Tunnel orifice

Figure 3.4 Common types of liquid distributors, (a) Ladder pipe distributor (6) perforated ring distributor (c) spray distributor id) orifice pan distributor (e) tunnel orifice distributor (f) notched-trough distributor (g) weir-riser distributor. (Parts a and c to f reprinted courtesy of Norton Company part b, reprinted courtesy of Koch Engineering Company, Inc. part g, reprinted courtesy ofGlitsch, Inc.)...

Ladder ( spider pipe ) Perforated ring Multiple epny Orifice pan Tunnel orifice Notched trou Weir riser... 

Figure 3.5 Examples of high-performance distrihutors. (a) Deck type (b) lateral arm type (c) tunnel-orifice type, with orifices drilled in the angled wall, just above the bottom of the troughs. Liquid leaving each orifice hits a baffle which spreads the liquid laterally. (Parts a and b reprinted courtesy of Norton Company part c reprinted courtesy ofGlitsch Inc.)...

Orifice distributors are also generally larger, more expensive, consume more vertical space, and are more difficult to support than most other distributors. Tunnel orifice distributors provide greater open areas for vapor flow, are easier to support, and are more suitable for large-diameter columns than orifice pan distributors. 

Orifice distributors are usually of the pan type (Fig. 3.4d) or of the tunnel type (Fig. 3.4e). The former t3rpe is best suited for small-diameter columns (<4 ft), while the latter is used in larger-diameter columns (>4 ft). High-performance variations of the Fig. 3.4e distributor are shown in Fig. 3.5a, c and 3.6a, d. 

Orifice tunnel distributors consist of parallel troughs with perforations for liquid flow in the trough floors. Vapor rises in the space between the troughs. The troughs are often interconnected by cross channels that equalize liquid levels in different troughs (Fig. 3.6d). Level-equalizing channels are most important in coliunns greater than 10 ft in diameter (111, 349). 

The dilution tunnel for the PAH collection has been described (9, 10). This system consists of a stainless steel dilution tunnel, a CVS device, and the unit for drawing off proportional streams from the total gas flow. The length of the tunnel is 6 m and its diameter is 0.45 m. At the point where the exhaust gas enters the tunnel there is an orifice creating turbulence for mixing the exhaust more thoroughly with the filtered air. The velocity of flow... 

Differential pressure flowmeters are suited to high- and moderate-velocity flow of gas and clean, low-viscosity liquids. Venturi flowmeters (Fig. 18.9(a)) are the most accurate, but they are large and expensive. Orifice flowmeters (Fig. 18.9(b)) aresmaUer, less expensive, and much less accurate than venturi flowmeters. Nozzle flowmeters (Fig. 18.9(c)) are a compromise between venturi and orifice flowmeters. Pipe-bend flowmeters (Fig. 18.9(d)), which can essentially be installed in any bend in an existing piping system, are used primarily for gross flow rate measurements. Pitot-static flowmeters (Fig. 18.9(e)) are used in flows which have a large cross-sectional area, such as in wind tunnels. Pitot-static flowmeters are also used in freestream applications such as airspeed indicators for aircraft. 

The Turbocraft water tunnel is a closed loop type system. Suction and discharge pressure taps are located the prescribed distances from the pump in accordance with the Hydraulic Institute code. The flow is measured using a sharp-edged orifice. The calibration of the orifice plate is based on NACA data. For cavitation testing a vacuum pump is used to obtain the desired tank pressurization value below atmospheric pressure,... 

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