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OTC

OTC 5025 Diesel Exhaust Fluid (DEF) Refractometer

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Availability: In Stock.
Fulfilled by Amazon
Arrives Wednesday, Apr 15
Order within 22 hours and 28 minutes
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Features

  • The refractometer is a portable precision optical instrument used for measuring the diesel exhaust fluid concentration
  • When a liquid sample is placed on the prism the light passing through it is bent and the more concentrated the liquid the more the light will bend
  • The refractometer contains a reticle or scale that is enlarged through the eyepiece to measure this light and the values on the scale have been established to evaluate the DEF condition
  • EPA regulations require all diesel engines manufactured on or after January 1 2010 to meet lowered NOx emissions standards
  • Most heavy duty engine manufacturers have chosen to utilize SCR including Detroit Diesel DD13 DD15 DD16 Cummins ISX line PACCAR and Volvo-Mack

Description

The Refractometer is a portable, precision, optical instrument used for measuring the Diesel Exhaust Fluid (DEF) concentration. When a liquid sample is placed on the prism, the light passing through it is bent. The more concentrated the liquid, the more the light will bend. The Refractometer contains a reticle, or scale, that is enlarged through the eyepiece to measure this light. The values on the scale have been established to evaluate the DEF condition. EPA regulations require all diesel engines manufactured on or after January 1, 2010 to meet lowered NOx emissions standards. Most heavy duty engine (Class 7-8 trucks) manufacturers, have chosen to utilize SCR. This Includes Detroit Diesel (DD13, DD15, and DD16 models), Cummins (ISX line), PACCAR, and Volvo/Mack. SCR-equipped engines require the periodic addition of Diesel Exhaust Fluid (DEF, a urea solution) to enable the process. DEF is available in a bottle from most truck stops, and some have installed bulk DEF dispensers near the Diesel Fuel pumps. However, to ensure the proper operation of the SCR system, operators must ensure the DEF in their vehicle consists of a 32.5 percentage Urea/Water solution. It makes this a simple and quick process for an operator or technician. Scale: 0.5 percentage, line graduations 32.5 percentage, indicated scale 15-40 percentage, waterline, and 20 degree Celsius kit includes Refractometer, dropper, lens wipe cloth, instructions and quick guide, screwdriver and case.

Brand: OTC


Material: Glass, Metal, Plastic


Item dimensions L x W x H: 12.3 x 5.9 x 2.85 inches


Item Weight: 1 Grams


UPC:


Brand Name: OTC


UPC: 731413559846


Global Trade Identification Number: 46


Manufacturer: OTC


Item Type Name: DEF Refractometer


Included Components: Unit^Instruction Guide


Unit Count: 1.0 Count


Warranty Description: 1 year manufacturer


Item Dimensions: 12.3 x 5.9 x 2.85 inches


Item Weight: 1 Grams


Material Type: Glass, Metal, Plastic


Frequently asked questions

If you place your order now, the estimated arrival date for this product is: Wednesday, Apr 15

Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.

To initiate a return, please visit our Returns Center.

View our full returns policy here.

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Similar Products

Top Amazon Reviews

    • Functionality.
So easy to use, the pamphlet instruction is included, it cost less than you order directly from OTC. The glass screen show your DEF testing fluids very clearly and 99% accuracy, works as it design for.
Reviewed in the United States on October 23, 2025 by D.T
    • What a great tool to have at a good price
Just bought a new 2023 semi truck $220k didn’t even have 3k miles when a check engine light with poor def truck derated shop said def was contaminated. I got a bill of $1900. I sent bill to seller he paid the bill contamination is not cover under warranty somebody had to pay that bill truck got fixed bought this tool every jug I put in I test well 3k miles again check engine light poor def again I told shop I checked every jug bought def fluid from there parts counter well shop gave me a bill for $6,200 i checked fluid and showed my refractometerwell they started doing there job come to find out the builder of the truck for some reason caked on a bunch of grease on O-ring that goes on sensor that was leaking into the tank and creating false readings and that’s where the contamination was coming from. I suggest if you have a semi truck that uses DEF buy this tool it’s worth every penny. By the way, the $6200 bill got covered under warranty. ... show more
Reviewed in the United States on February 25, 2023 by Ernie Robles
    • Works as advertized
Easy to use and read display. Accuracy unknown for lack of a known calibration fluid other than water, but new package of Blue DEF checked good.
Reviewed in the United States on July 9, 2021 by Stewart
    • Works great & accurate. Not "Optical Grade" as mine had a black spot above the water CAL line.
This DEF optical test device works perfectly and is quite accurate. My only complaint about OTC's claim of "optical grade quality" isn't quite true. My unit came with a quite noticeable black spot located a little above the distilled water calibration line. That's not optical grade in my experience!
Reviewed in the United States on November 21, 2019 by P. R.. Fectionist
    • Appears to be a quality tool
I’m pleased with the quality. It’s easy to read and use. Judging by the quality appearance, I’m going to believe it’s accurate. You are able to calibrate before each use. With DEF mfg now removing their “secret” date codes all together, you need something to verify the concentration of what you’re putting in the tank. ... show more
Reviewed in the United States on March 11, 2023 by JV
    • Only once have I bought bad DEF, which this detected
I use this every time I get DEF. Only once have I bought bad DEF, which this detected. Without the tester I might have put bad DEF in my truck. Prior to getting this refractometer, I had a specific gravity DEF tester. It was much less expensive but it was hard to tell what the reading was half the time; it was not consistent. The refractometer is much better and only takes a minute. ... show more
Reviewed in the United States on May 10, 2018 by Amazon Customer
    • Worth the money!!!! Great diagnostic tool.
I drive a 2014 Ram 3500 that uses DEF. Got an alarm the other day and upon determination the code said problem with DEF conductivity(weak DEF in tank). Service writer said I used cheap DEF (I didn't) and for a mere $1200.00 they would drain,flush,and re-fill tank with the "good" mopar DEF.Told him he was full of poop and to clear the fault code. Used my new OTC refractometer to check DEF in tank and it was fine. Now dealership will DO THEIR JOB and trace stray voltage/fault in DEF monitoring system. I got to wonder how many unsuspecting diesel truck owners whose engines require DEF fall for the $1200.00 drain and flush scam. Disgusting. ... show more
Reviewed in the United States on June 27, 2016 by Amazon Customer
    • I like the idea of checking the fluid
Works as advertised. I like the idea of checking the fluid; perhaps a bit OCD, but worth the peace of mind.
Reviewed in the United States on October 10, 2017 by Bill

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