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$179.99 GRL-100, 0-100% Glycerin in Water; Antifreeze Glycerine w/ Lighted Daylight Plate


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Item Description: NI Supply GRL-100 Portable 0-100% v/v Glycerin Refractometer - WITH LED light built in!



New Firespinkler laws got you worried?  Worry no more! 

You've found the unit to test the concentrations of Glycerin in Water and determine your pipes FREEZE POINT!

This is the Refractometer the Professionals use!

The Users Guide that comes with the unit will show you the Freeze Point of Glycerin and Water Solutions in 'F and 'C!  Consult your products MSDS/Technical Datasheet for product specific protocols for measuring their brand of Glycerin based Antifreeze.


GRL-100 Specs:

* Scale Range: 0%-100.0% Percent Glycerin in Water

* Resolution: 0.5%
* Accuracy: +/- 1.00%
* Dimensions: 28mm x 28mm x 155mm
* Weight: 138 grams/5.5 ounces

Included are: A plastic hard case, calibration screwdriver, pipette and Users Guide. and a LIGHTED DAYLIGHT PLATE

One BRAND NEW NI Supply GRL-100 (0% to 100.0% v/v Percent Glycerin Scale) Hand held Digital Refractometer in a Gray, foam-lined plastic hard case. This unit is especially handy for testing of water pipes of potable water.  Calibrate with Distilled Water (water = 0%) and wipe clean with a cotton towel, and you're ready to go!  You have highly accurate results in seconds!  This is a very powerful and simple to use unit that has a GREAT PRICE! The daylight plate allows a clearer picture to the scale allowing more light making it much easier to read 
Pre-mixed solutions are generally purchased at a 48% concentration, so this unit will read correspondingly - 48%!

For Glycol Antifreeze, please consider our other units designed specifically for Glycol (Ethylene and Propylene) Glycols.


Glycerine as an Antifreeze

  • Glycerine, also known as glycerin or glycerol, is a naturally occurring sugar alcohol. Glycerine lowers the freezing point of water by inhibiting ice crystal growth. Its low toxicity makes it a common choice for weatherproofing residential and commercial fire sprinkler systems. The National Fire Protection Association (NFPA) sets standards for sprinkler systems and requires that any system expected to be exposed to freezing temperatures must be protected by an antifreeze solution. NFPA code 13 requires any sprinkler system connected to a public water source must use a glycerine antifreeze solution rather than ethylene glycol to reduce the risk of poisonous chemicals returning to the water supply. In fire suppression systems containing chlorinated polyvinyl chloride (CPVC) pipes glycerine must be used as an antifreeze as ethylene glycol can corrode the plastic pipes and fittings.

Concentration and Testing

  • Fire suppression systems use a closed loop to isolate freeze-proofed areas. A check valve keeps antifreeze from returning to the main sprinkler system. Glycerine offers highest antifreeze protection at a 70 percent concentration by weight. At this level, pipes are protected against freezing to minus 36 degrees Fahrenheit. Above this concentration glycerine will begin to freeze at higher temperatures: pure glycerine begins to solidify near 32 degrees F. Check with your local Fire Marshal to find the concentration required for your climate. Manufactures offer premixed glycerine solutions though you can blend your own mixture using food-grade glycerine and distilled water. Open the filling inlet to load the antifreeze into the sprinkler system. Use a laboratory grade hydrometer or a refractometer to test that the glycerine solution is identically concentrated at the filling inlet and at the drain valve at the furthest point in the sprinkler line. Retest the concentration level during the annual inspection of your sprinkler system.



National Industrial Supply 
30777 Rancho California #891420
Temecula, CA 92589, USA
Sales: 951.308.9269  -  Fax: 310.733.5480  -  E-mail:  -  Website:

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