The first step in installing an SSD system is called a communication, or Radius of Influence (ROI) test. This procedure allows the vapor removal specialist to quantify the airflow and pressure needed to depressurize the area directly beneath the buildings’ concrete floor. Some buildings require high airflow at low pressure and some require the opposite. Large buildings may have different characteristics in different places. The important thing to remember is no two buildings are alike.
The test starts with small holes drilled into the concrete at the edges of the building. A digital gauge is temporarily connected to these holes to measure differential pressure. Larger holes are drilled in areas where preferred suction points for the finished system are located. Different fan configurations are attached to the larger holes to quantify the amount of airflow and pressure needed to depressurize the target areas.
Using the results of the communication test, the number of individual suction points, pipe diameter, and fan configuration can be determined. This information is then translated into final system design drawings for owner approval.
By conducting a communication test as part of your SSD installation you can ensure that the system will be properly sized and will be effective at eliminating your VOC problem. Without this step both the vapor removal specialist and environmental engineer are at best guessing on what will work to treat the issue. Bottom line is, it’s worth the extra step to be sure that your project will be successful for you and your client.
This article was written by Tony McDonald
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