Myron L 6Psi and 4P - Manual (Page 52)

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XXVI. ADDENDUM: NEW ORP PPM FREE ChLORINE FEATURE
For 6Psi ONLy Software V.3.51 and later (see pg. 46).
Contact the Myron L Company for more information:
www.myronl.com
*Given water is sanitized by only chlorine at a pH of 5-9 and a temperature of 20-30ºC
A convenient new feature has been added to the Ultrameter II 6Psi
™
that allows the user to choose between ORP millivolts (mV) and parts per
million (ppm) free chlorine readings. mV and ppm free chlorine are the two
most commonly used sanitizer measurement units used in water quality
management. The 6Psi mV to ppm free chlorine conversion algorithm is
based on a published conversion curve that assumes a pH of 5-9 and a
temperature of 20-30ºC in water sanitized by chlorine only and bench testing
performed at the Myron L Company. We have increased the accuracy of low-
range ppm free chlorine readings by extrapolating from the published data.
With this new feature the 6Psi can measure a dynamic range of sanitizer
concentrations that is wider than the range of a colorimetric test kit.
Plot Showing the Conversion Curve between ppm and mV*
Additional ORP Specifications
Spec Value
Ranges ± 999 mV
0.20 – 9.99 ppm
Resolution mV resolution: 1 mV
ppm resolution: 0.01 ppm
Accuracy ± 1 mV
± 2.5% of reading ppm*
8
10
6
4
2
0
0 100 200 600 500 400 300 700 800
ORP (mV)
ORP
(ppm
free
chlorine)
ORP mV to ppm Conversion Curve