Clean­rooms have partic­ular require­ments when it comes to their venti­lation systems. These require­ments include suffi­cient air throughput and pres­sure, precise control of temper­a­ture and humidity, as well as a constant air purity achieved by filtering out even the smallest impu­ri­ties. Filter-fan-units (FFU) designed for ceiling instal­la­tion combine filter tech­nology and state-of-the-art fans, enabling them to meet these require­ments to optimum effect.

As the “heart” of the FFU, fans play an impor­tant role in clean­room tech­nology. The latest gener­a­tion of RadiPac EC centrifugal fans from ebm-papst are there­fore specially designed for this area of appli­ca­tion. Not only do they supply the air volumes of up to 2,330 m³/h that are stan­dard for the various FFU sizes, with suffi­cient pres­sure reserves for recir­cu­lated air oper­a­tion in clean­rooms, but they also have effi­ciency levels of over 60% thanks to EC tech­nology and the latest gener­a­tion of RadiPac impellers. Compared to the previous industry stan­dard, this means a 10% reduc­tion in power consump­tion. They are also 6 to 7 dB quieter than the commer­cial stan­dard and so easily meet the strict noise protec­tion require­ments for produc­tion in clean­rooms.

(Image | ebm-papst)

Aero­dy­nam­i­cally opti­mized impeller

The impeller with its five geomet­ri­cally sophis­ti­cated impeller blades and devel­oped according to the latest aero­dy­namic find­ings, plays an impor­tant role in this opti­miza­tion. This blade geom­etry dras­ti­cally reduces flow losses. The inlet ring was also designed for perfect inter­ac­tion with the new impeller. The sophis­ti­cated impeller geom­etry not only reduces flow losses, but also noise gener­a­tion.

EC motors: more powerful, more flex­ible and even more compact

The driving force behind the new RadiPac centrifugal fans are high-effi­ciency EC motors in the 170 to 500 W power range. Committed to system effi­ciency, the drive system consisting of motor and inte­grated power elec­tronics is indi­vid­u­ally adapted to each fan and opti­mized for the respec­tive oper­ating range. The design and func­tion­ality have also been updated to the latest gener­a­tion and a MODBUS inter­face with DCI addressing has been added. An inte­grated reso­nance sensor will also be avail­able as an option in future. This reso­nance sensor measures oscil­la­tions and vibra­tions in real time and can there­fore detect imbal­ance caused by dirt, for example, and then send a message before the fan is damaged.

Fast commis­sioning – MODBUS RTU with auto addressing

The air supply in a clean­room is not usually a stand­alone solu­tion. Instead, it is inte­grated into the entire automa­tion process and its PLC and SCADA systems. Just like all other sensor and actu­ator infor­ma­tion, the fans of the FFUs have to be inte­grated into the system network, and their status infor­ma­tion must be provided to the controls and visu­al­iza­tion systems. The initial commis­sioning of a clean­room system requires a signif­i­cant output of time and money. Based on user reports, the time required to manu­ally connect an FFU data point is around five to ten minutes. The more fans there are in use, the more poten­tial there is to make savings. An addi­tional acces­sory can help as a first step: Connector panels for bus and power distri­b­u­tion, which can be used to connect up to 64 fans in series per channel. In addi­tion, the new RadiPac fans are not only avail­able with a digital ebmBus or MODBUS-RTU inter­face, but also with auto addressing, which signif­i­cantly reduces commis­sioning costs.

Connector panels for bus and power distri­b­u­tion, …

… which can be used to connect up to 64 fans in series per channel. (Images | ebm-papst)

A master/slave-based bus always requires unique slave addresses. The fans are usually deliv­ered with an address that is preset in the factory, which is always the same (e.g. slave ID = 1). There­fore, the addresses must be assigned a unique address during commis­sioning for oper­a­tion in the network group, prefer­ably in the order of the MODBUS cabling. This time-consuming process is now auto­mated by what is known as DCI (daisy chain inter­face) addressing, which signif­i­cantly reduces the time required for commis­sioning.

DCI addressing using MODBUS/DCI as an example – How it works

A fan equipped with a DCI is addressed by a hard­ware signal (15 V/24 VDC) via an “Init pin” on the RJ45 network plug, and thus temporarily assigned the slave address 247. Only the unit acti­vated in this manner “listens” to messages sent to this DCI address 247 and accepts a new MODBUS address sent from the master to this slave. Once this fan has been success­fully re-addressed, its DCI relay is switched on and the “Init pin” (15 V / 24 VDC) is switched to the next fan module in the chain. This fan is now acti­vated via the hard­ware signal (“Init pin”) and the addressing continues as described above. If the cable diagram is known, the posi­tion of the fan unit in the clean­room ceiling can be deter­mined via the cable routing. Manual assign­ment of the fan address to the instal­la­tion loca­tion is no longer neces­sary; the master controller takes over the complete addressing and local­iza­tion of the fans installed in the FFUs in the clean­room ceiling. There is a signif­i­cant reduc­tion in the time and costs of commis­sioning.

The right acces­sories are crucial

Good impellers are always sensi­tive on the intake side. If faults occur here, they are often unable to fully exploit their advan­tages. Reasons for this include ceiling designs that only allow lateral intake, and pre-filter boxes or mounted coolers that obstruct the inflow. This is where the right equip­ment, tailored to the impellers and incor­po­rating many years of expe­ri­ence in venti­lation appli­ca­tions, can help. After all, with fans it is always impor­tant to be aware of the system concept and the appli­ca­tion-specific envi­ron­ment. One example is the closed Flow­Grid air inlet grill. This acts as a kind of recti­fier that reduces noise-gener­ating turbu­lence in the inflow without changing the air perfor­mance or power consump­tion. The fans are then even quieter, which bene­fits venti­lation appli­ca­tions as well as many others. However, it can also be used as contact protec­tion by clip­ping in an addi­tional guard grill inlay.

(Image | ebm-papst)

The fans are avail­able both as a complete plug & play unit and as indi­vidual compo­nents, allowing users to combine the impellers with their own solu­tions. With an instal­la­tion depth of 190 to 275 mm and diam­e­ters of 280, 355 and 400 mm, complete devices are very compact, meaning they can be easily accom­mo­dated even in tight instal­la­tion spaces and are there­fore also suit­able for retrofit appli­ca­tions. They meet all the regu­la­tions required for clean­room use, thereby providing users with assur­ance for use world­wide, both in Europe and North America as well as in the Asian market.