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.