Tubular-plate batteries filling

Leady oxide manufacture is potentially very hazardous. It is therefore vital to take adequate measures to minimise, or even eliminate altogether, possible lead dust emissions out to the working environment and thus exposure of the personnel which would cause health problems. This is achieved by the use of a closed (isolated) leady oxide production equipment and transport pipes from the storage silos to the paste mixing unit. Special attention should be paid to file manufacture of tubular battery plates. Until recently, tubular plates were filled with a dry mixture of leady oxide and red lead powders. 

The tubular positive plate uses rigid, porous fiber glass tubes covered with a perforated plastic foil as the active material retainer (Fig. 2). Dry lead oxide, PbO, and red lead, Pb O, are typically shaken into the tubes which are threaded over the grid spines. The open end is then sealed by a polyethylene bar. Patents describe a procedure for making a type of tube for the tubular positive plate (90) and a method for filling tubular plates of lead—acid batteries (91). Tubular positive plates are pickled by soaking in a sulfate solution and are then cured. Some proceed directiy to formation and do not requite the curing procedure. 

Most often, high percentage (65 wt%) red lead and leady oxide blends are used for filling positive tubular plates for bofli traction and stationary batteries. 

In Europe, and less commonly in the United States, many of the heavy-duty battery positive plates are made in porous tubular sheaths. The grid is cast or injection-molded of lead, with long-flnned spines attached to a header bar and a connection lug. Individual woven fiberglass plastic sheaths or a multitube gauntlet are placed on the spines. These plates are filled wifh powder or with a slurried paste until the tubes are full. A plastic cap plugs the open sheath ends and becomes the bottom of the plate (Fig. 23.15). 

The production of tubular positive plates is in principle similar to that of pasted plates. A number of manufacturers use the same gray oxide as the basic filling substance. Sometimes the share or red lead or minium (Pb304) is increased above 25 or even to 100wt.%. The latter is more economic when the manufacturer runs his own minium plant then the expense of the chemical oxidation of lead oxide (PbO) to minium (Pb304) may be compensated by reduced formation cost. Furthermore, curing is not required, because of the high oxidation state, and the battery starts with full capacity when formed. 

Tubular positive plates are sometimes used in batteries for deep-discharge applications to reduce shedding of electro-active materials from the plate during cycling. The positive electrode has intercoimected porous tubes that are filled with positive lead paste. Lead rods in the centers of tubes are connected in parallel by a conductive lead bar at the top, and the bar is connected to the positive terminal. 

The constraction of a tubular or pocket plate nickel-iron cell is shown in Fig. 25.2. The active materials are filled in nickel-plate perforated steel tubes or pockets. The tubes are fastened into plates of desired dimensions and assembled into cells by interleaving the positive and negative plates. The container is fabricated from nickel-plated sheet steel. The cells may be assembled into batteries in molded nylon cases or mounted into wooden traps. The steel cases may be coated with plastic or mbber for insulation or spaced by insulating buttons. 

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