Determining and Monitoring Densities of Non-Porous Solids
Cargille Heavy Liquids are precision calibrated density liquids used to determine the density of non-porous solids. A specimen that sinks is obviously greater in density than the liquid; conversely, a sample that floats is lower in density. Density is determined by successively swirling a specimen in different Heavy Liquids until one is found in which it remains suspended. The density of the sample then matches the density of the Heavy Liquid, which is a known value.
Cargille Heavy Liquids have applications in Geology, Mineralogy and Gemology for sorting and identification, e.g. gems, selected intervals of density will separate classes or individual specimens. For Quality Control, one liquid may suffice to test for maximum or minimum density of plastics, insulation, ceramics, and many other compressed items. In instrumentation, Heavy Liquids have utility as manometer liquids and control components.
Cargille Heavy Liquids are available in a range extending from 0.8 to 3.31 gm/cc. The Liquids are divided into two Series: Aqueous and Organic. The Aqueous Series, consisting of Inorganic Salts, is water soluble and employed when water insoluble materials are involved. The Organic Series is miscible with most organic solvents and used with water soluble materials.
Heavy Liquids are formulated to a specifically requested density standardized at 23°C and to a tolerance of ±0.005 gm/cc (refer to Tolerance and Temperature Sections).
How to Order Heavy Liquids
- Determine if object to be immersed in Heavy Liquid is soluble in a water solution or an organic solvent. If it is water soluble, a Heavy Liquid from the Organic Series is recommended; if soluble in an organic solvent, select from the Aqueous Series.
- From the Heavy Liquid Selection Guide, find the density required under the appropriate Series within the density range indicated.
- Order by Catalog Number and specify the precise density of Heavy Liquid required.
- Specify if a tolerance of ±0.0005 gm/cc is required. A ±0.005 gm/cc tolerance is supplied when no tolerance is specified.
- Specify if calibration to a temperature other than 23°C is required. When no standardization temperature is specified, Heavy Liquids are supplied calibrated to 23°C.
- Specify the quantity of each Heavy Liquid required (refer to Packaging Section).
Supplied adjusted to a tolerance of ±0.005 gm/cc or ±0.0005 gm/cc. The ±0.005 tolerance is the most widely used and has proven satisfactory for most applications; it is supplied when no tolerance is specified. The ±0.0005 tolerance is supplied upon request and subject to a Tolerance Charge as listed under “Adjustment Charges” in price schedule.
All Heavy Liquids are standardized at 23°C; their densities are inversely related to temperature. Inaccuracies in measurement can result if used at temperatures other than 23°C. For specialized applications, Heavy Liquids will be calibrated to another temperature for a modest additional charge. Refer to “Temperature Charge” listed under Adjustment Charges in price schedule.
Readjusting Heavy Liquids
When used infrequently and for short durations, Heavy Liquids will remain stable. Depending upon frequency of use, changes from evaporation or solvent dilution may occur which warrant adjustments.
The Organic Series is readjusted by adding higher or lower Organic Series Liquids (see price sheet for appropriate liquid). The Aqueous Series is readjusted by either: adding distilled water, or preferably, an Aqueous Series Liquid from the same basic Group.
Readjusting Heavy Liquids With Sink Floats
Heavy Liquids may be checked for density by the Pycnometer method or other acceptable techniques. For simplicity and speed, readjustments may be performed by use of Cargille Sink-Float Standards. The method is easily learned by technical as well as non-technical personnel and has a high degree of accuracy and reliability.
A Sink-Float Standard is a weighted, hermetically sealed, boro silicate glass capsule having a specific density. Sink-Float Standards are available in a density range from 0.70 to 7.50 gm/cc and calibrated at 23°C to correspond to the Heavy Liquids. Each Standard is permanently marked with its density. Sink-Float Standards immediately alert the user to a change in Heavy Liquid density due to evaporation, dilution or temperature drift by whether they sink, float or swim in the Liquid. If the density of the Liquid is greater than the value specified on the Sink-Float Standard, the Sink-Float will float; if the density is less, the Sink-Float will sink. A perfect match in density and temperature is attained when the Sink-Float Standard is suspended or swims in the Heavy Liquid. For complete information on applications, and procedures refer to Sink-Floats. [add link to Sink-Floats data page]