Accusonic 8510+ series Reference Manual page 24

Flow Computation 3-7
The Calculated Temperature is:
Temperature F = 1.129  10  c  1.46827  10  c + 6.450118  c  9559.7 + Temp Correction
-7 3 -3 2
Temperature C = 5.0822  10  c  2.127056  10  c + 29.88592  c  14096 + Temp Correction
-6 3 -2 2
where c is the average speed of sound in water, and Temp Correction is a Section Parameter.
These formulae apply only to fresh water at low pressure.
At 10 Bar Pressure:
The flowmeter will indicate 0.6F (0.3C) high at near freezing, and 1.4F (0.8C) high at 90F (30C).
At a Salinity of Sea Water (35 Parts / Thousand):
The flowmeter will indicate 19F (10C) high at near freezing, and 30F (17C) high at 90F (30C).