Patent GB-720161-A (GB)
Title: Improvements relating to the sampling of liquids
Inventor: DOWD ARTHUR
IPC: G01N1/14
Filed: 1949-05-24
Abstract: 720,161. Sampling liquids. LONDON COUNTY COUNCIL. Aug. 24, 1950, [May 24, 1949; Jan. 20, 1950], Nos. 13904/49 and 1580/50. Class 106 (5). [Also in Group XXVIII] Apparatus for sampling liquids such as sewage comprises a pipe circuit connecting the source of liquid supply to a sample-receiving vessel or vessels, and control means operated by timing mechanism to effect automatically a sequence of air pressure changes in the circuit at predetermined intervals to deliver measured quantities of the liquid to the vessel or vessels.. In the arrangement shown in Fig. 1, a pump 4 draws upwards a supply of liquid from a sewer through a pipe 2 to a container 1 and any over-flow passes into a chamber 7. When the pump is stopped automatically by the action of a liquid-level contact 8a the container is connected to atmosphere and the measured sample therein siphons into a storage container 8. Electrical means operate the apparatus automatically at predetermined intervals. This arrangement may be modified by connecting each of a number of such units, Fig. 2 (not shown), by a suction pipe to a particular point in the sewer and through an automatic valve to a common pump, and an electrical control sets the units automatically into operation in the desired sequence and at fixed or variable intervals. The further modification shown in Fig. 3 comprises two containers 16, 17 connected by a syphon 18, the container 16 being connected through an automatic valve 21 to the inlet and outlet pipes of a pump 22. An electrical control starts the pump and operates the valve so as first to cause pressure'to clear the system and then to apply suction to charge the container 16 until a liquid-level contact 16a again operates the valve to apply pressure whereby the sample in the container 16 syphons into the container 17. The cycle is automatically repeated at pre-determined times and if desired a battery of the units may be connected and operated as described above in connection with the modified form of Fig. 1. In the arrangement shown in Fig. 5 a sample receiver 40 is connected with a pump 62 through a pipe 45 controlled by an automatic valve 46 which is set first to apply pressure to clear the system and then suction to charge the receiver through a suction pipe 51 fitted with a splash guard 52. A liquid-level contact 60 stops the pump and the measured sample then siphons through pipes 53, 54 to storage and surplus storage containers 55, 56, this action being assisted if desired by the automatic opening of a valve 65 in the receiver 40. The receiver 40 may have an overflow compartment 41 and associated storage container 49. The apparatus shown in Fig. 6 comprises four containers 77, 78, 79, 80 which are automatically filled in succession at pre-determined intervals, being arranged in circuits by-passing a control vessel 70 and controlled by automatic valves 89, 90, 91, 92. The vessel 70 is connected with the sewer by a pipe 71 and with a pump 74 by an automatic valve 73 which is controlled in much the same way as is the valve 21, Fig. 3. The valves 89, 90, 91, 92 are automatically operated in co-operation with the valve 73 to provide for successive filling of the respective containers, a liquid-level contact 93 being fitted in the vessel 70. In the modified arrangement shown in Fig. 7 four containers 98, 99, 100, 101 are carried by a turntable 110 which is intermittently rotated under automatic timed control and raised by wedges, screws or cams 111 to bring each container in turn into air-tight engagement with a cover 104 through which a pipe 109 leads via an automatic valve 108 to a pump 103. With a container in engagement with the cover 104, the pump is started and the valve set first to apply pressure, then suction to charge the container, and finally, by the action of a liquid-level contact 105, again to apply pressure; the pump is then stopped and the turntable lowered and rotated to position the next container in readiness for the next cycle which follows automatically. This arrangement may be further modified by mounting a chamber in fixed position above the turntable and connecting it with the suction pipe, pump and automatic valve; a siphon pipe depends from the chamber through a seating against which each container is raised in turn into air-tight relation in the course of a complete cycle. When the sewage is led to both receiving and storage containers, the suction pipe from the sewer may be led to either the top or bottom of the receiving container and the two containers may be connected either at top or bottom. If desired, the suction pipe when led to the bottom of the receiving container may have a branch which leads upwardly to enter the storage container either at the top or bottom, the pipe being continued upwardly for a distance in the storage container in the latter case and the two containers being connected at the top by a non-return valve. The frequency and/or quantity of the samples may be weighted according to the rate of flow in the sewer.