Range Extender [Extender]

The Range Extender mixes fresh air with sample air to reduce the concentration of radon in the air fed to the RAD7 radon detector by an order of a magnitude, greatly increasing its effective range.

The extender consists of two parallel capillary tubes joined at one end to the outlet hose connector. Fresh air is fed to the input of one tube while the incident radon sample is fed to the other. A differential pressure sensor across the two tube inputs, with a needle valve for adjustment, is used to ensure that both capillary tubes have the same pressure drop across them.

With this system the radon concentration delivered to the RAD7 will be reduced by a factor of 10:1 regardless of the strength and flow velocity of the RAD7 pump. The pump can cycle on and off without affecting the reduction factor.

The Range Extender can be used for the measurement of very high radon concentrations in air, in soil gas and in water. It can also be used with any other instrument that has its own pump, for any gas. If used to extend the range of thoron measurement care must be taken to assess and correct for the additional decay of the thoron due to sample acquisition delay.