GB1589083A - Device - Google Patents

Description

(54) DEVICE (71) We, Arsons IIMITED, a British Company of Fison House, 9 Grosvenor Street, London WIX OAH, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to a dispensing device.

We have devised a form of reagent delivery device which reduces the problems encountered in handling corrosive and/or dangerous chemicals. The chemicals are dispensed from a reservoir without the chemical contacting the pump mechanism. Also the loss of pressure from the reservoir when the chemical has been dispensed provides a simple and effective indication as to when a desired amount of chemical has been dispensed.

The invention therefore provides a liquid dispensing device comprising a substantially airtight vessel (1) having an air inlet (4) connected to a pump means (7) and a liquid outlet (3) having its orifice located internally adjacent the base of the vessel (1) when in use and a pressure sensor (9) adapted to deactivate the pump means (7). The sensor detects a pressure drop in the vessel (1) which occurs when liquid therein has been substantially completely dispensed. Preferably the pump means is a motor driven pump, e.g. a diaphragm pump; the outlet is provided by a dip tube extending substantially the height of the vessel and having its orifice adjacent the base of the vessel; the vessel is provided with a substantially airtight closure means which preferably acts as the mounting means for the air inlet and the liquid outlet.

The dispensing device finds use as the reagent dispenser in a wide range of applications e.g. to dispense regeneration chemicals in an ion exchange column or water softener; and in dispensing additives to electroplating baths or to photographic processes.

The dispensing device finds especial use in combination with a tank in which the reagent dispensed is subsequently diluted, e.g. with water. The tank conveniently takes the form of a tank having sensors to detect when it is full and when it is empty and provided with a valved inlet for diluent, and is preferably located at a level above the reservoir to minimise the risk of siphoning. The dispenser device operates, e.g. on a timed basis, to feed a given quantity of reagent to the tank. Diluent is fed either simultaneously or subsequently to the tank until the full level sensor is actuated to switch off the diluent. The diluted reagent may now be withdrawn from the tank until the low level sensor is tripped to cause further reagent and diluent to be fed to the tank.

Such an assembly finds especial use where it is disired to dispense a large volume of a diluted reagent from a comparatively compact device and enables lower ratios of dilution, e.g. 1:1, 1:2 or 1:3, to be achieved than is possible with a conventional venturi mixer/diluter. A preferred form of the dilution device of the invention is shown diagrammatically in the accompanying drawing.

The device comprises a reservoir 1 for reagent (for example an acid reservoir) which takes the form of a replaceable or refillable vessel. For convenience reservoir 1 is provided by the Winchester or other flask in which the reagent is usually supplied. Alternatively, reservoir 1 could take the form of a plastic or similar tank which can be refilled with the desired quantity of reagent. The reservoir 1 has an outlet 2 at its top, e.g. the neck of the Winchester. Through the outlet 2 are passed a dip tube 3 which reaches to the base of the tank and an air supply tube 4. The outlet 3 is closed, e.g. by a bung 5 through which tubes 3 and 4 pass, to provide an airtight closure to the tank. The dip tube 3 passes to storage tank 6. The air tube 4 is connected to an air pump 7. Pump 7 is actuated by a timer swich 8 in response to signals from a level sensor in tank 6. When reagent is required in tank 6, e.g.

when the sensor detects that the tank is empty, pump 7 is started. This pumps air into reservoir 1 which discharges reagent through the dip tube. Air is pumped into reservoir 1 for a given time, thus displacing a given volume of reagent into tank 6. The pumping of reagent into tank 6 is repeated whenever the sensor in the tank is tripped, e.g. when the reagent is used, until the level of reagent in reservoir 1 drops below the end of dip tube 3. This causes a drop in pressure in reservoir 1 which trips a low pressure switch 9 switching off pump 7. The low pressure switch 9 may also be used to actuate an alarm if low pressure is encountered in the initial pumping periods due to leaks. A high pressure switch 10 may also be provided which is tripped at any time if pressure builds up due to a blockage in the system. It will be appreciated that fluctuations in pressure may occur during the initial stages of a pumping cycle and over-ride may be provided whereby signals from the pressure switches are ignored during the first 5 seconds of each cycle. It is also necessary that the low pressure due to an empty reservoir be distinguished from the low pressure due to a leak. This is conveniently achieved by a timer mechanism which acts during the initial period, say first 20 to 120 seconds, of the reagent dispensing cycle to trip an alarm if the low pressure switch is actuated.

As indicated above, it is preferred that tank 6 be provided with a valved feed 11 of diluent, e.g. mains water. The valve 12 on feed 11 is interlinked with pump 7 and a high level sensor 13 in tank 6. In this way diluent is fed to tank 6 only when undiluted reagent is being or has been fed to tank 6 and dilutes the reagent with a given volume of diluent.

WHAT WE CLAIM IS: 1. A liquid dispensing device comprising a substantially airtight vessel having an air inlet connected to a pump means and a liquid outlet having its orifice located internally adjacent the base of the vessel when in use and a pressure sensor adapted to deactivate the pump means.

2. A device as claimed in claim 1 wherein the pump means is a diaphragm pump.

3. A device as claimed in either of claims 1 or 2 wherein the outlet is provided by a tube extending substantially the height of the vessel and having its orifice adjacent the base of the vessel.

4. A device as claimed in any one of the preceding claims wherein the vessel is provided with a substantially airtight closure means which acts as the mounting means for the air inlet and the liquid outlet.

5. A device as claimed in any one of the preceding claims wherein the pressure sensor means is adapted to sense the drop in pressure when the contents of the vessel have been discharged.

6. A device as claimed in any one of the preceding claims in association with a second vessel adapted to receive liquid from the device and to dilute it with a diluent.

7. A device as claimed in claim 6 wherein the second vessel is provided with sensors adapted to detect when the level of liquid and diluent in that vessel reaches a given high or low level and to emit a signal adapted to actuate or de-activate the pump means.

8. A device as claimed in either of claims 6 or 7 in association with a second device as claimed in any one of claims 1 to 7, the operation of the devices being adapted to be interlinked whereby when one of the second vessels is being replenished, discharge of liquid from the other second vessel is halted.

9. A device as claimed in any one of the preceding claims in association with a timer means for controlling the duration of operation of the pump means.

10. A device for dispensing a liquid substantially as hereinbefore described with respect to and as shown in the accompanying drawing.

11. A reagent dispensing system incorporating a device as claimed in any one of the

Claims (1)

1. preceding claims.