[Illustration: FIG. 7.--TYPICAL FORMS OF VENT-PIPES OR SAFETY-VALVES.]
A refinement upon this vent-pipe is represented at C, where it is rigidly
fastened to the tank of the holder, and has its internal aperture always
above the level of the water in the apparatus. Rigidly fixed to the crown
of the bell is a tube of wider diameter, _h_, which is closed at its
upper end. _h_ is always full of gas, and its mouth is normally
beneath the level of the water in the seal; but when the bell rises to
its highest permissible position, the mouth of _h_ comes above the
water, and communication is opened between the holder and the outer
atmosphere. No water enters the vent-pipe from the holder, and therefore
no gurgling or irregular pressure is produced. Another excellent
arrangement of a vent-pipe, suggested by Klinger of Gumpoldskirchen, is
shown at D, a drawing which has already been partly considered as a
washer and water-seal. For the present purpose the main vessel and its
various pipes are so dimensioned that the vertical height _g_ to
_f_ is always appreciably greater than the gas pressure in the
service or in the generator or gasholder to which it is connected.
Pages:
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244