Bradley’s Study

Hammertek Bends

HammerTek Valve

Knudsen’s Method and Solt Approximation Knudsen -Calculation related directly to the square of the velocity of the gas. Solt – uses 20 pipe diameters as an equivalent length for a bend.

Knudsen’s Analysis

Solt – Fuller Study

Idaho Nuclear Results - Bodnar

1. When replacing long radius bends with short radius bends or “'Tee” bends, systems with low velocity conveying and/or high material to air ratios will result in increased capacity or reduced conveying pressure. 2. When replacing long radius bends with short radius bends or “'Tee” bends, systems with high velocity and/or low material to air ratios will result in decreased capacity or increased conveying pressure.

1. The service life of blinded tee configurations is at least 15 times that for radius bends with R/D’s ranging from 8 to 24. The service life of blinded lateral configurations is at least 7 times that of radius bends. The velocity of particles impacting the piping walls of the blinded configurations is significantly lower than that for radius or mitered bends, thereby increasing the erosion resistance of the blinded configurations. 2. Pressure drop and calcine attrition rates are not significantly different for blinded tees as compared to radius bends. 3. Long radius bends do not have significantly increased service life relative to short radius bends. 4. The erosion rate of the radius bends is Proportional to particle velocity raised to the 4.2 power. 5. The service life for 30 degree radius bends is similar to that of 90 degree radius bends. 6. Poor alignment of piping sections results in a potential localized erosion failure point. Blinded lateral designs are more easily aligned during fabrication than are blinded bend designs. 7. Many particles have sufficient momentum to exit failure points countercurrent to the in-leaking air in a vacuum system. 8. Visual tests using glass pipe provided an effective means of analyzing particle flow in the various bends and straight pipe sections.