Specific gravity balance

The Westphal specific gravity balance is a device that will measure the specific gravity directly if water is one of the liquids. It applies two concepts ... 

There are other methods for the determination of density. These include the specific gravity balance and the use of a pycnometer (weighing bottle). 

Arthur H. Thomas Hydrometer for Liquids Lighter than Water Westphal Specific Gravity Balance Pycnometer Specific Gravity Bottle Lypkin Pycnometer... 

The specific gravity balance may be used to monitor change within a settling suspension (7, 8). Such a balance comprises two bobs, one in clear fluid and the other in the suspension being studied. The bobs are connected to the two arms of a beam balance. The depth of immersion of the bobs is adjustable. The change in buoyancy is counterbalanced by means of solenoids that are connected to a pen recorder. From the settling behavior as monitored by the trace of pen recorder, the particle size distribution can be calculated. 

Because density is often used as a quality control check, particularly on batches of rubber compound, there has been a necessity to make measurements essentially in accordance with standards such as ISO 2781 but making the determinations as rapidly as possible. Hence various designs of "specific gravity balance" arc in existence, primarily intended for rubbers, which to varying degrees automate the process. In one form of apparatus, the practical steps of weighing in air and water are taken, but the result may then be read directly from a scale calibrated in density. Completely automatic apparatus have also been produced. 

Suito specific gravity balance p-Back-scattering... 

Specific gravity or API gravity is measured by means of hydrometers (D287), pycnometers (D941 and D1217), or the chainomatic specific-gravity balance if very many small samples (16 cc) must be tested. For viscous oils or semisolid bitumens, a pycnometer (D70) or weighing bottle may be used, for solids an analytical balance (D71) equipped with a pan straddle. 

---