Temperature effects on Hydrometers and Refractometers
By: Gregory S. Taylor
What devices were tested:
Refractometer purchased from Fishwish
Swing arm hydrometer "The Original" SeaTest Specific Gravity Meter
Test 1
Took readings of water ranging in temperature from 28 to 101 degrees F with the devices at room temperature.
Results of Test 1
There was no consistent difference in readings throughout the range tested. Maximum variance was 3 ppt on the refractometer and .0005 on the hydrometer. Between 40 and 90 degrees F variance dropped to 1 ppt on the refractometer and 0 on the hydrometer.
Test 2
Water at 77 degrees F with the devices ranging in temperature from 40 to 103 degrees F. I couldn't lower the refractometer temp any further or the water in the sample would freeze on contact.
Results of Test 2
Readings were effected significantly during the first 5 to 10 seconds, but if I waited 30 seconds the maximum variance was 0 for both devices.
Bottom line
It does not appear that water temperature significantly effects either the
refractometer or swing arm hydrometer. However, it must be noted that Hydrometers
are typically not very accurate at any temperature. The hydrometer I used in
my test, for example, is off by 0.0031, which is an 11% error rate.
If you have any comments,
questions, or recommendations, please email me at greg@saltyzoo.com.
This page last
updated on:
June 23, 2002
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2001 by Gregory S. Taylor. All Rights Reserved. No part of this site may be
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