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
Per cent mille because reactivity values tend to be small, so measuring in pcm allows reactivity to be expressed using whole numbers. Per cent mille A per cent mille or pcm is one one-thousandth of a percent. It can be thought of as a "milli-percent". It is commonly used in nuclear reactor engineering as a unit of reactivity. In nuclear reactor engineering, a per cent mille is equal to one-thousandth of a percent of the reactivity, denoted by Greek lowercase letter rho. Reactivity is a dimensionless unit representing a departure from criticality, calculated by: where k denotes the effective multiplication factor for the