This was my e-mail
This meter is going to be way off. Seawater is not NaCl, it is seawater. Calibration
solutions need to be 53 mS= 35 ppt NSW salinity. A 35 ppt NaCl Salinity calibration
solution will only yield a seawater Salinity of 32.5 ppt NSW Salinity. That means that if
one takes your meter and it reads 35 ppt it is off around +2 points low = about 32.5 ppt
NSW so it needs to read 37.5. This is a nice toy you have but needs some fixing, same with
those tables.
Furthermore, your table is a NSW Density table, set to 59 F.
Density DOES NOT = SG. SG is roughly 1 unit higher, meaning D = 1.023, then SG = 1.024. I
have a Excel spread sheet program that lets me calculate such tables, based on seawater
stds. And all this depends on what the SG meter is calibrated to.
The std solution of a meter for testing seawater is, 32.4536 g/Kg, which = 53,065 uS @25C
or 53 mS. If it is for
SG it is different, if it is for a refract it is different. The only solution that meets
all NSW readings, be it conductivity @53,065 uS (53mS), @ 1.0269 SG,
Refract @ 3.5% or 35 ppt is a real std seawater solution. Such solutions are
available only in one place and cost about $$$ for a 5 l bottle
http://www.seawater.com
The std equation of state for seawater is
K15 = Conductivity of seawater sample / conductivity of std KCl solution @ 15 C 1 ATM and
the KCl being at 32.4356gkg
S = 0.0080 - .1692 K15 exp 1/2 + 25.3851 K15 + 14.0941 K15 exp 3/2 - 7.0261 K15 ² + 2.7081
K15 exp 5/2
If the conductivity of the sample is 53, 065 uS and it is the same for the KCL, then K15
=1. If you plug that 1 into the equation it = 35 ppt
Have them look at these
http://www.start.or.th/got/data/techsupp/pss78.htm
http://www.es.flinders.edu.au/~matto...lecture03.html
http://gaea.es.flinders.edu.au/~matt...es/salcon.html
Reef Aquarium Salinity: Homemade Calibration Standards
http://reefkeeping.com/issues/2004-06/rhf/index.htm
--
Boomer
If You See Me Running You Better Catch-Up
Former US Army Bomb Technician (EOD)
Member; IABTI, NATEODA, WEODF, ISEE & IPS
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