Fig. 148.—Gauge Weir Penstocks.
Various types of measuring appliances are in use. Among these the simplest is the gauge weir penstock [Fig. 148], manufactured by Messrs. Adams Hydraulics, Ltd., from which the depth of water flowing over the weir can be observed at any time. This, however, does not provide a record of the volume flowing at all times. For this purpose the same firm supply several types of recorders, among which the simplest is the type shown in [Fig. 149]. This is supplied with 24-hour or 7-day movement, and charts which register the volume in gallons per minute, per hour, or per 24 hours.
Fig. 149.—Recording Apparatus.
Another measuring apparatus is that supplied by Messrs. George Jennings, Ltd., [Fig. 150]. This consists briefly of a hollow copper float attached to a brass rod, which is carried up through a hollow column into the indicator box provided with a glass hinged door. The brass rod is provided with pointers, which move up and down with the rods and indicate the water level.
Fig. 149a.—Volume Recorder.
Messrs. George Kent, Ltd., supply a large number of various types of recorders and measuring instruments, including the well-known “Venturi” meter and others actuated by floats to indicate the discharge over a weir. The Venturi meter type of measuring apparatus adapted for sewage, is shown in [Fig. 151]. In this case the Venturi tube may form part of the ordinary supply pipe, or it may be fitted in a chamber built in the supply channel, the tube connected through the chamber with its ends terminating in the channel at either side. This measuring apparatus may be fitted with the following types of recorders. A diagram only, counter only, or combined counter and diagram in one instrument. The recorder may be placed in any convenient position within a thousand feet of the meter tube.