1 General and Specifications
1.1 Introduction
This Density/Moisture Gauge, the HS-5001EZ, is specifically designed
to measure the moisture content and density of construction materials.
The microprocessor-based units automatically computes these parameters
and makes corrections to the measurements.
It uses the attenuation of gamma radiation due to Compton scattering and
photoelectric absorption. It is directly related to the electron density of ma-
terials as an indication of the mass density of specific materials having
a chemical composition approximating the crust of the earth.
The standard factory supplied density calibration is based on a material
consisting of 50% limestone and 50% granite as being very close to the
average material encountered in engineering construction. This calibration
may be altered by the user to best fit other materials, which may have a
chemical composition vastly different from the supplied calibration.
The measurement of moisture content is based on the thermalization
(slowing down) of fast neutron radiation. It is predominately a function of
the hydrogen content of the materials and to a lessor degree, by other
low atomic number elements such as carbon and oxygen. The presence
of chemical elements such as boron, which may absorb or capture thermal
neutrons, will also have some effect on the accuracy. Hydrated minerals
such as gypsum or crystals such as mica may cause the largest single error.
In general, a material containing hydrogen, which is not removed during an
oven dry procedure, as outlined in ASTM D2216 will cause an error in the
measurement.
The standard factory supplied moisture calibration is based on a water
saturated silica sand standard, which is used to calibrate a working standard.
The user, to correct for other materials, may alter the calibration.
THIS INSTRUMENT CONTAINS RADIOACTIVE MATERIALS,
WHICH MAY BE HAZARDOUS IF IMPROPERLY USED.
HUMBOLDT recommends that users participate in a radiation safety and
applications training program given by competent instructors. Where this is
not possible or impractical, users should study the Radiation Safety Manual
supplied with this instrument and carefully read this Instruction Manual to
become familiar with the safe operation of the instrument.
A Radioactive or By product Material License is required from an Agree-
ment State or The US Nuclear Regulatory Commission for possession in the
United States. The governments of other countries require a similar license.
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