ONLINE MONITORING OF WATER IN GEAR OIL APPLICATIONS

The EASZ-1 online water emulsion monitoring - Monitors dry oil and emulsified oils PDF DATASHEET>>

Application Notes:

Most Gearbox systems generally consist of white metal or rolling element bearings, steel on steel gears or steel on bronze gears of various configurations. The assembly is invariably fitted within an enclosure that provides both protection from external contamination and geometric alignment for the gear mesh.

Speeds and loads vary considerably depending upon the application and position of the gear within the drive train.

Simple, usually smaller, gear train systems rely on oil bath and splash lubrication. Larger and more sophisticated systems may have pumped oil supply with coolers as well as associated oil cleaning equipment such as filters and coalescers. Dedicated centrifugal oil treatment systems are desirable but rarely applied because of the high cost.

The more critical, usually much larger gear boxes systems where there is a risk of contamination from external sources particularly water from a cooler and oil deterioration. Such systems tend to have relatively large oil capacities. Oil management will usually be by periodic oil sampling and monitoring of oil conditions. Oil changes may not routinely take place and oil will only be changed when necessary to rectify problems.

For those systems where it is appropriate to manage the oil by periodic oil sampling, testing should aim to assess the extent of any oil contamination and also the degree of oil degradation that has occurred. Oils within the gearbox systems require to be regarded as a wearing component. Online Monitoring using the EASZ-1 online water Monitor and periodic maintenance provide assurance that the machinery will continue to operate predictably with the least risk of problems occurring.

The two most important contaminants for gear oils are water (fresh or salt) and engine lubricants that can upset demulsification properties of the oil. The combination of both will of course present the risk of stable emulsions of oil and water being formed. This can cause a variety of problems, the more important of which may be:

• Spoilt oil film conditions at bearing and at gear teeth contacts.
• Erosion/corrosion of gear/bearing surfaces.
• Spoiling of oil through microbiological contamination.

Online monitoring of water content in gear oils can be an added advantage . When interpreting analysis data on water content in gear oil systems, the key points to bear in mind will be that water will adversely affect oil film conditions. Effects on oil film conditions are likely to be more significant as loading at gear contact surfaces increases.

Where the contamination is sea water, additional problems are potentially created. Sea water is likely to be very much more aggressive than freshwater with respect to corrosion at all bright metal surfaces (gear/bearings). Corrosive activity associated with sea water contamination is likely to be pervasive and continue to take place when machinery is shut down. It is possible that corrosion rates could increase when oil drains down from exposed internal bare metal surfaces.

EESIFLO's loop powered lightweight water in oil transmitter can measure water in dissolved state, emulsions and free water. The fact is, it measures total water. It does not rely on the need to stay well below the saturation level of the oil to keep working. Gear box applications have been known to work well with smaller amounts of water. However, the amounts will usually be well over the saturation level of the oil.

The EASZ-1 is a very accurate capacitance measuring device. However, to turn this capacitance information into accurate reporting of water content in oil, the unit must correlate measured capacitance (at temperature) to actual water content in the process oil.

Each EASZ-1 electronics unit is factory calibrated to reference capacitances. This calibration data is stored in the unit, and due to the low, or almost non-existing, drift in modern components, there is no need to recalibrate the electronics. Older types of capacitive instruments had onboard trimmable capacitors requiring recalibration every now and then. The EASZ-1 has no such requirements.

The only important aspect of calibration are dielectric properties of the process media , the temperature coefficient, and finally a tuning of the zero to the actual process.

Here are some features:

• Dielectric Calibration/Linearization
  EASZ-1 uses a lookup table to correlate a measured capacitance to water content.
• Temperature Compensation
  EASZ-1 uses a Temperature Compensation (TC) factor to correct for oil temperature dependency. Capacitance of oil changes slightly over temperature.
• Zero Offset
  A factory supplied calibration, or one made on site may very well give you a correct reading as soon as you mount your instrument. It is however quite possible that the oil in your system slightly differs from any sample taken to a lab, or sent to the factory for calibration. If standard values of common new oils are put into the EASZ-1 tables, and the EASZ-1 is then set up to measure used oil, most likely a zero offset error will be introduced.

This does in no way mean that your calibration is off; it simply means you have to provide some more information and the EASZ-1 will automatically offset the tables accordingly.

The EASZ-1 has a built in default calibration table. Normally the default table will give good readings at low water content with almost all oils, however, it is likely that accuracy is compromised as water content goes up. In many applications this may be acceptable and putting in any extra work for calibration may not be required.

However, if it is necessary to change the zero offset of the default curve/table to the actual media or sample oil , this can be performed on a bone dry oil. If the application has large temperature variances, then the Simple Calibration can be improved by determining a factor for temperature compensation

Full Calibration can also be performed (most likely for higher water content oils) by filling in the calibration tables with data from known water content samples and by following the "Capacitance to Water Content Procedure".

For more information, please contact your local EESIFLO representative or log onto www.eesiflo.com

Eesiflo has a growing collection of data for different oils and may be able to supply you the correct values. For oils not yet in our collection, the factory may perform this service. Contact your EESIFLO regional service centre for details

SAE CONNECTIONS NOT A PROBLEM!

Another connection which is commonly used for higher flow and higher pressures is the SAE 4-bolt split flange type, a picture is shown below, Here, two flanges are clamped together by a split clamp, the hydraulic seal being made by a face located O-ring. A variation of this design is also available as a solid flange

Water contamination in oil has traditionally been monitored through spot sampling. Although the spot samples can be handled with care and taken to the laboratory for analysis, the problem remains that a spot sample is only indicative of the condition of the oil at the time the spot sample was taken. With the EASZ-1 online water monitor, operators do not need to stop their spot sampling or laboratory tests but have the added comfort of a 24 hour real time status report of the oil.