UV monitors

Peter Lundskow <plundskow [at] dnr__state__in__us> writes

>I have a question that I have been researching and have not been
>able to find an answer to.  I know when it comes to general
>recommended UV readings for museums 10 microwatts per lumen is
>optimum with 75 microwatts per lumen being the high end of the
>'safe' range.  Also, that many museums use the Crawford type 760 UV
>monitor.
> ...
>Recently, we purchased a more accurate meter, the UVX Radiometer
>from UVP Ultra-Violet Products (this meter comes with certification
>of calibration)it takes readings in microwatts per cm squared.  I
>have not been able to find any information on how to convert one
>measurement to the other and what safe readings would be for museums
>when measured in microwatts per cm squared. Also, I would mention
>our new meter has two sensor heads, one in the 250nm range and the
>other in the 360nm range.  I have been told by the same source that
>readings with both sensors are needed to get a more complete picture
>of UV exposure.

Running these measurements through the internet measurement
converter, <URL:http://www.convertit.com/go/entisoft/> gave the
following results:

    Conversion Result:

        10 microwatt/lumen (reciprocal of luminous efficacy)
        TO microwatt/centimeter^2 (heat flux density)

            = 0.001 1/lux (reciprocal of illuminance)

or,

        1 microwatt/centimeter^2 (heat flux density)
        TO microwatt/lumen (reciprocal of luminous efficacy)

            = 10000 lux (illuminance)

They can provide more advice than myself on how to practically apply
and understand the conversion.

Neill McManus
Conservator
Jewish National and University Library
Jerusalem


                                  ***
                  Conservation DistList Instance 17:17
                  Distributed: Thursday, July 31, 2003
                       Message Id: cdl-17-17-002
                                  ***