How to calibrate Density Cups? How to measure Density

How to calibrate the pycnometer?

• Clean the glass pycnometer successively with a solution of chromic acid, distilled water and a solvent that evaporates without leaving a residue, and allow it to dry thoroughly. 

• Rinse the metal pycnometer with a solvent that evaporates without leaving a residue, and dry it. Bring the pycnometer to room temperature and weigh it. 

• If very high accuracy is required, the pycnometer should be washed, dried and weighed continuously until the difference between two successive weighings does not exceed 0.5 mg. 

• If higher accuracy is required, it is (23±0.5)"C. At a temperature not exceeding 1"C, fill the pycnometer with distilled water. Stopper or cap the pycnometer leaving the overflow hole open, taking strict care to prevent the formation of air bubbles in the pycnometer. 

• Place the pycnometer in a constant temperature Water Bath or in a constant temperature chamber until the temperature of the bottle and the temperature of the contents of the bottle are constant. 

• Use absorbent material. Wipe up spilled material and dry the exterior of the pycnometer effectively with absorbent material. No more wiping up any spills afterwards. Immediately weigh the pycnometer filled with distilled water to the nearest 0.001% of its mass.

  

Determination of density

1. Replace the distilled water with the sample, and repeat the above steps. Wipe off any sample residues on the outside and wipe with clean absorbent material, allowing to dry completely.

2. Analytical gloves should be worn during operation, and avoid touching the pycnometer directly with hands. Before weighing, the pycnometer should be filled quickly to minimize the mass loss of volatile samples.

3. When the sample is injected into the pycnometer, air bubbles should be prevented. Effectively wipe up spills around the overflow to ensure accurate weighing.