Laboratory instruments help conduct reliable tests. Pipettes and pipetters dispense specific amounts of liquid to ensure accurate volume measurements. Viscometers measure the viscosity of fluids. Refractometers measure the specific gravity of liquids. Gas analyzers measure the concentration of various gas emissions. Polarimeters measure angle rotations of polarized light. Films and seals are added to labware to protect samples and prevent evaporation. Lab aspirator pumps help to safely dispose of dangerous pathogens, critical liquids, and any class III or IV biohazard in a self-contained waste collection system. Lab Penetrometers measure the density of items such as food and pharmaceutical products, or soil in agriculture and geology.