Innovation of Blackening Labu Sayong

The blackening technique of Labu Sayong (LS) or clay pitcher commonly performed either traditionally or in modern way is by removing the clay pitcher from the firing area one by one after the firing temperature reached maturity at around 850°C to 900°C. A finding indicates a few improvements can be done such as reducing the time of transferring the clay pitcher to the paddy husks, reducing the fuel consumption, uniforming the blackened effect of Labu Sayong and reducing the defects ratio of Labu Sayong. The innovative is to add paddy husks or organic materials into the kiln as soon as the firing temperature reached maturity during the cooling process. The paddy husks will get burnt and produce a thick smoke. By closing all the burner port holes and chimney damper, the smoke will diffuses inside the firing chamber which gave the blackened effect to Labu Sayong. Based on the studies, the best temperature to add the paddy husks into the kiln is between 350°C to 700°C, depending on the size of the kiln. The innovation blackening Labu Sayong can overcome the disadvantages of the conventional blackening technique while increasing productivity without additional operation costs.

Burner Design Criteria and Variables Affecting Flashback of Acetylene Flames

A study is presented on the operating characteristics of burners employing premixed, laminar flow air–acetylene and nitrous oxide–acetylene flames. The variables affecting flashback of these flames have been investigated and found to be critically dependent on such factors as burner port diameter, gas flow, fuel–oxidant ratio, and burner construction. Because the theory previously developed for stable flame formation on isothermal burners is not directly applicable to most burners used in flame spectrometry, an operational theory of flashback is developed. In accordance with this working model, safe limits of operation for conventional burners are examined and presented and important burner design criteria are established, including experimental quenching diameters for both circular port and slot-type burners.