Mekorot Ltd. (Israel’s national water company) operates more than 600 water wells with depths that exceed 50 meters. In northern Israel alone, there are approximately 200 such wells. At these wells, which are all oil lubricated, we have installed a system that supplies oil in pre-defined quantities to ensure the proper operation of the line shaft.

The supply of oil to the line shaft’s bearings can be compared to the supply of blood to the brain. Should the flow of oil stop for any reason, irreversible damage is caused that shortens the equipment life. Later on, it requires the dismantling and replacement of the well equipment.

The following are reasons why the oil drip can stop without notice :

a) The oil tank is empty b) Dirt in the oil c) Changes in oil viscosity due to weather changes.

In the early 1990’s, a change over to using paraffin food grade oil began that replaced the use of machine oil. The quality of lubrication provided by the new oil was of a lower level than the original oils used. Due to this change, operational problems began with these wells for what appeared to be for no apparent reason. Due to these problems, it was decided that instrumentation needed to be developed for the regulation and drip monitoring for our oil lubricated wells.

Hoffmann and Hoffmann Ltd., which had developed other application specific electronic instrumentation for Mekorot in the past, was asked to find a solution to the above referenced problem, in cooperation with our in-house engineers. After extensive R&D efforts, a technological solution was developed. Tests were conducted on a small number of wells initially, in order to identify possible modifications needed to ensure maximum effectiveness. Due to the success of the trial period, the system was installed on all oil lubricated Mekorot wells throughout the country (more than 350 wells).

The system enables the establishment of a constant drip rate during well operation (the number of drips per minute is a function of the depth of the well) and a lower drip rate when the well is not operating. Most of the units we have installed have been in use for over five years and have demonstrated a high level of efficiency requiring minimal maintenance.

Due to the fact that operating a well without oil causes irreparable damage and very high costs, the investment made to install and operate this system has been very worthwhile for our company.

It should be stressed that the units are operating year round in a variety of weather conditions including under snow in the winter, as well as in extreme heat (113 degrees Fahrenheit – 45 degrees Celsius) in the summer. The system withstands the significant changes in oil lubrication viscosity and maintains a constant and consistent drip rate according to our specifications.

I would like to mention the significant contribution these units have made to help avoid breakdowns in the equipment we operate, as well as the cooperation we have enjoyed from the people at Hoffmann & Hoffmann Ltd

These units have provided us with a technological solution for vertical line-shaft lubrication and even automatically shuts down a well if the lubrication stops for any reason, preventing the need for expensive repairs as oil viscosity can change dramatically due to changing weather conditions-very cold weather can seriously increase viscosity, stopping the flow of oil, the Dripmaster will shut down such a well, preventing serious damage to the pump. This small investment has been more than worthwhile as we extend the life of the bearings, save manpower costs and maintain peace of mind that the pumps are being lubricated according to the manufacturer’s specifications.

Vertical turbine pumps – Oil lubrication control system

Alon Lev , Mekorot Water Co, [email protected]

Mekorot, the national water company of Israel, is operating more than 1200 wells, about 400 of them are considered deep wells in which the turbine is installed at a depth of over 100 meters and oil lubrication is required.

In shallower wells, the pumped water can be used to lubricate the shaft bearings due to two reasons. First, the shaft bearings are made of rubber, and secondly only a short period of time elapses between the energizing of the motor and rising of the water up the pressure tube. Therefore the span of time that the well operates without lubrication is short.

In wells in which the water level is lower and the time required to reach the ground level is longer, the pumped water cannot be used as a lubricant. In order to prevent heating of the rubber bearings, they are replaced by bronze bearings (tube bearings), which require constant lubrication to avoid  seizing, wear, and tear.

Mekorot Water Co., the national water company of Israel, has developed with a local electronics lab (Hoffmann & Hoffmann), an oil lubrication control system. This system consists of enclosed oil tubes that are connected by steel bushings with inlaid tube bearings that contain the line-shaft within. The bearing itself is made of bronze to maximize the surface qualities and precision, with grooves to ensure uniform lubrication of the shaft. The enclosed tubes are held in place within the pressure tube by stabilizing spiders made of rubber.

The purpose of the oil-lubrication control system for deep wells is to prevent failures created by lubrication malfunctions. Dripping oil through the bearings and enclosed tube along the shaft lubricates the well. Lack of lubrication or an insufficient supply of lubricant causes accelerated wearing of the bearings that could lead to seizing of the shaft. The control system allows continuous oiling with remote monitoring and tuning, giving ultimate protection against lack of lubrication and regulates the lubricant quantity according to the predetermined amount. This lubrication control system has been installed in all of Mekorot’s oil lubricated wells.

According the maintenance procedures of Mekorot, the oil dripping rate during well operation is set at 20-40 drops per minute (depending on well depth) and the oil dripping rate when the well is not in operation is set to 10 drops per minute. The role of the lubrication control system is to regulate the drops in order to create a constant dripping rate in accordance with the predetermined values.

Should the dripping rate fall below 15 drops per minute when the motor is running, the control shuts down the motor automatically.
The dripping rate is regulated through an automated control system based on a servo- motor regulating valve that changes its position according to the actual dripping rate that is measured every minute. In order to check the device or in emergency situation, there is also a manual regulating option for the valve.

The oil container has an oil-level viewer, and is installed on a mount near the well. The oil tube is connected from the container through a filter and the oil controller.  The container should be situated at least 30 cm above the oil cup in order to maintain a constant downward slope of the oil tubing.

The oil controller regulates the oil drops that drip through the tube into the enclosed tube and bearings.

The system was developed with cooperation with Hoffmann & Hoffman, a local private company, after pilot installations proved to be successful. Mekorot equipped all its 400 deep wells with this system, all of them have been working successfully for about 15 years, with zero failures, minimal maintenance, and significant oil saving.

We estimate that the amount of failures due to improper line shaft lubrication were reduced by at least 50% after adopting the Hoffmann & Hoffmann Dripmaster device and by that the ROI was proven.