Water Detection in Oil and Fuel

EASZ-2 online water in oil/fuel analyser

What are the sources of Water contamination in an oil?

Over 70% of the world is covered in water, so its no surprise that water can make its way into an oil. Detecting water in oil is important when the amount of water content exceeds design limitations of equipment using oil, especially when continuous lubrication is a must. Too much water in fuel can also cause a malfunction.

Some examples of how water creeps into systems is through condensation in tanks, leaking heat exchangers, leaking coolers or even the presence of water from a process. It is not always possible to ensure that a design has a “water tight” system and that ingress or contamination never occurs.

What kind of damage can be caused by water in oil?

Water in oil can cause components to function less optimally than what they were designed for. The most obvious evidence is normally the presence of corrosion (rusting) as well as fatigue on rotating parts like bearings. Component wear, jamming and even the formation of ice crystals needs to be avoided in systems where their effects can cause unwanted damage, capital loss and in some cases even the safety of personnel

Sampling of Water in Oil vs Continuous Measurement?

At any moment of the day, there are people taking samples of oil to test for water content either using a centrifuge method or some laboratory device e.g. Karl Fisher laboratory testing. Sampling frequency needs to be increased when water contamination needs to be “caught” in a timely manner so that action can be taken. In many cases, this excessive sampling is not only costly but also time consuming and where measurements are necessary at all times it is not so effective.  The EASZ-2 online water in oil/fuel analyser is an instrument that has been designed by EESIFLO International to give operators a chance to not only immediately detect the presence of water in an oil system but also to accurately measure the amounts present at any time

Why use the EASZ-2 for water in oil measurements?


The EASZ-2 is a modern day “Easy 2 Use” online instrument that is far more accurate and repeatable than it’s predecessors. It has been designed to faithfully maintain accuracy/repeatability in industrial environments without compromising precision, especially in lower concentrations of water.


The EASZ-2 display will give not only a visual indication of the water content but also a backlight status e.g. green for normal condition, yellow/amber for approaching limits and red for alarm conditions. The electronics give the user a choice of a milliamp output, a contact output or Modbus communication as standard. The unit is also CE compliant and has been designed and tested to meet the most recent European EMC requirements.


The EASZ-2 Ex is also available for oil and gas industry applications. The electronics are housed in an Exd enclosure with a choice of intrinsically safe outputs.
The EASZ-2 was released in late 2017 and is currently now in full production. If you would like more information to see if EESIFLO can meet your needs, please contact us by email (

What is a water in fuel sensor?

A water in fuel sensor is a device that detects the presence of water in a fuel system. Often used for some control function when the moisture content reaches a determined set point.

What is the difference between moisture and free water measurements?

Moisture in a fuel is often detected at low levels and sensors have been designed to determine an increase in moisture levels over time.  Moisture meters normally respond very slowly and are limited in their range (only measuring moisture) but free water measurements enable operators to identify when other problems have occurred such as water break out.

The EASZ-2 can measure both gradual moisture increases over time as well as the presence of free water in real time.  Operators will have the added advantage of knowing when an event has occurred e.g. a sudden increase in water droplets in the fuel pipe during operation. Such measurements are taken once per second.

water in fuel sensor

EASZ-2 Water in Fuel Sensor

The EASZ-2

The EASZ-2 moisture in fuel detector is a modern development  which performs highly repeatable and highly accurate online measurements of the water content in fuel with the option to transmit readings through traditional analog signals or Modbus.

In many instances, fuel is not normally supposed to contain any amount of moisture and quality checks/ manual sampling are not sufficient to determine contamination levels at all times.  The EASZ-2 was designed to continually provide the user with the actual state of the fuel in real time.  Armed with immediate real-time sensor data on the moisture contamination in a flow fuel stream, it is possible to correct process anomalies before they become too problematic.


The EASZ-2 is currently being manufactured and supplied to standard “off the shelf” applications but is not limited by its standard design. The product can be configured to meet additional requirements through the addition of add on boards and custom firmware. Consult EESIFLO to find out more on how we can be of assistance


  • Zone 1 – Explosive Atmosphere Certification
  • Ability to measure low ranges of moisture in fuel
  • Measurement of total water in fuel or hydrocarbons in ppm or percent
  • Optional Loop powered outputs
  • Direct Temperature reading of Fuel with compensation
  • Immediate response to change in state of the fuel
  • Low, Medium and High Ranges


  • Diesel Contamination data collection
  • Any Fuel Type
  • Moisture in Hydrocarbons
  • Gas Condensate quality
  • Water in Fuel Emulsions
  • Fuel Separator Control
  • Thruster Sea Water Detection

Water Cut Meters


The EASZ-1 oil/water monitor is a highly accurate online analyzer that is installed in a pipe and can be used as a BS&W (Basic Sediment & Water) monitor or a water cut meter.

Watercut meter measure the H2O content (percentage) of crude oils and similar liquids in a flowing stream. The American Petroleum Institute refers to this as OWD or On-Line Water Determination.

Ideal for applications for first ,second and third stage crude oil separators , crude oil transfer in pipelines and in tank truck terminals. The watercut is expressed as a percentage of water in the total fluid stream.

A BS&W monitor is primarily used in a LACT system where “off spec” crude oil is diverted. One of the reasons could be the presence of excess amounts of water in the crude oil

Water and Oil do not normally mix and gravitational separation causes oil to travel along the top of the pipe and the water to travel along the bottom creating a phenomenon called "bottom water".  If this two part solution is not thoroughly mixed before it enters a watercut meter, it is very likely that watercut measurements will be inaccurate. In some cases it is possible that the water will be missed entirely.

EESIFLO International manufactures water-cut analyzers with built in integral mixing elements upstream of our EASZ-1 Water in Oil sensor, thereby creating a homogeneous mixture as it enters the sensing element. We also manufacture separate inline static mixers (EESIMIX) but the integral spool piece design is often preferred since a single spool piece will homogenize and analyze the fluid in one product.  Optional sampling ports can be added downstream of the mixing elements as required.


EESIFLO® can assist in the selection of a range of water-cut meters that are manufactured “off the shelf” products to cover most general applications which might suit the purpose without any additional economical impact. Our manufacturing facility holds stock for a line of most commonly used water cut meters.

EESIFLO ® is also an engineering and design company. Some of the common questions involving the selection of the correct meter will be :

  1. Line size, Line material, Schedule (Dimensional Constraints Yes/No)
  2. Pressure Rating, Flange Type
  3. Flow rate max/min
  4. Type of fluid
  5. Ambient Temperature, Fluid Temperature
  6. Water content range e.g. 0-1%, 0-25%, 30-60%, 80-100% , 0-100%
  7. Accuracy Requirements
  8. Documentation requirements / Welding, Radiography / Pressure Equipment Directives
  9. Area Electrical Certification requirements USA/Canada/Europe/Asia/Australia/Korea/India and others.
  10. Local and remote indication requirements/ Signal Output Requirements
  11.  If NACE MR0175 required
  12.  Mixer Requirements – Integral static mixer (EESIMIX)
  13. Sample Port Requirement (downstream of the mixer)
  14. Other considerations pertaining to the location and application requirements, special materials, additional tests/documentation.
  15. Painting specifications
  16. PED Requirements (Module H)
  17. Factory Acceptance Tests
  18. Others