(2) HEATING DEVICES.

Standard device with flow manostat for gas heating. This apparatus, which will be described in greater detail elsewhere, practically meters the gas to the burner jets at a steady rate of flow. The heat capacity of the burner and the associated parts is small; only a few minutes of operation is required to establish a state of steady output of heat to the boiling-vessel, provided that the calorific value of the gas is approximately constant. The apparatus is comprised of the following parts: Flow manostat.-The essential feature of the manostat, figure 91, is the balanced valve, V which floats in the orifices of the plates, OP, and is actuated by the float, F, which in turn is operated by changes in

FIGURE 91.-Flow manostat for gas pressure regulation.

The preferred form, as illustrated at A, has a double self-balancing valve which floats freely in the two gas orifices and does not close the openings completely at any level, as illustrated more clearly in the enlarged view C. A simpler form of regulator with a single, spring-balanced valve is illustrated in view B.

the level of the hydrostatic liquid in response to changes in the pressure of the regulated gas stream. The floating valve is retained in the centered position in the orifices of the plates OP by the bearing plates B (as lettered in the enlarged view, C). The valve-and-float assembly is further stabilized by the ballast weight, B (refer to views A and B). The liquid tank J, the float chamber with the gas outlet O and the top closure S, may be made of glass, as indicated, for the convenience of visibility of the moving parts during the adjustment and operation of the manostat. However, a simpler construction has proved amply satisfactory in service. The pointer, P, (view B) is convenient with either the single or the double valve [13].

Gas from the service pipe enters at I, and the regulated gas streams for two or three burners is taken off at O. Since the regulation of pressure is dependent in part upon a steady outflow at O, which is to

O 2 4 6 8 10

CENTIMETERS

FIGURE 92. Special star burner.

Vertical section, indicating the preferred form as constructed with water jackets and with a micrometeractuated needle valve which is readily removable for operation of the unit as a simple disk-nozzle injector. The, needle rests in a tapered socket in the micrometer spindle.

say, a steady consumption of gas by the burners, it follows that no change can be made in the number of burners without altering either their average individual output or else the adjustment of the regulator. Special star burners.-The essential feature of the form of gas burner which is to be used with glass beakers (but also is suitable for use with other types of boiling-vessel) is the arrangement of the multiple-flame jets upon the curved upper surfaces of the six rays, as indicated in the drawings, figures 92 and 93. Desirable but not indispensable features are, first, the unobstructed knife-edged disk nozzle for the injection of the gas into the mixing chamber, which

is readily removable for cleaning or exchange: and second, the watercooling of the nozzle chamber and nozzle and the mixing chamber. [13] The disk nozzles are to be properly formed of corrosion-resistant material, such as monel metal or stainless steel. A number of interchangeable nozzles with assorted diameters of orifice should be provided to facilitate adjustment of the burner output. For a given rate of discharge, the orifice of a thin disk nozzle presents maximum clearance for the flow of gas and minimum probability of clearance contraction through accumulation of dirt, tar, or polymerization waxes. Hence the disk nozzle provides stability and reliability of heat out

FIGURE 94.-Stove assembly with the burner arrangement illustrated in Figure 4. To indicate the correct relations among the beaker, burner, and top plate, the operating position of the boiling-vessel assembly is illustrated in broken outline. WI represents the water inlet, WO the water outlet, and GI the gas inlet.

put by the burner. At some sacrifice of these features, but at little sacrifice of accessibility for cleaning when deposits appear, provision can be made for adjustment of the output capacity of a burner with disk nozzle by installing in the nozzle chamber a long-taper needle valve with a maximum thrust diameter somewhat less than the

FIGURE 95.-Stove assembly with the burner arrangement illustrated in Figure 5. The boiling-vessel assembly is in position for the carrying out of a candy test.

diameter of the orifice, which it is arranged to penetrate concentrically. The arrangement is indicated in figure 92.

In figures 92 and 94 the nozzle chamber into which the gas inlet, GI, leads is enveloped by its water jacket, H1, through which the current of water passes from its inlet, II, to the transfer duct leading to the mixing-chamber water jacket, H2, whence it flows to waste through the outlet, WO. By means of the vertical adjustment provided for the nozzle chamber assembly, the cap, C, can be brought to