AUTOMATIC CONTROL

Dominion, Volume 29, Issue 200, 21 May 1936, Page 13

AUTOMATIC CONTROL

New Zealand Lagging Behind in Use APPLYING THE SYSTEM “Automatic control has been—or could be —successfully applied to many New Zealand industries. Although in other parts of the world it is accepted as a very necessary part of a plant, there is still a lot of leeway to be made up in New Zealand before we can claim to be really up to date in most of our industries,” said Mr. J. S. Ellis, when addressing members of the technological section of the Wellington Philosophical Society on the subject of automatic control last night. “The timber industry has been a consistent user of automatic control during the last four years. The only application in New Zealand is. of course, in the drying of timbers, since as yet there is no pulping done. Among its many uses in the meat industry, probably the most outstanding is the application of automatic control to the Iwel Laabs dry-rendering system. This is a process used for the production of tallow and stock-feeding meals, in which the offals from slaughtered animals are rendered, cooked and dried while agitated in a specially-constructed steamjacketed vessel. The process comprises five stages. Another important place for control is in the scalding of pigs. "The dairy industry has been rather the bad boy so far, and there is no' more obvious need for control than in the pasteurisation of milk. Properly-con-trolled pasteurisers would not make even a small percentage of the whole. The cry is that money cannot be found to spend, say, £7O on an automatic controller recorder —but stop to think of the hundreds, or, rather, thousands of pounds' worth of milk handled by even one pasteuriser, and the sales effect of varying grades of butter, etc,, that result from poor handling. “The cold storage of fruit and eggs calls for very close control of the atmosphere in which the goods are stored. Humidity ami temperature are critical and in any reasonably large store it is an easy matter to provide adequate means of control. It does not make any difference whether the store is brine cooled or ammonia cooled.

"Woollen mills are at present a virgin field. Rather strangely, too. for there bag lieeu such wonderful siiecess of control work overseas. The reiuatks about woollen mills apply equally to bakeries. So far as I know, only one South I.sland bakery has made any move in the right direction. One large bakery actually has its loaf cooler alongside its cooking oven. “Colour printing, chocolate enrobing and cigarette manufacture also fall into the class which require controlled atmospheres.” continued Mr. Ellis. "In foundries, the most interesting application is in Ute control of the weight of oxygen admitted to the blast furnace. The necessity for this is the need for castings free from flaws and blow holes, the necessity for iron not burnt, etc. "The automatic control of chromium plating plants is exceptionally interesting. as in chromium plating the temperature of the plating bath has to be kept constant and during the first part of the process this involves the supply of sufficient heat and in the latter part of the process cooling Ims to be applied to the bath. This cooling is necessary since the process of plating actually builds up the temperature of tbc bath, and after a period of time the bath would become too hot if left to itself. A special type of duplex control is used for this.”