Contact manometer

The separating effect of the column is dependent in the first place on the load and this must therefore be kept constant during a test run. A satisfactory method is to control the rate of evaporation by the pressure drop, using a contact manometer (section 8.4.2), and observing the heat input on an ammeter. Before the load is... 

The apparatus must be adequately insulated and the column jacket provided with the requisite heat compensation (section 7.7.3). The use of an automatic column head (section 7.5.3) allows the distillation to be performed with a minimum of attention. In the present case it would be useful to place a contact thermometer, connected to a bell via a relay (section 8.2.2), in the column head. The thermometer would be set to the boiling point of benzene, and when a signal was heard, the initial reflux ratio of 9 would be increased, say, to 20. In the same way it would be progressively raised to the final value of 50. The load may conveniently be regulated by means of a contact manometer actuated by the pressure differential (section 8.4.2). In accordance with the amount of the charge the still pot may be a pilot-plant flask (section 7.6.1) or a round-bottomed flask of 4 to 10 litres capacity, heated by a flask heater (section 7.7.1). 

StiU pot heating by contact thermometers and contact manometers via electronic proportional controllers (c/. sections 8.2.2 and 8.4.2) ... 

An automatic control of the boil-up rate (load) by contact manometer (Figs. 387, 388). 

Transistor relays may also be used in coimection with contact manometers (< /. chap. 8.3.1 and 8.3.1.1). They are commercially available as a combination of standing or supported device. They operate on the normally open and normally closed principles where a circuit is switched on and off, respectively, on making a contact. These relays are further employed for photoelectric circuits, e.g. in the level control of liquids and in vacuum control (c/. chap, 8.6 and 8.3.1.1). As safety relays thev switch off the circuit if the contact thermometer fails. 

Compression manom ers of the McLeod type can also be employed in the 760— 1 min range. Since, however, their main field of application lies in the range of 10 to 10 mm pres.sure, they will be discussed under the latter heading. For the range of 0 to 60 mm water column electronic contact manometers are now-in use [36a]. 

Figure 9.16. A pressure controlled batch evaporating crystallizer A, 2 C crystallization vessel, B, baffle, C, stirrer, D, motor, E, variable speed controller, F, heating mantle, G, H, condensers, I, condensate receiver, J, drying tower, K, vacuum pump, L, contact manometer, M, electromagnetic valve, N, control box, P, electronic thermometer, R, vacuum gauge. After Mullin and Broul, 1978)...

In the case of a pressure drop in the system, a relay connected to the contact manometer 5 was turned on, and the circuit of an induction coil in one of the arms of the valve 6 was closed. An iron rod was drawn into the magnetic field of the coil, the mercury in the other arm of the manometer dropped, and oxygen from vessel 7 entered the system through a glass tube with a Schott filter. The amount of absorbed oxygen was calculated according to the pressure drop in this vessel. 

Fig. 3. Scheme of the circulation setup. 1) Vessel with oxygen 2) circulation pump 3) reaction vessel 4) traps 5) contact manometer 6) valve 7) vessel for measuring the absorption of oxygen 8 and 9) mercury manometers. 

The action of the manostat may be explained with the aid of Fig. II, 23, 6. Mercury is introduced into the container until the disc of the float just makes contact with the oriflce, when the pressure is equalised inside and outside the float. The device is connected to the pump and to the system by way of a large reservoir and a manometer. With the stopcock open, the pressure in the system is reduced by way of a by-pass between the pump and the system until the desired value as read on the manometer is reached, then both the stopcock and by-pass are... 

A strange accident occurred with ammonia. A mercury manometer was in contact with ammonia in the presence of water traces. The grey-brown solid formed detonated when a technician attempted to take it away mechanically. Tests showed that this solid did not form in the absence of water. 

Fig.4.3. Experimental arrangement for investigation of pyrolysis of molecules by the method of semiconductor sensors 1 - reaction vessel, 2 - quartz slab with a ZnO film (sensor), 3 - filter, 4 - contacts, 5 - incandescent filament, 6 - thermocouple, 7 - cell with a substance, 8 - lamp - manometer, 9 - pin, 10 - flask, 11 - sealing bulkhead, 12 - trap, 13 - thermostat.

The high mobility and tendency to dispersion exhibited by mercury, and the ease with which it forms alloys (amalgams) with many laboratory and electrical contact metals, can cause severe corrosion problems in laboratories. A filter-cyclone trap is described to contain completely mercury ejected accidentally by overpressuring of mercury manometers and similar items. 

The hlters must be designed and fastened to allow an easy removal to change the hlter and to keep a perfect peripheral airtightness. They must be provided with differential manometer to check them, (option equipped with maximum contact point). An obturable opening (+/- 100 mm) must be placed before the fan section to inject the DOP. The number of terminal hlters must be calculated to guarantee the same air velocity out of the... 

Toliani Test for detg the thermal stability of NG, NC, and NG propellants was first described in 1921(Ref 1). The app consists of a glass tube, in which 1.3 g of sample is placed, closed with a ground-glass top and connected with a paraffin trap, the top of which is connected to a Hg manometer. The entire app, except the manometer, is heated in a specially constructed oven at 120° for NG or NG contg propellants, and at 135° for NC. After 30 min of heating the sample, the stopcocks on the sample tube and on the manometer are closed to keep the sample in contact with its decompn products. The pressure developed is measured at suitable intervals and the index of stability adopted la the time in minutes necessary to attain a press of 100 or 300 mm Hg... 

Ammonia. Prolonged contact may yield explosive solid use of mercury manometers with NH3 should be avoided.2... 

Example In a mercury manometer, the level of mercury in contact with a reaction vessel is 70.0 mm lower than the level exposed to the atmosphere. 

The home-made heat-flow calorimeter used consisted of a high vacuum line for adsorption measurements applying the volumetric method. This equipment comprised of a Pyrex glass, vacuum system including a sample holder, a dead volume, a dose volume, a U-tube manometer, and a thermostat (Figure 6.3). In the sample holder, the adsorbent (thermostated with 0.1% of temperature fluctuation) is in contact with a chromel-alumel thermocouple included in an amplifier circuit (amplification factor 10), and connected with an x-y plotter [3,31,34,49], The calibration of the calorimeter, that is, the determination of the constant, k, was performed using the data reported in the literature for the adsorption of NH3 at 300 K in a Na-X zeolite [51]. 

Manometers connected across the venturi and the orifice contain a nonmisci-ble liquid (sp gr = 1.56) in contact with the liquid mixture The maximum possible reading on these manometers is 15 in. 

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