[SEL] reducing noise on portable generator

Listerdiesel listerdiesel at gmail.com
Wed May 18 10:12:45 PDT 2005


On 5/18/05, Roger DiRuscio <solarrog at pacbell.net> wrote:
> Yes this is possible, but The rule of thumb is 2 hp per kilowatt at 3600 RPM
> and 4 HP per kilowatt at 1800 rpm. The losses are large
> and yes there is some wiggle room
> 

When we used to build silenced generators for the film & TV
industries, we made up sound deadening panels from a steel tray,
filled with rockwool, covered in polythene and then covered with
perforated steel or ali sheet.

It is also possible to get lead sheet bonded with foam that is almost
as good and slightly lighter.

The aim is to absorb the sound and stop it reflecting out from the
source off nearby objects.

One of the most difficult things we had to silence was the cooling fan
on one of the 50kW gennies. This had a particularly noisy whine which
we had a lot of trouble getting rid of as it was placed adjacent to a
join in two of the panels. In the end we made an internal mini-cover
that sat across the fan opening and took out the worst of the noise,
allowing the main covers to do the rest.

High frequencies tend to be noticed more than low, and I think we got
down to 3dbA at 3metres or about 10 feet, mainly in the sub-50hz
frequencies from the cabinet itself vibrating from the engine
movement.

The larger sets had labrynth air passages in the doors to allow
cooling air in and out.

A simple U shaped cover with sound-deadening material inside should
work well, but you'd need to experiment with placing of the cover with
respect to the engine cooling fan and the place of most noise
emission.

Peter
-- 
Peter A Forbes
Email: listerdiesel at gmail.com
Web: www.oldengine.org/members/diesel




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