1. Bradley’s Study

3. Hammertek Bends

4. HammerTek Valve

5. 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.

6. Knudsen’s Analysis

7. Solt – Fuller Study

8. Idaho Nuclear Results - Bodnar

9. 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.

10. 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.