Presses moving-head

Three principal types of batch presses are nsed vertical presses, moving head presses and pneumatic presses. These same presses are used for red winemaking (Section 12.6.4, Fignre 12.11). Press operating conditions have a greater inflnence on the quality of fresh grapes than fermented skins, which contain only approximately 15% of the total wine prodnced. 

Die plate n. (1) In injection molds, a member that is attached to the fixed or to the moving head of the press mold plate, (2) In extrusion, especially of pellets or shapes, the die plate is that part of the die assembly that is bolted to the outlet of the die body and contains the orifices that form the melt into continuous strands or a particular cross-sectional shape. 

Moving head presses have the significant advantage of being automatic and sometimes programmable. Chains and press rotation are used to break up the cake after decompression. This operation produces suspended solids and can lead to olfactory defects. 

During devatting, the grapes should be carefully pressed using a horizontal moving-head press or a pneumatic press. These presses do not affect tissue... 

Figure 13.4 gives an example of a pressing cycle with a horizontal moving-head press (Vaslin, 22 VT) in manual mode using whole, healthy and ripe Sauvignon. All pressings, as well as the first three cake break-ups, are executed at a slow basket... 

Fig. 13.4. Whole-cluster pressing cycle in manual mode with a moving-head press (VasUn 22 VT). p to /06 = pressure level FIi to Ils = pressure step C = crumbling, drying or cake break-up...

Correctly carried out to obtain quality juice, pressing with a horizontal moving-head press is necessarily slow. Additionally, due to mechanical constraints imposed by the basket, presses larger than 60 hi cannot be manufactured thus their use for quality white wines and small installations is to limited. 

As with horizontal moving-head presses, the pressing quality of pneumatic presses depends on the chosen pressing method and cycle. The general rules are the same. The maximum volume... 

In practice, the grape crop is collected in small containers and frozen in a walk-in freezer at varying temperatures as low as — 16°C. The grapes are then pressed in a horizontal moving-head press or in a pneumatic press. The fi eezing point of the richest grapes is sufficiently low that their juice may be extracted without difficulty. Table 14.5... 

The second way to unload a reciprocating compressor is with valve disablers. Most of the unloaders you have on your compressors are likely of this inferior type. They typically consist of steel fingers, which are pressed down through the valve-cap assembly. The fingers prevent the valve plate from moving. These valve disablers are far less costly than an adjustable clearance pocket. They may be used on both the crank and head ends of the cylinder. They can reduce the gas flow through a cylinder to zero. 

A piece of the crumb of the size of a pin s head is moistened on a microscope slide with a drop of water and covered with a cover-slip, which is carefully pressed and turned round and round with the tip of the finger. In this way those starch granules which have undergone but little alteration are separated and moved towards the outer part of the preparation, where they may be easily observed. Thus were obtained the preparations for the microphotographs 33 and 34 of Plate V (at end of chapter) both were obtained from pure wheaten bread, the former being from a loaf made from 80% flour (i.e., flour containing 80% of the grain) and the latter from a small fancy loaf. 

Finally, signs that do not reference time directly can also make use of the future is ahead metaphor (Taub, in press). For example, the dominant hand in the sign look-back-on ( reminisce ) moves from near the eyes, around the head, and behind the signer, look-forward-to is made with the same handshape but with movement upward and away from the signer. For both the signs continue and predict, the hands move forward, ahead the signer. 

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