The Bently Nevada 990 Vibration Transmitter and 991 Thrust Transmitter are two cost-effective monitoring solutions designed for use on smaller, non-critical machinery, typically centrifugal air compressors with fluid-film thrust bearings.

990 Vibration Transmitter:

• Provides a 4-20 mA signal proportional to relative vibration.
  
• Employs an integrated proximity probe, eliminating the need for a separate external unit.
  
• Features a Not OK/Signal Defeat circuit to prevent high outputs due to malfunction or loose connections.
  
• Ideal for original equipment manufacturers (OEMs) seeking a simple solution for integrating vibration monitoring into their machinery control systems.

991 Thrust Transmitter:

• Provides a 4-20 mA signal proportional to thrust position.
  
• Designed for measuring up to 1.2 mm or 50 mils of total thrust movement.
  Utilizes a Bently Nevada 3300 NSv proximity probe and matching extension cable (sold separately).
  
• Similar to the 990, it incorporates a Not OK/Signal Defeat circuit and is well-suited for OEM applications on centrifugal air compressors and small pumps, motors, or fans.