Patent GB-428486-A (GB)
Title: Improvements relating to apparatus for delivering water or other liquids in measured quantities
IPC: G01F11/10
Filed: 1934-01-24
Abstract: 428,486. Delivering measured quantities of liquid; regulating liquid levels. BOARD OF TRADE, SECRETARY OF, Great George Street, and BOYS, C. V., 66, Victoria Street, both in London. Jan. 24, 1934, No. 2523. [Classes 106 (v) and 123 (i)] [See also Group XX] Apparatus for delivering accurately measured quantities of liquid from a reservoir comprises a power driven rotary measuring carrier 10 bearing one or more receptacles including a measuring tube 42 which is filled with liquid at each revolution of the carrier and measures the main part of each quantity and an adjusting tube 43 which is of smaller cross section and is in communication with the measuring tube and which receives a smaller amount of liquid necessary to ensure that the quantity picked up varies accurately in accordance with the liquid level in the reservoir. The invention is described as applied to apparatus for supplying cooling water for a gas calorimeter. Each measuring tube is connected through its adjusting tube with a pitcher 44 so that during rotation the measured quantity picked up by the measuring and adjusting tubes is delivered to the pitcher and then emptied into a trough 46 from which it flows away to the calorimeter, The tank 32 from which the water is picked up is constantly supplied with a slightly greater quantity of water from a reservoir 36 by means of dipping vessels 39 and the level in the tank 32 is regulated by means of a siphon 28 carried from a balance arm 11, the other end of which carries by knife edges 20 an elongated air bell 18, the lower end of which is immersed in mercury and also a pointer 16 moving over a fixed scale 17 graduated in terms of the gas volume factor. The balance arm also carries an adjustable balance weight 22 and an antigravity bob 24 adjustable along a screw support 25 and arranged to counteract the stability due to the siphon and its supports and caused also by the immersion of the lower end of the air bell. To set the apparatus a stop cock 19 at the upper end of the air bell is opened, the pointer 16 placed so as to read correctly the current gas volume factor and a cock 19 is then closed. Subject to certain conditions set out below the water level in the tank will vary inversely with respect to the gas volume factor. If the amount of water picked up is also to vary inversely as the gas volume, then the measuring and adjusting tubes are shaped as shown in Fig. 3. The point O represents the axis of rotation of the carrier, P the centre of curvature of the tube 43 and B the mid-point of the tube 43. Distances OA, OB and OP are equal and the angles AOP and AOB are right angles. The differences between the lines Ob and Oc and the lines Ob and Od represent the variations of water level in the tank 32 above and below the standard, that is a level a distance Ob below the axis of the carrier, for producing variations in the quantity picked up by a measuring receptacle equal to the contents of the tube 43 between the points B and C and the points B and D. By varying the shape and dimensions of the measuring and adjusting tubes the amount of water picked up can be made any desired function of the water leve'. The siphon has an upturned mouth which, to avoid capillarity effects is surrounded by a U-shaped strip of glass or metal. For the correct working of the apparatus, three conditions must be fulfilled. Firstly, the distance from the axis of rotation O to the tip of the pointer 16 when it reads 1.000 on the scale is half the length of the air column in the bell. Secondly, the angle at the axis O between straight lines drawn from the centre of the upturned mouth of the siphon and from the knife edges 20 is 135‹. Thirdly, the radius of motion of the siphon mouth is equal to the radius OA of the measuring carrier.