Conventional smoke houses replaced

Sri Lanka Rubber Research Institute introduces single day smoke drying unit for sheet rubber:

Ridma DISSANAYAKE

The Sri Lanka Rubber Research Institute introduced a single day smoke drying unit for sheet rubber to replace the conventional smoke houses which takes over five days to dry rubber sheets.

"Forty percent out of the total production of Sri Lankan rubber are produced as sheet rubber. In addition, around 25 percent are produced as crape lase, 25 percent produced as concentrated latex and other 10 percent is used to produce latex blocks. All kind of sheet rubber in Sri Lanka are produced by rubber industrialists in the country," an Institute spokesman said.

Since the inception of the local rubber industry, Ribbed Smokes Sheets (RSS) are hung in a smoke house for drying. It has been used in the Sri Lankan rubber industry for over 100 years. Certain chemical substances present in the smoke are absorbed on to the sheets during smoking. Conventional smoke houses used to handle larger crops consist of a building of two or three storeys, internal wooden racks to hang the sheets and an external furnace, the spokesman said.

The newly developed SS drying system, designed to overcome most problems in conventional smoke houses, consist of a well insulated enclosure, a trolley, a gravel layer, a perforated baffle plate system and an internal fire wood furnace or saw dust burner. Sheets are hung on the movable trolley in an open area and the trolley is then inserted in to the well insulated enclosure instead of hanging sheets on immovable wooden racks fixed inside conventional smoke houses.

Drying time of five days in a conventional drying system has been reduced to a single day in the novel system provided that sheets are manufactured according to the standard manufacturing procedure given by Rubber Research Institute to get a thickness of 2.5 -3 mm in sheets.

In this new system, trolleys are loaded and unloaded in an open area outside the enclosure. It is a much easier and efficient operation compared to the current practice. One of the major advantages of this new system is that operation is very cleaner and easy and hence labour attractive, the spokesman said.

In the new dryer, sheets are hung on trolleys which could be moved out of the drying cabinet. This practice is much easier and faster and therefore the labour output would be increased. Trolleys are moved out only once during the drying period to turn over the sheets. During this period, the dryer is kept closed and heat is retained on the gravel layer which acts as a heat storage unit.