To select the right isolator for the job, important consideration is required to

• load or total weight and number of mounting points
• recommended operating height
• degree of isolation
• operating pressure

The tables on pages 6 – 7 (catalog) contain the technical data needed initially. Detailed information can be found in the corresponding product datasheets. The following descriptions and explanations are based upon a simplified spring-mass system and the following basic assumptions:

• The isolators are free of damping.
• The mass of the machine is small in comparison with that of the floor.
• The machine is a compact rigid body.
• The exciting force behaves harmonically.

• Load capability
  When selecting the isolator, there should be sufficient load-bearing capability to compensate asymmetric load distribution or excess weight. ContiTech air isolators have been designed to absorb dynamic increases in load from operating vibrations.
• Recommended operating height
  Air isolators generate their load capability by means of variable internal pressure. Consequently, static compression comparable to that of steel or elastomer springs is not associated with air isolators. There is no direct relationship between the load exerted and the height of the air isolator. Changes in the compression caused by varying loads can be compensated by adjusting the operating pressure. To ensure optimum isolation and lateral stiffness, isolators should be used at the recommended operating height. If any deviations from this operating height are necessary, check with ContiTech's Air Spring division or your distributor.
• Degree of isolation
  The degree of isolation is a measure of the isolation of vibration excitation. Vibration isolation exists only if the exciting frequency is at least 1.4 times greater than the respective natural frequency.
• fe >√2· fo
  The degree of isolation can be read from fig. 7.1 with the parameters natural frequency and exciting frequency. For example, a degree of isolation of 98% means that only 2% of the exciting force is transmitted by the air isolators; 98% of the excitations are isolated.
• Operating pressure
  The required operating pressure in relation to the load and operating height is specified on the datasheet. As a rule, the size of the air isolator is correct if the operating pressure is between 4 and 6 bar. Check that the compressed air pressure available on site is sufficient, taking into account fluctuations in pressure and pressure loss in fittings. If not otherwise specified, all pressure values given are positive.