Perforating metal

Metal Pan Assemblies. These units consist of tiles and panels formed from perforated aluminum or steel with pads of fiber glass or mineral wool inserted into the pans to provide the sound absorption. They are used primarily for ceilings in a similar manner to acoustical tiles and panels. The pads are sometimes sealed in plastic film to prevent absorption of moisture, dirt, and odors. The perforated metal is relatively sound transparent and functions as the finished ceiling and the support for the sound-absorbing material. The perforated metal by itself has no acoustical value. 

The fixed-tubesheet exchanger is the most common, and generally has the lowest capital cost per ft of heat-transfer surface area. Fixed-tubesheet exchangers consist of a series of straight tubes sealed between flat, perforated metal tubesheets. 

Grill not intended to change the direction of air, consisting oi parallel lamina ribs, perforated metal grid, wired grid, etc. 

The technology of kerosene burners is quite mature. The most popular kerosene heater is the perforated sleeve vaporizing burner or range burner (Figure 1). It consists of a pressed steel base with concentric, interconnected grooves and perforated metal sleeves, between which combustion takes place. Kerosene is maintained at a depth of about 1/4 inch in the grooves. As the base heats up, oil vaporizes from the surface, and the flame lights from asbestos wicks. Combustion air is induced by natural draft. The flame is blue, and the burner is essentially silent, odorless, and smokeless. 

Plate-type catalysts (PTCs) consist of metal sheets, metal net, or perforated metal plates with the catalytic species deposited onto, assembled in modules that are inserted into the reactor in layers [58, 59]. Several innovative structures have been reported. Figure 9.9 gives an example of a structure permitting some vibration of the individual plates, reducing possible blockage the plates are very thin, reducing the pressure drop. 

The build up of pressure is aided by the use of a breaker plate, which is a thick disk of perforated metal positioned just downstream of the tip of the screw. A screen pack, comprising layers of woven metal mesh, is placed on the upstream side of the breaker plate. The screen pack increases back pressure within the metering zone and acts as a filter to catch any extraneous material that may have entered the extruder. 

A fluidized-bed reactor consists of three main sections (Figure 23.1) (1) the fluidizing gas entry or distributor section at the bottom, essentially a perforated metal plate that allows entry of the gas through a number of holes (2) the fluidized-bed itself, which, unless the operation is adiabatic, includes heat transfer surface to control T (3) the freeboard section above the bed, essentially empty space to allow disengagement of entrained solid particles from the rising exit gas stream this section may be provided internally (at the top) or externally with cyclones to aid in the gas-solid separation. A reactor model, as discussed here, is concerned primarily with the bed itself, in order to determine, for example, the required holdup of solid particles for a specified rate of production. The solid may be a catalyst or a reactant, but we assume the former for the purpose of the development. 

More popular and widely used these days are relatively small and simple osmometers based on the Zimm-Meyerson design (Zimm 1946), in which two membranes are held against a glass solution cell by means of perforated metal plates, as shown in figure below. 

Very little will be said here concerning the equipment aspects of plasma etching. There are three basic types of equipment which have been used a) barrel systems, b) planar systems, and c) systems in which the wafers are located downstream from the plasma to be referred to in this paper as downstream etching systems. These plasma etching configurations are shown schematically in Fig. 3.1. Often the barrel systems are used with a perforated metal tube called an etch tunnel which is shown in Fig. 3.1 a and b. The purpose of the etch tunnel is to protect the wafers from the energetic ion and electron bombardment to which waters immersed directly... 

The relation between the high pressure inside the cartridge case and the lower pressure in the bore could be varied by increasing or decreasing the size or number of the openings in the separating disc. In order to protect the propellant in the container from spilling and from moisture, the perforated metallic disc was covered with a solid disc of paraffined cardboard... 

Many early experiments were carried out with the Meker type of burner. A perforated metal plate is placed on top of an open pipe (the thicker the plate, the more stable is the flame). On ignition, a number of small cones... 

Materials that require more than a few minutes drying time or are in small quantity are treated on a batch basis. If it is granular, the material is loaded on trays to a depth of 1-2 in. with spaces of approximately 3 in. between them. Perforated metal bottoms allow drying from both sides with improved heat transfer. Hot air is blown across or through the trays. Cross velocities of lOOOft/min are feasible if dusting is not a problem. Since the rate of... 

Figure 13.14. A centrifugal packed fractionator, trade name HIGEE, Imperial Chemical Industries. Units have been operated with 500 times gravitational acceleration, with 3-18 theoretical stages, up to 36 in. dia, employing perforated metal packing. For distillation, one unit is needed for rectification and one for stripping. Units have been used primarily for gas stripping and on offshore platforms because of compactness [Ramshaw, Chem. Eng., 13-14 (Feb. 1983)].

Sarkar et al135 used a modification of the 180° peel test with a perforated metal sheet at the interface to improve the reproducibility of the tack measurement and studied the effect of a number of parameters on the values obtained. 

When using peel tests on such products as belts to separate the plies, it can be difficult to obtain interfacial failure. Loha et al47 successfully used test pieces including a perforated metal sheet at the interface to measure rubber to rubber adhesion strength. 

To a large, glass, cylindrical beaker C is fitted a metal cover with a central aperture through which passes a test-tube b into the latter fits another test-tube a of somewhat smaller diameter but widened at the upper part. The tube a is closed with a perforated metal cover carrying a thermometer t reading to 0-5° and supported by three spring tongues conveniently fixed below the orifice in the cover. 

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