Why test? Very simply, thermal conductivity testing measures the ability of the ground, at a specific site, to transfer heat. This is especially important in commercial geothermal applications, where large amounts of heat must move in and out of the ground heat exchanger. The efficiency of the heat exchanger is important in determining its size.
Middleton Geothermal Services is affiliated with Ewbank & Associates of Fairview, OK, the developers of conductivity testing. Since 1996, Middleton Geothermal Services conductivity testing has played an integral part in the design of many successful geothermal projects in the Midwest. Over 130 thermal conductivity tests have been performed by Middleton Geothermal Services in the Midwest and the Northeastern United States.
Before commissioning a ground heat exchanger (the wellfield), it needs to be tested to make sure there are no small leaks and that joints have all been properly fused. Using Ewbank test units Middleton Geothermal can now test the field, or any portion of the field, using ASTM test procedure F 2164-02.
Because HDPE (High Density Polyethylene) materials are plastic, a pressure test is affected by pressure, ambient temperature, and the duration of the test. In other words, most pressure tests will fluctuate over several hours due to the pipe expanding or contracting. The Ewbank HDPE pressure test procedure provides a recorded comparison to pipe specifications as a way of proving the integrity of the ground heat exchanger.
Middleton Geothermal is making this state-of-the-art procedure a part of its in-house specifications for wellfield installation. This testing can also be provided as a service to an owner or construction manager as a part of a quality control or commissioning specification.