United States Army
Chemical Dosimeter


This is a two phase chemical dosimeter.
The olive-drab metal case dimensions are: 2¼” wide x 3¼” tall x ¾” thick.
The cover is embossed with: “US Army - Dosimeter - Radiation Tactical - EIR3”
The inside of the front cover reads “Keep closed except when reading, Lot NY-4620-23  2-55.”
Also known as a Colormetric Dosimeter, this type is for gamma measurement and detection only.

The bottom half of the unit contains five glass vials, which contain chloroform and a stabilizing chemical
called resorcinol and bromecresol purple dye, that are partially visible through a viewing window.
The two vials on the left are larger in diameter while the three on the right.

The instructions printed above the viewing window read:
“Shake then read in vertical position. Purple dye turns yellow-orange after exposure to”
And below the viewing window is the following:
 “50, 125, 175, 300, 450 Roentgens. Avoid prolonged viewing in direct sunlight.”

Front and Back Views
Note belt clip on back, this unit is all steel construction.

  Here's how they work:
The chloroform forms an acid when irradiated, and the amount of acid formed is directly
proportional to the amount of radiation absorbed. To measure the acid content, a pH sensitive dye is
added that changes color according to the acidity of the solution. The indicating dye is added to
the chloroform/resorcinol in various concentrations, depending on the range of radiation to be measured.

See Also:
Radiophotoluminescence Dosimeters
Direct Reading Ionization Dosimeters

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