A pump is a device that moves a gas or liquid from one area to another. This can be done by accelerating the liquid using centrifugal forces (centrifugal/rotodynamic pumps) or by grabbing a certain amount of liquid and physically pushing it towards where it needs to go (positive displacement pumps). Pumps are perhaps the most widely used mechanical devices and their designs vary as much as their applications.
Centrifugal Pump Monitoring Options
Special Case - Large Vertical Pumps
Large pump applications, such as the one shown above, require a more thorough monitoring scheme than smaller applications.
Metrix provides a vibration sensor for all bearings and a Datawatch monitor. The Datawatch monitors all vibration and temperature readings and compares them to pre-programmed setpoints in order to change the state of alarm and danger relay outputs.
Special Case - Pumps with Journal Bearings
Journal bearings use a layer of oil to isolate the shaft from the bearing. Therefore, the shaft is actually floating on a cushion of oil and has no contact with any other metal. Because of the oil layer, a vibration signal produced by the shaft does not have a path to travel to the machine casing. That means that a seismic sensor placed on the case of the pump cannot properly sense what is going on with the shaft.
This makes it necessary to use proximity sensors to detect shaft faults. A proximity probe mounts through the case of the machine and senses the position of the shaft relative to the probe tip. The pump casing holds the probe steady so that any movement in the shaft will cause the proximity probe / transmitter to give an indication. This type of measurement is termed “relative” because the shaft movement is being measured in relation to the machine casing.