Article about fuel quality alert

There are various different kinds of minerals, microorganisms and other substances in fuel, natural and manmade.  Sometimes, even minute changes to the composition can mean the difference between a safer and more powerful fuel type to regular fuel.  Hohner has a high tech sensor, E504, which measures these properties in a non-contact manner using several simple optical principles.

Back in 2002, the prototype version of this sensor won second place in the Emhart/NASA contest.  Since then, the sensor has been put through field tests and modifications to make it market-ready.  Once the sensor had all the functionality required, it went for UL intrinsic safety certification.

Flashing lights and photo detectors are placed around a boro-silicate glass cylinder and together with optical filters and masks give readings pertaining to the physical quality of the fuel.

Example readings:

• Refractive Index – calculated using Snell’s Law, pure H₂O has a value of 1.33 and in comparison, oil has up to 1.60.
• Polarization – calculated using the cosine-squared-rule, with a filter in front of the light to give it a known value and using the polarization of the liquid as the second medium.
• Fluorescence – based on the principle that certain substances glow while a certain wavelength of light is shown upon them.
• Luminescence – based on the principle that certain substances glow for a while after a light has been shown upon them and turned off.
• Rayleigh scattering – occurs when emitting photons are elastically scattered by the absorbing photon.  (emitted in the same wavelength as the absorbing photon)
• Raman effect – occurs when emitting photons are inelastically scattered by the absorbing photon.  (emitted in a different wavelength as the absorbing photon)

All applications for this sensor are considered to be in hazardous locations (Europe Zone 2, 1 or even 0 and US Class 1) and the danger of an explosion is always imminent during normal use.  Therefore, Hohner has taken the necessary steps to make the device intrinsically safe to Class 1 Group A, B, C and D according to UL standards.  This certification is even if fuel leaks onto the electronics themselves, even though that would not happen.

The sensor is calibrated to 100% pure alcohol and anything the sensor measures is as a deviation from this.  So using the above optical principles, the sensor shows the deviation for each type of measurement.  It does not give an absolute reading for Gasoline, Diesel etc…  It shows how different it is from 100% pure alcohol.  Since the data changes with temperature, the sensor also measures temperature.

Hohner Corp. in Canada has a fuel sensor installed in Beamsville for field testing.  The sensor is in compliance with hazardous area regulations.  This means that a safety isolator series AB, also made by Hohner, has to be used.  Therefore, at the moment we have the sensor hooked up to the isolator which in turn is hooked up to a GSM telephone modem with a SIM card.  The telephone modem is readily available from Nokia, Motorola and others and any provider will assign a number to it.  Power supply for the isolator, sensor and modem is pulled from the modem battery or line power.

There are two ways to get a reading from the sensor.

1. Using your cell phone, send the text message “read” to the sensor, and after a few seconds you will get an answer from the sensor as a text message with the following data:

REFRACTION                      XXX.X = max + / - 99.9 %

POLARIZATION                 XXX.X = max + / - 99.9 %

FLUORESCENCE                 XXX.X = max  + / - 99.9 %

TEMPERATURE XXX.X = max 100.0 degree C

2. Using your PC, send an SMS via MSN, Yahoo or AOL to the sensor and receive the same data as above on your PC screen.

Applications for refraction

Fuel and lubricant

Most common for fuel quality testing is the use of the refraction index. Alcohol, all types of gasoline, diesel etc have all a known refractive index. Water content can easily be measured by taking in calculation the measured refractive index and both, the known refractive indexes from the fuel and water. It gets more complex when more than 2 substances like gasoline alcohol and sometimes diesel fuels are mixed together.