Hot air ovens

Tensile properties of importance include the modulus, yields, (strength at 5% elongation), and ultimate break strength. Since in many uses the essential function of the film may be destroyed if it stretches under use, the yield and values are more critical than the ultimate strength. This is tme, for example, where film is used as the base for magnetic tape or microfilm information storage. In some cases, the tensile properties at temperatures other than standard are critical. Thus if films are to be coated and dried in hot air ovens, the yield at 150°C or higher may be critical. 

Firing. A hot-air oven having forced circulation in a countercurrent mode is used to dry the fermented tea leaves and inactivates the key enzymes required for fermentation. The firing process generally occurs over an 18—20-min period, which is optimum for normal process efficiencies. 

The simplest and most widely used method of increasing the film temperature is to pass the coating through a convected hot-air oven. This is relatively inefficient, but effective with articles varying widely in shape and size. If... 

Dry heat sterilization is usually carried out in a hot air oven which comprises an insulated polished stainless steel chamber, with a usual capacity of up to 250 litres, surrounded by an outer case containing electric heaters located in positions to prevent cool spots developing inside the chamber. A fan is fitted to the rear of the oven to provide circulating air, thus ensuring more rapid equilibration of temperature. Shelves within the chamber are perforated to allow good air flow. Thermocouples can be used to monitor the temperature of both the oven air and articles contained within. A fixed temperature sensor connected to a chart recorder provides a permanent record of the sterilization cycle. Appropriate door-locking controls should be incorporated to prevent interruption of a sterilization cycle once begun. 

In addition to normal compression set test conditions, usually 22 hours at 70 °C in a hot air oven, pharmaceutical elastomeric closures may be subjected to compression set conditions simulating steam sterilization cycles in an autoclave for 30 minutes at 121 °C. Also, sterilizing cycles employing ETO, radiation, or dry heat are used. Comparison data between formulations are used to develop compression set values that will identify potentially acceptable compounds under these conditions. 

Gamma ray emitter units are available which can be located between a UHF system and a hot air oven. It may be necessary to adapt the rubber compound for use with this system. 

The filled oven test pallets are loaded into a hot air oven and the munitions are heated to 210 F and then maintained at that temperature for 15 minutes. The munitions are then returned to the UP plant for leak inspection, palletization and storage or transfer to an ammunition loading plant. 

In fact, it is extremely important to eliminate as completely as possible the solvent imbedded into the thin layer of coated adsorbent. It is achieved conveniently first by air-drying the TLC plates for a duration of 30 minutes and then in a hot-air oven maintained at 110 °C for another 30 minutes and subsequently cooling them in a dessicator. This drying process helps a great extent in rendering the adsorbent layer active. In order to achieve very active layers, silica gel and alumina coated plates may be heated upto 150 °C for a duration of 4 hours and colling them in a dessicator. 

Hydrolysis. To 0.50 ml of a protease solution or a dentin slice in 0.50 ml water was added 0.50 ml 12 M HCl. Nitrogen was blown over the solutions and the tubes were closed and heated at 111°C for 24 hours in a hot air oven. Aliquots were dried in triplicate in vacuo over NaOH for collagen determination and HPLC analysis. 

DNPT)) were studied using a gas evolution apparatus. The decomposition temperature of ADC decreased with both DNPT and 4,4-oxybis(benzenesulphonyl hydrazide) (OBSH) blending and this affected the structure and properties of the resulting foams. Using a tube mould for an extrudate to vulcanise the NR/EPDM extradate in a hot air oven was found to control the expansion and foam dimensions. The NR compositions affected the foam structure and properties. 16 refs. 

Two types of dry-heat sterilization systems are utilized in the pharmaceutical industry today. They are the conventional hot air oven and the tunnel system. The major difference between the two systems, as far as validation is concerned, is the belt or line speed variable with the tunnel system. 

Dry in a hot air oven — if any white streaks are found on the sides of the vessels the rinsing procedure is inadequate. This may be a result of failure to rinse sufficiently or it may indicate that the deionised water supply is faulty. 

The 121 sample films were formulated into a replicate series. Those utilizing emulsion polymerized PVC were cast from plastisol onto glass plates and fused in a circulating hot air oven. Those incorporating suspension polymerized PVC were fluxed via a Banbury and two-roll compounding mill and finished on an inverted L 8-inch X 16-inch four-roll calender. Plastisol films were of nominal 8-mil thickness calendered film was 4 mils. 

Food contact materials must be hardened in a hot air oven (80-100 °C) for a couple of hours. After the oven treatment the material must be washed for 1-2 hours with hot water (80 °C) in order to remove volatile and water soluble components. 

Moisture and Volatile Matter—Air Oven Method (M V) (Ca 2c-25) determines the moisture and volatile matter by heating in a hot air oven. This method is applicable to animal and vegetable fats, but not to drying oils, coconut group fats, or oils with added monoacylgly cerols. 

Preheating is often used to reduce the molding cycle. It can aid in providing even heat through the material and can cause a more rapid rise in heat than occurs in the mold cavity. A warm surface plate, infrared lamps, hot-air oven, or screw/barrel preheater can accomplish preheating. The best and quickest method is high-frequency (dielectric) heating. 

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