E-PERM System Starter Kit

SPER-1E Electret Reader

The electret voltage reader is a highly sophisticated electric-field sensor with a special receptacle into which the electret is placed. When the shutter is opened, the sensor can read the voltage on the electret surface without touching it. Readings of the electret voltage, before and after deployment provide an absolute number for unambiguous, quantitative determination of the ion collection accomplished by the electret due to radon in the chamber.

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S Chamber

An electret is paired with a precision, volumetric E-PERM chamber to comprise a working E-PERM Radon Monitor. E-PERM radon chambers are manufactured from electrically conductive polypropylene. Inlets are filtered to allow only radon by passive diffusion. E-PERM radon monitors are also designed to have an insignificant response to thoron. The S chamber is the most popular because of these special features:

• Spring-loaded cap for turning the device on or off
• Hole through the open stem to allow a 1/8 inch lock tie security seal
• Hanging ring on the cap to suspend the device

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Electrets

The electret is a Teflon disk which has been electrically charged and stabilized.

Short-term electrets with the S chamber will measure radon at a level of 200 Bq/m3 in approximately 48 hours. A 4 to 7-day test is ideal.

Long-term electrets with the S chamber will measure radon at a level of 200 Bq/m3 in approximately 28 days. A 90-day test is ideal. Appropriate chamber and electret combinations are recommended for high concentration measurements.

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Tamper-Resistant Testing Box

Holds two S Chamber monitors.  

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Radon Flux Monitor

The passive measurement of radon flux from the ground or other surfaces used for determining the radon emanating potential of a building site or to meet regulatory measurement requirements for uranium mill tailings or gypsum stacks.

The flux monitor features a large, diffusion window. The chamber is vented so that it will not accumulate the radon concentration. When the E-PERM Flux Monitor is placed on a radon emanating surface, the radon enters through the diffusion window and exits through the vents. The semi-equilibrium radon concentration inside the camber is representative of dynamic flux from the surface. The discharge rate of the electret is a measure of the radon flux. E-PERM Flux Monitors have been calibrated on the well-characterized radon flux beds at CANMET (Canada), which are known to produce radon flux of 7.7 + 1.1 pCi m^-2 second ^-1 (Flux Units).

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