Salt Solution Specific Gravity Hydrometer – C280215

The C280215 Specific Gravity Hydrometer provides a manual reading of solution density relative to reference water. The laboratory converts that reading into NaCl concentration using reference data with the correct temperature basis. The hydrometer supports ASTM B117 salt-solution checks when used with an appropriate documented procedure.

What the Hydrometer Measures

The numbered stem reports specific gravity, not salt percentage. Specific gravity compares the solution’s density with the known density of pure water at the reference temperature specified for the scale. A reading of 1.03 means the solution is 1.03 times as dense as the reference water; the reading does not mean 3% NaCl.

Measuring and Converting the Result

Place the hydrometer in a suitable cylinder containing enough solution for the glass float to move freely. Allow the hydrometer and solution to reach the same temperature. Keep the hydrometer clear of the cylinder walls, remove attached bubbles, and follow the supplied meniscus-reading instructions.

Measure at the hydrometer’s specified calibration temperature or apply the appropriate correction for the actual sample temperature. Then convert the corrected specific gravity reading into NaCl percent by mass using matching NaCl reference data.

Temperature correction and concentration conversion are separate steps. A standard glass hydrometer does not automatically perform either calculation.

ASTM B117 requires the collected solution to contain 4–6% NaCl by mass. The specific gravity limits used to evaluate that requirement must match the instrument’s temperature basis. There is no universal specific gravity interval for every hydrometer and temperature.

Selection, Care, and Verification

Confirm the measurement range, scale divisions, calibration temperature, and any required calibration certificate before ordering. These details should match your laboratory’s measurement procedure.

Follow appropriate verification checks, rinse and dry the glass after use, and store the hydrometer where the stem is protected from damage. Contamination, attached bubbles, and incorrect temperature correction can affect the calculated salt concentration.

Alternative Methods and Related Supplies

Choose the
Salimeter 11-606 Hydrometer — C280220
for a salt-concentration scale, or the
Salinity Refractometer — C280225
for measurements using a few drops of solution.

Auto Technology also supplies
pre-mixed 5% salt solution — C173300.

View ASTM B117 salt, solution, water, and measurement supplies.