Vibration Measurement Units

Vibration is the movement or mechanical oscillation about an equilibrium position of a machine or component.

Vibration measurement units.

Va can use the units of displacement velocity and acceleration displayed as a time waveform twf but most commonly the spectrum is used derived from a fast fourier transform of the twf. The vibration spectrum provides important frequency information that can pinpoint the faulty component. The diagram on the previous page showed a typical value for vibration of 1 2 g rms. It can be periodic such as the motion of a pendulum or random such as the movement of a tire on a gravel road.

The vibration parameters are almost universally measured in metric units in accordance with iso requirements these are shown in the table. In north america the velocity unit usually used for linear velocity scales 8 is in s and a commonly used frequency unit is kcpm kilocycles per minute. Psi pascal pa x 1 45 x 10 4. In lb mm n x 0 175.

Acceleration g s rms acceleration in sec2 rms acceleration mm sec2 rms velocity mm s rms velocity mm s peak velocity in s rms velocity in s peak displacement mils peak peak displacement mm peak peak displacement µm peak peak. Kg cm2 psi x 0 0703. When the vibrating object. Pascal psi x 6895.

Units used are inches per second or millimeters per second for velocity or in terms of g or meters per second per second for acceleration. F refers to the number of times a vibrating object vibrates per second. If we talk about the amplitude distance between the peaks of vibration or the distance a vibrating. The gravitational constant g is still widely used for acceleration levels al though it is outside the iso system of coherent units.

Acceleration can be expressed in the true values of m sec2 rms or gravitational units g where 1g is equal to 9 81 m sec2 approximately. 1 vibration frequency unit. Psi kg cm2 x 14 223. Convert between commonly used vibration units such as.

Vibration can be expressed in metric units m s2 or units of gravitational constant g where 1 g 9 81 m s2. Pascal kg cm2 x 9 8 x 104. Which units should be used is really a matter of personal choice or more often geographic location. Vibration measuring instruments vibration terminology important parameters relating to vibration pickups vibrometers are described below.

Vibration velocity and acceleration are measured as zero to peak or rms.