There are 5 moisture density gauge manufacturers (Instro Tek recently purchased CPN) in the United States. All use Cesium 137 to measure density and all use Americium 241 to measure moisture. Although the quantity of radioactive materials in each of the gauges range from 8 – 10 mCi of Cesium 137 and 40 – 50 mCi of Americium 241, they all give an accurate representation of density and moisture.
When purchasing a new gauge always ask for a discount and be willing to get a quotation from several different manufacturers. Most manufacturers will match competitive quotes but will want to see a copy of the competitive quote. In addition to the discount some companies will offer further incentives such as a free calibration, free leak tests or discounts on future parts and service.
There are many older generation gauges still in use and service and repair centers do an excellent job in refurbishing these gauges. Some gauges still in use are approaching 25 years old. If you have a gauge that is 10-15 years old you will want to consider the options of purchasing a new gauge or refurbishing the gauge you have.
Most gauge manufacturers sell refurbished gauges and give a one year warranty on the gauges. Many independent gauge service and repair centers also sell refurbished gauges. Shop around and compare prices. A refurbished gauge should include a new calibration, current leak test and warranty. You can also buy a used gauge from a geotechnical or paving company that is selling their extra gauges. The price of the gauge is usually lower but you will want to factor in the cost of any potential refurbishing and calibration.
As mentioned, new gauges all use the same radioactive materials and approach to determine density and moisture and should all give the same results. Base model gauges generally require you to manually record (handwrite) your results and standard counts, and manually enter the depth setting. This approach is fine for most gauge users and will save you the cost of unnecessary software.
More advanced and costlier gauges offer all kinds of bells and whistles. You will need to determine if you really need or will use these enhancements. Some will offer loads of data storage that you may not need. Some offer auto storage for your gauge results and standard counts. Other will automatically compute or translate your results. There is a trade-off on enhancements – the greater the number of enhancements the more complicated the gauge. Do you want your gauge operators taking tests or fooling around with software? Make sure it’s worth the effort. And all those extra enhancements can mean more frequent and expensive service and repair bills.
If you are trading in or disposing of an old gauge many manufacturers will offer an extra discount towards a new gauge, but only if they determine the gauge you are trading in can be refurbished and re-sold. If it’s too old they will not offer the discount and will likely add on a disposal fee. Request that they give you a normal discount and try to include the disposal for free.
CPN (Now owned by Instro Tek)
5052 Commercial Circle
Concord, Ca 94520
Model MC1 – no longer in production. Measures moisture & density.
Model MC1-DR Direct Readout – no longer in production. Measures moisture & density.
Model MC1-DR-P Portaprobe – Measures moisture & density.
Model MC3 – Measures moisture & density. Thin layer mode.
551-D Pylon Drive
Raleigh, NC 27606
Model 5001B – Measures moisture & density.
Model 5001P – No longer in production. Measures moisture & density.
Model 5001C – Measures moisture & density.
Model 5001EZ – Measures moisture & density.
3008 Cornwallis Rd
Research Triangle Park, NC 27709