Slit vents

When a parison or preform is inflated, it displaces the air around it within the mold. If no provision is made to vent the mold, compression of the air around the parison or preform can raise its temperature to such an extent that it can scorch the surface of the product. To avoid this problem, we equip blow molds with vents. These can consist of slit vents at the parting line between mold halves, porous plugs of sintered metal, or small holes drilled into the cavity walls. 

Plutonium nitrate solutions are shipped, normally, at an authorized concentraUm of 250 g/liter in nitric acid at a maximum concentratioa of 6.0 ilf. A ha radiolysis of the solution results in pressure building within the polyethylene bottle which must be vented. Modification of the standard 83-mm closure was necessary to provide venting capability. Two typeh of vents were developed a slit vent arrangement, and a vent incorporattnig a patented valve known as the Duo-Vent. 

The engines are buried deep within the aircraft s interior reducing noise and heat signature. The heat signature is further reduced by mixing the jet s exhaust with cool air and exiting it through slit-like vents. 

When a PTV instead of a classic injector was utilized in the analysis of penicillin residues, the sensitivity and the precision of the analysis were markedly improved (45). With the cooled PTV injector, some microliters could be injected, and the split-splitless mode allowed solvent venting at low injector temperatures with open slit in a first step, and quantitative transfer of volatile or derivatized drugs by a freely selected linear heat-up rate between 2-12 C/s in the splitless mode in the second step. Sensitivity could be enhanced by multiple injections before heat-up. Nonvolatile components of a sample did not contaminate the chromatographic system, since they accumulated in the glass vaporization tube, which could be changed easily. 

In a 250-00. Erlenmeyer flask provided with a two-holed stopper which has a slit cut in one edge to serve as an air vent and which holds a thermometer, the bulb of which reaches almost to the bottom of the flask, is placed 31.5 g. (0.5 mole) of anhydrous nitric acid (Note 1). The flask is cooled below io° in ice-water, and 51 g. (0.5 mole) of acetic anhydride (Note 2) is slowly added from a buret through the second hole in the stopper in portions of about 0.5 cc. at a time. The temperature of the reaction mixture is never allowed to rise above io° (Note 3). After about 5 cc. of the acetic anhydride has been added the reaction becomes less violent, and larger portions, increasing gradually from 1 to 5 cc., may be introduced at a time with constant shaking. After all the acetic anhydride has been added, the stopper and the thermometer are removed. The neck of the flask is wiped clean with a towel, and the flask is then covered with an inverted beaker and allowed to come up to room temperature in the original ice bath (Note 4). 

This TSE consists of two parallel counterrotating screws, as shown in Fig. 6.53. The distance between the screw centers is L < Db, where Db is the barrel diameter thus, there is an open axial slit along the barrel. This type of extruder has advantages for the feeding of particulate solids (e.g., powder), venting, and devolatilization of the molten polymer. 

Cover the pie with the remaining round. Turn the edges of the bottom crust over the top edges and flute together. To allow steam to vent, make holes in the top crust. You can create a decorative pattern with a fork or a cookie cutter. I like heart cutouts, but simple slits with a knife will do the job too. 

Lip vents are narrow slits in the degreaser freeboard zone. They are almost always located at the top of the freeboard zone — adjacent to the top cover. And they almost always cover nearly the entire periphery of the degreaser. 

Inflation of the parison is normally accomplished with compressed air, but in some cases the vaporization of liquid nitrogen is used instead. If the air between the parison and the mold wall is not vented as the parison inflates, it will prevent the molten polymer from making uniform contact with the mold surface, resulting in poor surface finish. Slit-type vents may be provided at the mold parting line. 

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