339 research outputs found
A methodology to measure the acoustic performance of access floors
No full textThe European standard EN ISO 140-12:2000 gives a methodology to measure the acoustic performance of access floors in terms of both airborne and impact sound insulation.
Access floors are often used in office buildings and working environments as they create a hollow space below the floor surface for network cabling and electrical wiring: in this way they are useful from the functional (ease of inspection, repair and changing of system elements), the aesthetic (no exposed wires and elements) and acoustic point of view.
This paper presents the measurement procedures used at the Acoustic Laboratory of the University of Perugia – Italy, in order to perform the tests defined by the EN ISO 140-12.
The standard requires the measurement of two parameters, Ln,f e Dn,f , that qualify respectively the airborne and the impact sound insulation trough an access floor, and the calculation of the two corresponding single number indexes Ln,f,W e Dn,f,W.
A sample of access floor has been tested in the purposely prepared reverberating rooms of the Laboratory, with and without covering.
Particular attention has been paid to test rooms set up and to sample installation because of the complexity of these phases
Una metodologia per la misura delle prestazioni acustiche di pavimenti sopraelevati
No full textLa normativa UNI EN ISO 140-12:2001 fornisce una metodologia di misura atta a valutare le prestazioni acustiche di pavimenti sopraelevati in termini di abbattimento del rumore aereo e di calpestio tra due ambienti confinanti. I pavimenti sopraelevati sono spesso utilizzati negli allestimenti di uffici e centri direzionali poiché consentono di creare al di sotto del piano di calpestio un vano tecnico all’interno del quale far passare le cablature delle diversi reti, risultando di grande utilità dal punto di vista funzionale (facilità di ispezionamento, riparazione e modifiche degli impianti), estetico ed acustico.
In questa memoria vengono riportate le procedure di misura utilizzate presso il Laboratorio di Acustica della Facoltà di Ingegneria di Perugia per l’esecuzione delle prove definite dalla normativa UNI EN ISO 140-12. Tale norma prevede la misura di due parametri, Ln,f e Dn,f , rispettivamente definiti come il livello di pressione sonora di calpestio e l’isolamento acustico alla trasmissione laterale, e il calcolo dei corrispondenti indici unici Ln,f,W e Dn,f,W. Tali grandezze permettono di qualificare le prestazioni acustiche del pavimento, supponendo che la parete divisoria tra i due ambienti di misura sia dotata di un potere fonoisolante superiore a quello del pavimento stesso.
Particolare risalto è dato all’allestimento delle camere di prova e al montaggio dei campioni, essendo queste le fasi più complesse e che maggiormente influenzano i risultati finali
Experimental evaluation of the performances of a H20LiBr absorption refrigerator under different service conditions
No full textThe paper describes an experimental plant aimed at simulating and verifying the performances of a single-stage H2O–LiBr absorption machine. The machine is water cooled and it is supplied by hot water produced by an electrical boiler; it is possible to simulate different service conditions by varying the temperatures and the flow rate of water in the external circuits. Measurement facilities allow to record in real time all the main operating parameters of internal and external circuits (temperatures, pressures and flow rates). The paper illustrates the characteristics of the machine and of the plant and the results of various experimental campaigns. In particular, the acquisitions on the plant have tested different service conditions by varying the flow rate and the temperature of the supplying hot water; the energy and energy performances of the plant are presented and compared with data from literature and from a simulation code developed for the plant.
The results show that the absorption machine can work, with acceptable efficiency, with input temperatures of about 65–70 °C; this result is interesting for a future supply of the machine with solar energy
“Impact sound insulating performance of access floors"
No full textAccess floor are raised floor systems consisting of modular panels supported by posts at a certain height to create a gap below the floor surface. Electrical wires and pipes can be conveniently placed inside the gap in order to avoid exposed installations and to simplify operations involving the inspection, repair, changing or adding of system elements. This paper presents the results of two measurement campaigns carried out using the procedures given by EN ISO 140-6 and 140-12 standards. A stage of measurement has been performed on different access floor configurations, obtained by changing different floor elements, such as panels, surface finishes and damping materials under the posts base, in order to optimize their acoustic performance. Impact sound insulating properties of access floors combined with false ceilings were also tested and are reported in the paper
Caratterizzazione delle emissioni acustiche di trasformatori di energia elettrica di elevata potenza
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