Vaisala MMP8 Moisture in Oil Probe

MMP8 incorporates the latest-generation Vaisala HUMICAP® 180L2 sensor, which is the result of over 15 years of field experience. It was developed for demanding moisture measurement in transformer and lubrication oils and other liquids.

The sensor's excellent chemical tolerance provides accurate and reliable measurement over a wide measurement range, with outstanding sensitivity in the dry end of the range – typically needed in transformer applications.

MMP8 measures moisture in oil in terms of water activity (aw), relative saturation (%RS), and temperature (T). Water activity or relative saturation directly indicate whether there is a risk of free-water formation. This data is relevant in lubrication oil applications where detecting water ingress and preventing free water formation is crucial. The measurement is independent of oil type and age.

In addition to water activity, MMP8 can output ppm, the average mass concentration of water in oil. Vaisala has this conversion readily available for mineral transformer oil. For other oils, the oil-specific conversion coefficients can be calculated if the water solubility of the oil is known and the solubility characteristic remains constant. This allows the continuous measurement of ppm concentration in power transformer condition monitoring.

MMP8 can be installed with the ball-valve installation kit even in processes where the probe needs to be installed or removed while the process is running. The probe installation depth is adjustable and pressure fitting options are ISO 1/2" and NPT 1/2". MMP8 is delivered with a manual pressing handle that allows the probe to be pushed against process pressure.