Vibration calibrator constant up to a maximum specified weight of test object. Older models can be used to calibrate objects weighing up to a maximum of approximately 100 g, whereas the latest instruments can work stably with test objects weighing over 500 g. Vibration calibrators are most often used for testing and checking vibration sensors and measuring instruments at the site of their operation and are, therefore, usually transportable and battery operated. The most commonly occurring vibration frequency of calibrators is 159.2 Hz, which is equivalent to a radian frequency of 1000 rad/s. The vibration displacement, velocity and acceleration of sinusoidal signals
Mole (unit) in chemistry as a convenient way to express amounts of reactants and products of chemical reactions. For example, the chemical equation can be interpreted to mean that 2 mol dihydrogen (H) and 1 mol dioxygen (O) react to form 2 mol water (HO). The mole may also be used to represent the number of atoms, ions, or other entities in a given sample of a substance. The concentration of a solution is commonly expressed by its molarity, defined as the amount of dissolved substance per unit volume of solution, for which the unit typically used is moles per litre (mol/l).