January 2, 2014 at 3:48 pm #132213Virginia WhelanParticipant
My client (a museum) is looking to purchase a UV (µW/lumen) and Visible light data logger with a remote downloading capability. We want to be able to download the data without entering the exhibit area. I have found the Hanwell 4000Lux/UV monitors which seems to fit the bill (but I always feel as if there is another type that I haven’t found that might be better). If anyone has used this particular brand of data logger would you be willing to share your observations on its performance?
Does anyone have any other brand recommendations?
Finally, is there a data logger that monitors UV light (µW/lumen)/ Visible light / RH/ Temp AND has remote downloading capability??? or is that a pipe dream?
thanks for your help and suggestions.
January 2, 2014 at 6:43 pm #132219Elizabeth JablonskiParticipant
This Conserve-O-gram from the National Park Service might help:
January 6, 2014 at 11:55 am #132218Abigail KabakerMember
While I have no experience with them, Eltek seems to make an all in one model. http://www.eltekdataloggers.co.uk/transmitters/light_and_uv.html#tabs-models
January 22, 2014 at 2:52 pm #132217AnonymousInactive
We bought the data logger ELSEC a year ago and are pleased with it. easy to download the information. It just does light – not rH or temp. We purchased ours from Gaylord, but it is available from other vendors. You might check IPI for additional information on monitory humidity and temperature. https://www.imagepermanenceinstitute.org/environmental/pem2-datalogger
January 23, 2014 at 11:47 am #132216
January 23, 2014 at 2:51 pm #132215Scott RosenfeldMember
The Environmental Monitor Type 765 monitors all four parameters, (µW/lumen)/ Visible light / RH/ Temp, but does not have remote downloading capability.
I wonder why your client needs logging of µW/lumen over an extended period of time? The beauty of the µW/lumen metric is that if an initial UV reading is reasonably low (>75 µW/lumen is a common museum standard) then measuring visible light (illuminance) alone might be enough to manage risk. In other words, the quantity of UV is (reduced) in proportion to illuminance. This means if you are meeting your illuminance targets (typically 50-200lux — depending on the material) then UV might not need to be measured over time, at least for filtered artificial lighting sources like HID and florescent. Is there a concern that the filters won’t hold up or won’t be replaced?
I am less familiar with the variations of UV output in filtered daylight over time; if anyone has experience with measuring UV in daylight I would be grateful for more information. I have an Elsec Environmental Monitor Type 765 as well as a spectrometer that measures radiation down to 200nm and I will run some daylight tests if I can find the time.
Lastly, I am unclear what the Elsec and other environmental meters are exactly measuring when it comes to UV? I am sure they do a good job of determining if UV is a problem, but I am skeptical if the numeric values are particularly accurate. According to the Elsec’s cut sheet, their meter measures UV between 300 and 400 nm with an accuracy of 15%. If anyone has more information about this, I would be grateful to know more about how these meters actually measure and what bandwidths of particular lighting sources I need to be concerned about.
January 27, 2014 at 4:24 am #132214Les KacevMember
Scott Rosenfeld is correct. The Elsec 765 is an excellent choice and is widely used by museums.
I would urge all working in the lighting field to ensure they have a good understanding of what their objectives are before determining what meter or datalogger to buy or recommend. A few general comments may help.
1. Broad range products are seldom accurate. I would suggest separate devices for UV, VIS and IR measurements.
2. With the coming of age of solid state lighting [LED] lighting, it is critical that museums have the ability to define what they are looking for and then determine if the lights they consider for purchase meet their specs. One simply cannot rely on manufacturers’ recommendations or specs. Too many institutions unknowingly purchase unsuitable products because their objectives are not defined and because of reliance upon salesmen or even scientists who pose as “experts” but who really are not LED specialists. I urge all to read Druzik and Michalski’s article on museum lighting.
3. There are many characteristics to consider in selecting LED lighting. I will mention just a few. Spectrum, location relative to the Planckian locus in one of the CIE chromaticity diagrams, correlated color temperature [CCT], color rendering index [enhanced CRI from R1 through R15], purity and many more. To measure these one needs a spectrometer. Today one can purchase a hand held spectrometer like the Lighting Passport for under $2000 which can measure all the critical parameters you need to make a rational decision.
4. It is important to understand that all filter based meters and tristimulus meters use VLamda as a basis. VLamda was determined by the CIE in 1924 and is no longer accurate for measuring light and especially LED lamps and luminaires. It is lacking in the blue/green and the red range.
5. Understanding 1 to 4 above makes the choice of a datalogger for continuous measurement a science rather than an art. In general, spectrometer based units are much more accurate than filter based units, but they are also more expensive.
Education is the key to implementing and monitoring museum lighting.
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