Inlet velocity recommended

The unit shown in Figure 4-49 has been used in many process applications with a variety of modifications [18,19,20]. It is effective in liquid entrainment separation, but is not recommended for solid particles due to the arrangement of the bottom and outlet. The flat bottom plate serves as a protection to the developing liquid surface below. This prevents re-entrainment. In place of the plate a vortex breaker type using vertical cross plates of 4-inch to 12-inch depth also is used, (Also see Reference [58].) The inlet gas connection is placed above the outlet dip pipe by maintaining dimension of only a few inches at point 4. In this type unit some liquid will creep up the walls as the inlet velocity increases. 

Equation (15) gives the variance per unit length of a GC column in terms of the outlet pressure (atmospheric) the outlet velocity and physical and physicochemical properties of the column, packing, and phases and is independent of the inlet pressure. However, equation (13) is the recommended form for HETP measurements as the inlet pressure of a column is usually known, and is the less complex form of the HETP expression. 

The ozonised air must be evenly distributed throughout the chamber and the fan in the ASTM cabinet achieves this, but at the expense of an uncontrolled air velocity. Probably, a better procedure is to use a diffuser at the gas inlet and also to attach the test pieces to a mobile test piece carrier such that each test piece visits every part of the cabinet at intervals. Such a carrier is recommended in the ISO standard. 

These are generally in the form of a U-tube attached by flexible connectors to the inlet and outlet lines of the instrument (Fig. 6.34). The instrument has a substantial volume (ID = 0.025 m) and, where flows are small (recommended minimum velocity = 1 m/s), it is probable that the whole process fluid stream, rather than simply a sample, will be sent through the instrument. 

Other factors to be considered include inlet and outlet designs. Installing inlet baffles with sized opening will enhance flow distribution across entire width and depth of the basin. Underflow baffles following the floatable removal system can also increase the removal efficiency of floatable particles. However, baffles must be deep enough to prevent pulling of the floatable particles under the baffle. It is recommended that flow velocity under the baffle should be limited to 1 ft/min (21). 

---