have had to reach at least efficiency class IE2 (previously: eff1). New IEC motors of a lower efficiency class were no longer allowed to be marketed within the EU. Moduflow have already converted all fans with IEC-motors to a minimum of IE2- level.

External Rotor Motors

External rotor motors are not affected by Directive (2009/640/EC). However, from January 2013 all fans will have to comply with the ErP Directive for fans (2011/327/EC).

Are There Exceptions?

For the time being, yes:

• Fans which have their maximum efficiency operating point at less than 125Watts
• Fans for high specification requirements such as:
• Explosive atmospheres (ATEX), as defined in Directive (94/9/EC6)
• Dedicated smoke extract
• Ambient temperatures above 100°C
• Fans for railway technology or other mobile applications
• Fans used in toxic, highly corrosive or flammable environments, material handling or in environments with abrasive substances, all of which are available within Moduflow’s range.

The following end products are also currently excluded – roof fans, duct fans, tube fans and box fans.

In the future these end products will be covered by a specific regulation. Nevertheless, the motor/impeller combinations used in these fans will have to adhere to the existing efficiency values of directive (2011/327/EC) for fans.

Does Existing Equipment Have to Be Retrofitted?

The answer is no. Existing equipment does not need to be retrofitted. Only fans and fan systems marketed within the EU after January 01, 2013 will be affected. There will be a transition period for replacement fans until January 01, 2015, for fans sold into the market before January 01, 2013.

Does the ErP Directive Apply Globally?

The Directive applies to all energy consuming products which are commissioned and installed in the EU. It does not apply to products designated for export out of the EU.

Will Fans Become More Expensive Due to the New Directive?

Costs for fans already compliant with the requirements will not increase with the introduction of the ErP Directive. There may be additional costs associated with mandatory technical modifications for some products, however a return on investment will be achieved in a short timescale by significant improvements in efficiency. Eventually the end user benefits from a reduction in energy consumption costs and the whole environment from reduced CO2 emissions.

How to Identify ErP Compliant Fans

Starting in 2013 you will be able to identify fans which are compliant with the ErP Directive by the CE symbol and efficiency data placed on the product. In addition, all fans supplied by Moduflow Fan Systems will have been checked individually. We are currently working closely with all our suppliers to ensure that each fan is tested and approved. When fans aren’t ErP compliant, we are working hard to ensure that close alternatives are developed and offered to customers.

What Advantages Does the Directive Provide for Me as Customer?

With the application of this legal regulation only energy efficient fans will be able to be sold in the EU. This will allow you to save up to 65% in energy costs, depending on the application. And you don’t need to wait until 2013. Energy efficient fans, especially with EC technology, are already available.

Are All Moduflow’s Products Compliant?

We are working with our suppliers to define compliancy on all our products. Most of our suppliers already have answers on the standard ranges. We have our own technical group responsible for ErP and liaise closely with the Fan Manufacturers Association and other responsible bodies.

What Happens in Cases Where the Fan Is Speed Controlled?

Speed control is an important aspect of the Directive and ISO 12759 allows a compensation factor to be applied to take into account the energy saving aspects of using a Variable Frequency Drive (VFD). VFD means an electronic power converter (also known as an Inverter Controller) integrated – or functioning as one system – with the motor and the fan.

Therefore, compliance may be achieved by using this compensation factor, if Moduflow were to supply the fan with a VFD or by instructing the client that a suitable VFD must be used. The use of VFD may not be sufficient to allow all the fans to comply.

Please note prior to fan selection: If you are not sure whether you need an explosion proof ATEX fan, or need to know the zone in which your application is classified, please consult an official authority in your country.

As of 20th April 2016, the new Directive ATEX 2014-34 EU superseded the previous ATEX 94/9/EC Directive which became legally effective on 1 July 2003.

Understanding the ATEX Directive

ATEX is an acronym derived from the words “Atmospheres Explosibles” and forms part of a European equipment directive known as ATEX 2014-34 EU. The directive covers manufacturing standards and ensures that people are protected against the risk that may be caused by dangerous substances. The directive covers equipment, protective systems, safety devices, controlling devices, regulating devices and components including industrial fans for installation within a system or as standalone components in a hazardous environment. An air movement, or any other application in other markets, will require an explosion proof ATEX fan if there are flammable, combustible gases or dusts present at any time in the airstream. This applies to industrial air movement applications including, but not limited to, machine cooling, process equipment, food processing and manufacturing and electrical cooling. As an example, potentially hazardous particles, such as those found in sugar or flour in food processing applications, should have an explosion proof fan installed within process systems to eradicate the risks as the materials are passed through. Material handling fans can be supplied as explosion proof or standard variants.

The updated Directive places responsibility on manufacturers of flameproof equipment to supply products that comply with specified directive classifications, as determined by the end-user. This now means that fans have to be designed to avoid the risk of electrical, electrostatic, thermal, and mechanical ignition hazards that may occur in specified flameproof Zones, Classifications and Gas Groups. Industrial fans are safeguarded against explosion through the use of aluminium or copper inlet rings, EEX motors and special coatings, please refer to fan specification and data sheet to check a product is suitable before purchase.

For more information please contact a Moduflow Sales Engineer – 01229 835555.

System Performance

In general, fans are selected for their ability to deliver a required air volume flow rate against an estimated system resistance to flow, or pressure. This defines an Operating Point and is usually expressed in m³/h at Pascals, or cfm at inches Water Gauge.

Volume Flow Rate

Volume flow rate is calculated from application data and may be based on a requirement to heat, cool, or ventilate air, ensure even air temperature distribution, or to contain air that has been contaminated.

Where building ventilation is concerned there is a need to extract stale air, fumes and heat at a rate that depends on the purpose of the building. The calculation is based on air changes per hour and may be as few as 1 for a church or 60 for a furnace room.

When extracting a known amount of heat from, for example, a power electronic enclosure, the minimum volume flow rate for a given permitted temperature rise may be calculated using a formula that takes account of the density and specific heat of air.

For a laboratory fume cupboard, or hood, the flow rate is calculated from knowledge of the minimum air speed required to contain fumes at the open sash of a fume cupboard, or through the inlet area of a hood.

Pressure

Pressure loss is the resistance to air flow and is caused by molecular friction and surface friction as air passes through a system. It is expressed in Pascals (Newtons/m²) or inches Water Gauge and varies with the square of the air velocity. Thus, doubling the flow rate through a given system has the effect of quadrupling the pressure, and halving it quarters the pressure.

The pressure loss within equipment containing complex air paths is difficult to estimate, so requires experience of similar systems. For ductwork, it is a well-researched subject with pressure charts and loss factors for each element in the system.

Static Pressure is the pressure exerted on duct walls and corresponds to potential energy. Velocity Pressure is the flow pressure and corresponds to kinetic energy. The sum of the two is Total Pressure and corresponds to the total energy increase provided by the fan.

Static Pressure loss is estimated by calculating the Velocity Pressure through each component in the ductwork system and multiplying it by a constant, known as a ‘k’ factor for that component, to provide an estimate of the component Static Pressure. The System Static Pressure is then the sum of all component Static Pressures, and the Velocity Pressure is calculated from the discharge air velocity.

By knowing the System Operating Point, it is possible to plot a System Characteristic curve from which the performance of any fan on that system can be estimated.

Useful Formulae:

Conversion Factors

1 cfm = 1.7m³/h

1litre/s = 3.6m³/h

1m³/s = 3600m³/h

1 mmWG = 9.81Pascals

1inWG = 249Pascals

1mBar = 100Pascals

Note: 1Pascal = 1N/m³

Heat Extraction

Volume flow rate m³/h = (3000 x W)/Δt

W = Power Loss (kW)

Δt = Temp. Rise (K) from inlet to discharge

Heat Radiation

W = C x A x T

W = Power Loss

C = Coefficient of heat transfer (6 for steel)

A = Surface area of enclosure

T = Temp. difference in/out

Fume Cupboard Air Velocities

(Very general guide. Observe the specification)

At sash test height > 0.50m/s Sash test height = 500mm

In-duct ≈ 6m/s

At stack discharge ≈ 10m/s

Fan Laws

V ∝ N P ∝ N² K ∝ N³ P ∝ I K ∝ I

V = Air Volume Flow Rate

N = Rotational Speed

P = Pressure

K = Absorbed Power

I = Air Density

Pressure

Pv(Pascals) = 1/2pv² or 0.6v²

For Air P= 1.2kg/m³ & V= velocity(m/s)

General Ventilation:

Recommended Air Changes per hour for location:-

Storage = 2

Library = 3

Lab = 5

Bar = 7

Workshop = 8

Café = 10

Kitchen = 25

Paint Shop = 50

When selecting a fan, the engineer will need several key pieces of information to establish the requirements of the application and provide a solution accordingly. One such characteristic is the duty point. For example, what is the air volume flow rate required and what is the pressure loss of the system?

Units of Measurement

The volume of air required is typically measure in meters cubed per hour (m³/hr), sometimes this could be swapped for litres per second (l/s) when discussing a small fan unit.

Air pressure is usually measured in Pascals (Pa).

Air Pressure Considerations

When considering air pressure within a fan system it is normally with consideration to both the static pressure (Ps) and velocity pressure (Pv), to provide total pressure (Pt).

Pt = Ps + Pv

Ps or Static pressure can be said, when considering fan engineering, to be the difference between the atmospheric pressure and the absolute pressure at the point under review.

Or

Ps = Pa – Po

Where Po is the barometric pressure, in the order of 100,000Pa.

And Pa is the absolute pressure, both can be measured using an instrument e.g. a barometer.

When calculating static pressure, it is normal to consider air as incompressible fluid, because the pressure under consideration are relatively low, circa sub 2000Pa. When static pressures are above 5000Pa the errors due to compressibility of air become significant.

Pv or Velocity pressure is related to the density of the air and its velocity as is expressed as follows:

Pv = ½ pv ²

Definition of Air Volume & Air Pressure

Air Volume = The amount of space that the air occupies.

Air Pressure = The amount of force exerted by the air or weight of the air molecules.

Air Volume Flow Rate = The volume of air that passes through the fan, duct, or system over a unit of time – the speed of the air.

System Pressure Loss = The decrease in air pressure within the air movement system that is relative to an increase in the air flow rate.