with 2.5-inch tapered pipe thread connections; (b) a 90 degree elbow with 2.5-inch tapered thread connections; (c) a nipple with 2.5-inch tapered thread connections; and (d) a flange with a 2.5-inch taper thread and ASME B16.5 bolted flange connections. Within the pipe components are two tubes. One tube is for vapor space equalization, and the other is a guide for positioning the level sensing equipment. Various material options exist for these components. The proposed system shown uses standard steel pipe. Alternative pipe materials, such as aluminum or composite, could be used for improved corrosion resistance.
Figure 3. Side View Rendering of Preferred Underground Composite Propane Tank
Vapor Space Connection
Use of a side port in the head of the tank creates a situation not found in standard installations. As the liquid level of the propane raises above the side port, the vapor space in the riser is separated from the vapor space in the tank. This would prevent the tank from filling beyond this point. To alleviate this problem, the two vapor spaces must be connected. This is accomplished by routing a tube through the port and into both vapor spaces. This tube is shown in Figure 4.
Alternative Underground Propane Tank Materials, Phase II—Final Report
September 2009 Battelle and Lincoln Composites