Manostats Cartesian

An excellent manostat, based on the Cartesian diver principle, is marketed under the name of Cartesian manostat. 

The commercial form of Cartesian manostat, model 7A, is depicted in Fig. II, 23, 7 it is normally charged with mercury except for very low pressures when di-w-butyl phthalate is employed. The manostat is highly sensitive in its action furthermore, once the pressure has been set in the instrument, the system may be shut down without disturbing the setting. 

Supplied by The Emil Greiner Co. of New York and by Edwards High Vacuum Ltd. an all.metal Cartesian manostat is also marketed. 

The amount of water adsorbed after the samples were outgassed was controlled by adjustment of the pressure in one of three ways use of a sensitive Cartesian diver manostat, use of a water source at a controlled temperature, or use of the mixed magnesium perchlorate hydrates mentioned above. The amount of water adsorbed by the sample was measured either by the gain in weight of a companion sample or by interpolation from the isotherm at 23.5° C. The heat of immersion of samples with no water adsorbed was determined with samples sealed off from the vacuum line while they were still in the furnace at 500° C. 

The pressure of the system was controlled to within 0.5 mm Hg for each series by a Cartesian diver manostat connected to a positive air leak, a vacuum pump, and a surge volume of 12 liters. An absolute mercury-in-glass manometer with a 0.1 mm sliding vernier was used to measure the pressure. Temperatures were monitored via two copper-constantan thermocouples one was located just above the liquid surface and the other just below it. Maximum differences of 0.4°C were detected, but an average of the two readings was reported to 0.2°C. Glacial acetic acid and acetone, both meeting ACS specifications, were used. 

The Cartesian manostat is a device used to maintain the pressure in a partially evacuated sytem to within about 1% of some previously determined value. 

The theory governing the functioning of Cartesian diver manostats, and a number of modifications of the device, are dealt with by Gilmot. " ... 

CHAPTER 9. ADVANCED GLASSBLOWING Glassworking Lathes Basic Operations Cartesian Manostat A Mercury Diffusion Pump References... 

The Cartesian manostat consists of a diver which moves up and down depending on the pressure of the distillation system, a means of setting the pressure in the diver, and a capillary which engages the short rubber stopper at the top of the diver. The body of the mano-... 

Figure 1 is a schematic diagram of the system used in this study. The system pressure was controlled with a Cartesian Manostat 6A (Mano-stat Corporation) and a Welch mechanical pump Model 1402 (W. M. Welch Manufacturing Company). The discharge was initiated and sustained with a 7,000/12,000 volt Jefferson luminous tube outdoor-type transformer (Jefferson Electric Company) connected to a 60-c.p.s. 110-volt power source through a Variac variable transformer. 

A manostat (one pressure) is a device for maintaining any pressure desired from 760 to 2 torr with an accuracy of 1 to 2 torr. Suppose you had prepared /w-nitrotoluene and wanted to purify it. At 20 torr, the compound boils at 112.8 C. How can you maintain a pressure of 20 torr in your system during the entire distillation so that you can be sure that you collect only the pure material A manostat is a device that allows you to do this. The two most common types are the Cartesian diver and the Lewis-Nester. 

In addition to these considerations, it is necessary to make provisions for controlling and measuring the vacuum produced by the pump this requires that a manostat and a manometer be incorporated into the system. Excellent Cartesian diver manostats are available commercially at reasonable prices ca. 50), and these and the Lewis manostat (Fig. 2-20) are very satisfactory for most organic distillations since pressure variations within the system will be very small during their operation. It is desirable to protea the manostat from the system with a Dry Ice trap to avoid fouling of the mercury by contact with organic vapors. 

A manostat device (there are several cheap commercial models based on the Cartesian diver) set to regulate the suction to the filtration unit to prevent the vacuum becoming greater than 300-350 mm of mercury. 

Note A4.1—If a solenoid valve or other electrically operated regulator is used, a suitable manostat is required for activation of the regulating device. Many such manostats are described in the literature or are available from laboratory supply houses. As an alternative for the separate manostat and solenoid, a Cartesian Manostat can be used. This device is capable of maintaining the system pressure within the specified limits down to a pressure of about 1 kPa. 

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