Rotor Balance Requirements

Precision balancing requires a G2.5 guide number, which is based on 2.5mm/sec (O.lin/sec) vibration velocity. As can be seen from this, 6.3mm/sec (0.25 in/sec) balanced rotors will vibrate more than the 2.5mm/sec (O.lin/sec) precision balanced rotors. Many vibration guidelines now consider 2.5mm/sec (0.1 in/sec) good, creating the demand for precision balancing. Precision balancing tolerances can produce velocities of 0.01 in/sec (0.3mm/sec) and lower. 

Rotor balancing shall be performed as required in the specific pump sections. 

These experimental demonstrations confirm that silicon microfabrication is a valid approach to implement microturbines. The relatively simple structures survived the centrifugal loads at high speeds. In addition, rotor balancing was not required after fabrication, a required step for traditional high speed rotors. 

No special rotor balancing facilities required conventional commissioning. 

One is the so-called A-plane approach. This approach states that only A-planes are necessary for a rotor system running over Ncritical speeds. The other technique, called the (N + 2)-plane approach, requires two additional planes. These two additional planes are for the two-bearing system and are necessary in this school of balancing. 

Rotor speeds are such that dynamic balancing is required for proper vibration control. Also, while the critical speeds are generally above the operating speed, review of the rotor dynamics should not be ignored, jwi ticularly for the dry type. 

ISO 1940/1, Mechanical Vibration—Balance Quality Requirements of Rigid Rotors—Part 1 Determination of Permissible Residual I nbal-ance, First Edition, International Organization for Standardization, Geneva, Switzerland, 1986. 

For best results, balance the rotor on its own shaft rather than on a balancing shaft. This may require some rotors to be balanced in an overhung position, a procedure the balancing shop often wishes to avoid. However, it is better to use this technique rather than being forced to make... 

For example, a 20-inch wide rotor could have a large enough couple imbalance component in its dynamic imbalance to require two-plane balancing. (Note The couple component makes two-plane balancing important.) Yet, if the 20-inch width is on a rotor of large diameter to qualify as a disc-shaped rotor, even some of the balance manufacturers erroneously would call for a single-plane balance. 

When rotors of higher flexibility are used at speeds above 3800 RPM, achieving and maintaining this balance level will require special attention to design, manufacture, and maintenance. 

Rectangular or Square Parallel Keys and Their Corresponding Keyways Cylindrical and I/IO Conical Shaft Ends Geometrical Orientation and Directions of Movements Mechanical Vibration—Balance Quality Requirements of Rigid Rotors—Part I ... 

ISO 1940-1, Mechanical vibration — Balance quality requirements of rigid rotors — Part 1 Determination of permissible residual unbalance. 

The usual precautions regarding temperature and vibration control also apply to the ultracentrifuge. To overcome air resistance and the attendant frictional heating, the compartment in which the rotor spins is evacuated and may be thermostated over a wide range of temperatures. The rotor is mounted on a flexible drive shaft that minimizes the need for precise balancing as a requirement for vibration-free operation. Finally, the rotor assembly is enclosed in an armored steel chamber for safety. At these speeds, a runaway rotor is deadly ... 

Studies of the catalytic reactions in the adsorbed phase require conditions of controlled atmosphere, which become especially challenging if the adsorbate is only weakly adsorbed or catalyst-adsorbate samples are air/moisture sensitive and require preparation on a vacuum line, including loading into the MAS rotor. The NMR cells must thus be carefully sealed. On the other hand, to achieve a sufficiently high rotation speed the NMR ceils must be well balanced (83). 

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