Gas tightness

Care must be taken to ensure that all connections are gas-tight. 

Apparatus 1-1 three-necked, round-bottomed flask with a dropping funnel, a gas--tight mechanical stirrer and a very efficient condenser. The top of the condenser was connected to a cold trap (-80°C). 

Apparatus 500-ral three-necked, round-bottomed flask, provided with a dropping funnel, a gas-tight mechanical stirrer and an efficient reflux condenser a trap and a tube filled with anhydrous calcium chloride were placed between the condenser and the water pump in such a way that during the reaction the vapour of the product entered the large annular space of the trap (see Exp. 24) the drying tube was placed between the trap and the water pump. 

Apparatus See Fig. 7 size of the flask, 2 1 a gas-tight stirrer should be used the top of the condenser was connected uia a plastic tube to 2 tubes filled with lumps of CaCl2- These tubes in turn were connected to 2 cold traps (-80°C) each of which contained 40 ml THF or CH3OCH2CH2OCH3 (free from peroxides). 

Apparatus 1-1 three-necked flask, provided with an evacuatable dropping funnel, a gas-tight mechanical stirrer and a 45-cm Vigreuxcolumn. The column was connected to a condenser and a single receiver, cooled at -75°C. Between the receiver and the water pump was placed a tube filled with KOH pellets. 

Apparatus. 2-1 three-necked, round-bottomed flask, provided with a gas inlet tube, a gas-tight mechanical stirrer and a gas outlet two washing bottles filled with paraffin oil were connected with the gas inlet and outlet. 

Apparatus 3-1 three-necked flask, fitted with a dropping funnel, gas-tight stirrer, efficient reflux condenser and a thermometer, dipping into the liquid. 

Air-Atmosphere Furnaces. These furnaces are appHed to processes where the workload can tolerate the oxidation that occurs at elevated temperatures in air. In some special appHcations, the oxidation is not only tolerable but is desired. Some furnaces heat the work solely to promote oxidation. Furnaces designed for air operation are not completely gas-tight which results in somewhat lower constmction costs. There are no particular problems encountered in selecting the insulation systems because almost all refractory insulations are made up of oxides. Heating element materials are readily available for the common temperature ranges used with air atmospheres. 

The helium leak detector is a common laboratory device for locating minute leaks in vacuum systems and other gas-tight devices. It is attached to the vacuum system under test a helium stream is played on the suspected leak and any leakage gas is passed into a mass spectrometer focused for the helium-4 peak. The lack of nearby mass peaks simplifies the spectrometer design the low atmospheric background of helium yields high sensitivity helium s inertness ensures safety and its high diffusivity and low adsorption make for fast response. 

Dynamic explosion detectors use a piezoresistive pressure sensor installed behind the large-area, gas-tight, welded membrane. To ensure optimum pressure transference from the membrane to the active sensor element, the space between the membrane and the sensor is filled with a special, highly elastic oil. The construc tion is such that the dynamic explosion detec tor can withstand overpressures of 10 bar without any damage or effect on its setup characteristic. The operational range is adjustable between 0 and 5 bar abs. Dynamic explo-... 

A stirrer which gives efficient stirring near the walls of the flask is advisable. The fittings should not be gas tight since oxides of nitrogen and bromine are evolved during the reaction. It is advisable to work in a hood or out-of-doors. 

Wear proteetive elothing sueh as rubber or plastie aprons, rubber gloves, gas-tight goggles and respiratory equipment as appropriate. 

Berth operator to take reasonably practicable steps to control flammable or toxic gas escapes (e.g. hose support, flange couplings liquid- or gas-tight, drip trays). 

A heated sample line through which the sample is directed onto the filter tape in a gas-tight holder... 

Fan, gas-tight A fan with a casing that will provide a set air leakage rate at a given operating pressure. 

Gas-fabrik, /. gas works, -fach, n. gas engineering. -fang, m. (Metal.) gas take, gas catcher, gasfest, a. gasproof, gas-tight. 

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