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.

   Click on images for larger pictures

S Chamber

An electret is paired with a precision, volumetric E-PERM ion chamber to comprise a working E-PERM radon detector.
E-PERM ion chambers are manufactured from electrically conductive polypropylene. Inlets are filtered to allow only radon by passive diffusion and to block radon daughters. E-PERM radon detectors are also designed to have an insignificant response to thoron. The standard size (S) chamber is the most popular size. It has these special features:

• Spring-loaded cap for turning the detector 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 detector.
  

Click on images for larger pictures

L-OO Chamber

The L-OO little ion chamber has an on-off slider mechanism to turn the detector on or off. Its function and features are similar to the S chamber but with a smaller volume. This extends the exposure time by a factor of approximately six.

Click on images for larger pictures

Electrets

The electret is a Teflon disk which has been electrically charged and stabilized. Electrets are supplied in either Short-Term or Long-Term versions.

For indoor testing, where 200 Bq/m³ is the level of interest, the following guidelines are recommended:

Short-Term electrets with the S chamber will measure radon in approximately 48 hours. A four to seven-day test is ideal.

Long-Term electrets with the S chamber will measure radon in approximately 28 days. A 90-day test is ideal. Appropriate chamber and electret combinations are needed for high concentration measurements.

Short-Term electrets with the L-OO chamber will measure radon in approximately 12 days. A one to three-month test is ideal.

Long-Term electrets with the L-OO chamber will mesure radon in approximately six months. A one-year test is ideal.

Where high radon levels are expected, shorter exposure times can be used. For example, if the radon level is expected to be over 400 Bq/m³ an L-OO chamber with a Long-Term electret is a good choice for a three-month test.

  Click on images for larger pictures

Gently-used electrets

These have on average 5% less than the usual starting voltage of 700V.

Discount 20% off the quantity price while supplies last. Quantities up to 50.

Tamper-Resistant Testing Box

Holds two S chambers, two L chambers or two L-OO chamber detectors.  

  Click on images for larger pictures

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).

The Radon Flux Monitor consists of a set of two flux chambers that you use together to produce the radon flux measurement.

  Click on images for larger pictures