## Adam Equipment: PW Analytical Balances

By | July 15 2011

PW Analytical Balances provide users with an accurate and consistent tool for density determination of different materials. The PW contains built-in software application that walks users through the process, then calculates and displays the density result.

Density, or specific gravity, can be a critical property of a material. Density determination, often performed by scientists and engineers, is helpful in many industries to identify unknown materials, to verify the purity of a given substance, or to reveal information about the concentration of solutions. The PW balance is also used to verify the integrity of a sample. For example, molded parts are often tested to ensure their density is within an acceptable tolerance. Deviation from the spec may indicate the formulation is incorrect or the sample contains air pockets, which could affect product performance.

The PW balance utilizes the principles of buoyancy to determine density. It follows the formal Archimedes Principle: “An object partially or wholly immersed in a liquid is buoyed by a force equal to the weight of the liquid displaced by the object.”

On the PW, density software guides users through the procedure to determine the density of solids or liquids. It allows adjustments for temperature and for the liquid type that is used in Adam’s DDK Density Determination Kit. Typically, water is used to test the substance’s density. If the user substitutes a different liquid, the user can adjust it in the software.

• Suspended weighing cradle to replace the standard pan
• Independent support for the beaker of fluid
• Glass beaker
• Thermometer with clip for suspension in the fluid
• Glass sinker of known volume for determination of fluid density

Users place the density determination kit above the weighing pan on the balance and enter the density determination mode using the balance keypad. The sample is weighed dry in air and the weight is entered into the balance with the simple press of a button. Next, the sample is suspended in the liquid so it is fully submerged. The user enters that weight, and the balance calculates and displays the density.

If the user needs to determine liquid density, that’s where the glass sinker comes into play. Fill the beaker with the liquid to be tested, suspend the glass sinker on the DDK stand, and the balance calculates the density.

PW offers three models with readability of 0.0001g and maximum capacities from 120g to 250g. Sixteen units of measurement include one custom unit. Other features include die-cast aluminum housing with glass weighing chamber, bi-directional RS-232 interface and backlit LCD display with dual digits and capacity tracker.

The PW makes density determination an easy and fast process because it performs most of the work; users just put the sample on the cradle. With Adam’s PW balance and DDK, testing samples becomes simple, accurate and fast work.

Archimedes was a Greek mathematician and engineer who developed his principle when researching the purity of the gold used in King Hiero’s crown, which came into question when the king’s goldsmith was rumored to be preparing crowns with a cheaper alloy, using a silver-gold mixture instead of pure gold.

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July 2011

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