Tool Time

Some people who have seen my tool collection think that I have WAY too many tools in my RV, and that is probably true.

Some of my more unique tools are my titanium crow bar, torque adapter, total dissolved solids (TDS) meter, endoscope and refractometer.

This article is about the last tool on this list. A refractometer measures the index of refraction of a liquid.  More info on refractometers is at Wikipedia HERE.

Our new RV is the second vehicle I have owned that is powered by Diesel fuel, and the first that has an EPA mandated after treatment system.  This is a spinoff of the exhaust treatment systems that are used in combustion power plants to keep our air clean.

The exhaust system on our bus has a Selective Catalytic Reduction (SCR) system (Wikipedia article HERE) that converts any nitrogen oxides, also referred to as NO_x and particulate matter (soot) that my engine produces with the aid of a catalyst into diatomic nitrogen (N₂), and water (H₂O). To aid in this process, my engine injects Diesel Exhaust Fluid (DEF) into the SCR.  When I was told that I would have to purchase DEF, I put it in the same category as blinker fluid, diesel engine spark plugs, first generation Volkswagen radiator caps, and from my Navy days, sound powered phone batteries, HT punch, a spool of shore line and those famous sea bats. Unlike everything else on this list, DEF actually exists!

DEF is a urea and water solution made with 32.5 (± 0.7) % urea and 67.5% (making up the remainder) deionized water. I would like to trust, but I need to verify that the DEF I purchase in the store will not damage my very expensive after treatment system. To measure the percentage of urea in DEF, a refractometer can be used in the field.

My first ten gallons of DEF and refractometer

I purchased an inexpensive, and therefore cheap, refractometer from Amazon.com for under $25 delivered. It is not laboratory calibrated, so my measurements must be taken with a grain of salt.

I am able to do a field calibration using pure water. I have a demineralizer, and my inexpensive TDS meter said I had zero parts per million of dissolved salts in the water.  Here is the refractometer reading pure water.

Note the blue area ends right at the water line.

So when I do the math, DEF must be 25-33.2% urea and here is what the refractometer indicated what the percentage was in all four jugs.

 

The top right scale is for DEF.

I felt confident that the DEF I was pouring into my DEF tank was good enough, even though it was the lowest priced DEF I could find.

I will test all DEF I put in my RV as I would rather error on the side of caution, instead of paying thousands of dollars on repairs.

  Where Are We Going Next?