Impingement ovens

Baking is the other common alternative for expanding half-products. Air impingement ovens are recommended because of their high rate of heat transfer. The development of products for microwaving and production of low-fat itans is gaining popularity. 

Alternatively, air bubbled through an impinger containing 15 mL 0.2 N NaOH solution HCN converted into NaCN content of impinger transferred into a vial, rinsed with 2 mL 0.2 N NaOH (total volume 17 mL) sealed and heated overnight in an oven NaCN hydrolyzed into sodium formate contents cooled and diluted to 50 mL formate ion analyzed by ion chromatography (Dolzine etal., 1982). 

Carbon-14 content is measured by specially designed gas proportional counters (7. Aerosol samples are first converted to CO2 by combustion in a macroscale version of the thermal evolution technique. A clam shell oven was used to heat the sample for sequential evolution of organic and elemental carbon under equivalent conditions. Due to the possibility of thermal gradients, conditions in the macroscale apparatus were adjusted to produce the same recoveries of total carbon (yg C per cm of filter area) as for the microscale apparatus. Carbon-14 data are reported as % contemporary carbon based on the 1978 1 C02 content in the atmosphere. Aldehyde data referred to in this paper were obtained by impinger sampling in dinitrophenylhydrazine/acetonitrile solution and analysis of the derivatives by HPLC with UV detection (12). Olefin measurements were made by a specially designed ozone-chemiluminescence apparatus (13) difficulties in calibration accuracy and background drift with temperature limit its use to inferences of relative reactive hydrocarbon levels. 

The oven cavity holds the material to be heated so that microwaves ean impinge on them. 

Will the molecules travel in the beam at the same velocity First of aU, the molecules impinging on the oven orifice have a Maxwell-Boltzmann velocity distribution given by... 

FIGURE 47.11 Arrows indicate impinging forced-convection flows from oven blowers. The inadvertent thermocouple junction (crossed wires) will record oven local air temperature rather than the intended measurement target the solder-joint area. 

Our basic apparatus is shown in Fig. 1, except that the polarization accessories are not immediately required. A primary beam of calcium atoms is produced by resistively heating an oven (nozzle diameter about 0.7 mm) to approximately 1400 K. A DC discharge between a ring electrode in front of the nozzle and the nozzle exit serves to excite approx. 20% of the atoms into metastable states [9]. After coUimation, this beam enters the collision zone and impinges on a secondary gas. 

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