[time-nuts] HP5370 power supply measurements

[Orin Eman]

On Fri, Jul 15, 2016 at 10:55 AM, Poul-Henning Kamp <phk at phk.freebsd.dk>
wrote:

> --------
> In message <
> CANy2iXq6ONvriDoFgNFkEBQjDKntP7t8KuE7BOUpxJWLCuxLsw at mail.gmail.com>
> , "William H. Fite" writes:
> >David Kirkby scripsit:
> >>
> >> I often here of people replacing fans with quiter ones, but I suspect
> that
> >> all they really do is reduce the airflow.
> >
> >Not necessarily, Dave. The Austrian company, Noctua, for one, makes
> >extremely quiet fans with excellent airflow.
>
> ... at zero pressure differential, which is easy to do (Think: ceiling
> fan).
>
>

Right.

You have to look at the curves on the data sheet that shows air flow vs.
static pressure (and be careful about the static pressure scale).  I found
that a 'quiet' fan would often be flowing one tenth as much air as the
original fan at the static pressure at which the original fan was rated.

In a given instrument, you may get away with the quieter fan, but how would
you tell other than putting a thermometer inside and making a before/after
comparison?

Orin.