Fan in which the air enters the impeller with an essentially axial direction and leaves it in a direction perpendicular to the axis. Ref. UNI EN ISO 13349:2009. Definition of the fans, their direction of rotation, the conventional designation of the position of the outlet of a centrifugal fan and the construction arrangements and motor positions with respect to the fan are all de ned in UNI ISO 13349:2009 (“Vocabulary and de nitions of categories”) (in replacement of UNI7972:1980). The standard provides the following definitions:

• TYPE A INSTALLATION: installation with free inlet and outlet (ISO 5801 and ISO 5802).
• TYPE B INSTALLATION: installation with free inlet and ducted outlet (ISO 5801 and ISO 5802).
• TYPE C INSTALLATION: installation with ducted inlet and free outlet (ISO 5801 and ISO 5802).
• TYPE D INSTALLATION: installation with ducted inlet and ducted outlet (ISO 5801 and ISO 5802).

Standard fans are suitable for type D configuration; the purchase of a type D fan implies that the customer is required to make connections to ducting and/or machinery on both the inlet and outlet sides, and said connections must comply with the prescriptions of UNI EN ISO12499-2009 section 7.1.
The use of the fan in different configurations must be specified at the time of the order.
AERTECH SRL can supply suitable accessories for alternative configurations. Standard fans comply with the “machinery directive” 2006/42/EC, in relation to which they are defined as “partly completed machines”, art. 2 section g, and they are in compliance with article 13.
Each complete fan is followed by the issue of a declaration of incorporation ex Annex II part 1, section B.
With regard to safety requirements for mechanical guards, standard fans comply with UNI EN ISO12499-2009.
The performance curves were calculated by performing tests on fans in compliance with ISO 5801:2007 “Test methods and terms of acceptance” (which replaces UNI 10531:1995 and complies with UNI EN ISO 5801:2009).
To carry out the tests the fans were installed in compliance with the requirements for category A: with free inlet and outlet connected to the test station. Measurement of the sound power level was carried out in compliance with UNI EN ISO 3746: 1997 (Survey method using an enveloping measurement surface over a reflecting plane).
The measurements were subjected to corrections to take account of background noise and ambient reverberation levels.
All impellers are statically and dynamically balanced in compliance with the requirements of ISO1940/1:1993 “Requirements of the balancing of rigid rotors”. The fan test procedure involves a functional check, which consists of a running test with consequent evaluation of mechanical vibration pursuant to ISO14694:2003.