Milwaukee ma887 temperature inaccuracy used to calculate salinity

[glweek]

Accurate salinity is measured by accurate temperature. So with the ma887 The temperature of the sample is always way off because the steal ring around the the testing eye sucks the temperature out of the small sample before it can warm the plate to the correct water temperature thus giving an inaccurate salinity reading; no?

 

[Cory]

Yes its probably not the intended temp then. Id double check with a refractometer eyelense type.

 

[cmcoker]

That unit says it has automatic temperature compensation
From their website:
"The MA887 refractometer is an optical device that is simple and quick to use. Samples are measured after a simple user calibration with distilled or deionized water. Within seconds, the refractive index and temperature are measured and converted into one of three popular measurement units"

 

[glweek]

I get how the optics work which is why im so confused. if calibrated with room temp RO water at say 70* and the tank sample after sitting in the disc for a few seconds only raises the indicated temp to 70.7 then the reading is taken off of that wouldn't it be calculating the salinity off of that 70.7 temp? It can't just magically know what temperature the sample is other than its indicated reading in order to calculate the correct numbers. and again even if using RO at X temp how does the plate know the actual temp of the fluid with the metal disc again sucking the temp out of the sample?

 

[cmcoker]

The temperature of the sample is compensated in the reading, even if it has dropped to match the metal plate. It's the same with handheld refractometer, if there is an automatic temperature compensation feature then the temperature won't matter. It is being taken into account.

In this article, Randy talks about temperature differences when using a hydrometer that is calibrated at a certain temperature. http://www.reefkeeping.com/issues/2004-07/rhf/

The image is from that article, so it shows how it's not magic. In the case of the ma887, There is an algorithm programmed onto the digital refractometer that says at X refractive index and Y temperature the specific gravity is Z.