Liquid head control system

• US 4,106,671 A
• Filed: 03/21/1977
• Issued: 08/15/1978
• Est. Priority Date: 10/31/1975
• Status: Expired due to Term

• Current Assignee: Beckman Instruments, Inc. (Danaher Corporation)
• Original Assignee: Beckman Instruments, Inc. (Danaher Corporation)
• Inventors: Sharples, Thomas Davy
• Primary Examiner(s): Reeves, Robert B.
• Assistant Examiner(s): Rolla, Joseph J.
• Application Number:
  US05/779,379
• Time in Patent Office: 512 Days
• Field of Search: 222/52, 222/56, 222/61, 222/64, 222/69, 222/394, 222/396, 222/399, 222/1, 222/14, 222/66, 222/67, 222/68, 137/209, 137/386, 250/577
• US Class Current: 222/61
• CPC Class Codes: G01N 1/38 Diluting, dispersing or mixing samples
• CPC Class Codes: G01N 2035/1025 Fluid level sensing
• CPC Class Codes: G01N 35/00 Automatic analysis not limited to methods or materials provided for in any single one of groups G01N1/00 - G01N33/00; Handling materials therefor
• CPC Class Codes: G01N 35/1002 Reagent dispensers
• CPC Class Codes: Y10T 137/7287 Liquid level responsive or maintaining systems

Abstract

An automatically controlled liquid dispensing system including a reagent dispenser adapted to function as an intermediate container for dispensing relatively small controlled volumes of liquid to an associated receiving system in a continuous "demand" mode, this dispenser being indirectly monitored to be automatically and continually replenished after liquid is withdrawn therefrom, using a simple photoelectric liquid level monitor system including a fail-safe overflow control arrangement.

Claims

1. In an improved automatic liquid dispensing system including a closed storage vessel for holding a prescribed volume of liquid to be dispensed to a use point in selectable dosages and upon demand, said closed storage vessel having a bottom, the combination therewith of:

an intermediate dispensing system including a closed transfer vessel hydraulically coupled between said storage vessel and said use point, said transfer vessel being designed to hold a fraction of the liquid capacity of said storage vessel;

an automatic replenishment control means adapted to automatically control the transfer of said liquid from the storage vessel to the transfer vessel; and

a pneumatic drive means comprising controlled gas pressurizing means and controlled gas venting means for placing a pressurized gas supply in pneumatic communication with said storage vessel sufficient to effect said replenishment in response to prescribed replenishment signals from said control means; and

wherein said automatic replenishment control means comprises a liquid level detecting sub-system comprising a riser tube having one end terminating adjacent the bottom of said storage vessel and the other end opening to the atmosphere, a plurality of detect units for detecting the presence of liquid at a minimal and other prescribed hydraulic reference levels in said riser tube, said detect units being mounted adjacent said riser tube;

wherein each unit is coupled to apply signals to manipulate said control means; and

wherein some of said signals are adapted to enable said gas pressurizing means and other of said signals are adapted to enable said gas venting means.

2. The combination as recited in claim 1 wherein said detect system comprises at least three photoelectric detectors designed and arranged to generate solenoid-enabling signals, a first detector adapted to issue first signals enabling the coupling of said pneumatic drive means to said storage vessel, sufficient to drive liquid therefrom to said transfer vessel until the sensed liquid level exceeds a prescribed "near-full" level;

a second detector adapted to issue second signals enabling the coupling of pneumatic vent means to said storage vessel when said liquid level reaches a prescribed "over-flow" level; and

a third detector adapted to issue third signals enabling the coupling of pneumatic vent means to said storage vessel as well as invoking emergency alarm conditions and the disablement of said drive means until reset, as long as the liquid level sensed thereby exceeds a prescribed "over-flow" level.

3. An automatic liquid dispensing apparatus comprising:

a closed storage vessel for containing a large quantity of liquid and having a bottom;

a first pressurizing means including a valve means connected to said storage vessel for controllably pressurizing said vessel;

a closed intermediate vessel for containing a small quantity of liquid and having a bottom, said intermediate vessel being located remote from said storage vessel;

an inlet fluid conduit means having one end terminating adjacent the bottom of said storage vessel and the other end connected adjacent the bottom of said intermediate vessel;

an outlet fluid conduit means having one end terminating adjacent the bottom of said intermediate vessel and the other end defining a discharge point;

second pressurizing means connected to said intermediate vessel for periodically pressurizing said vessel to expel liquid therefrom;

fluid control means between said intermediate vessel and said storage vessel for allowing passage of liquid from said storage vessel to said intermediate vessel when the head pressure in said storage vessel is greater than the head pressure in said intermediate vessel and restricting passage of said liquid from said intermediate vessel to said storage vessel when the head pressure in said intermediate vessel is greater than the head pressure in said storage vessel;

a riser tube having one end terminating adjacent the bottom of said storage vessel and the other end opening to the atmosphere;

a pair of spaced apart, liquid detecting means associated with said riser tube each generating an electrical signal in response to the liquid passing a given height in said riser tube;

electrical circuit means connected between said pair of liquid detecting means and said valve means for pressurizing said storage vessel in response to one of said electrical signals and venting said storage vessel in response to the other of said electrical signals.

4. The automatic liquid dispensing apparatus as defined in claim 3 further comprising:

third liquid detection means associated with said riser tube for generating a third electrical signal in response to the liquid passing a height in said riser tube indicating an over pressurized condition of said storage vessel and electrically connected to said electrical circuit means;

said electrical circuit means operative in response to said third electrical signal for venting said storage vessel and preventing operation of said valve means in response to the other of said electrical signals until reset.

5. An automatic liquid dispensing apparatus comprising:

a pressurizing means including a valve means connected to a storage vessel for controllably pressurizing said vessel, said storage vessel having a bottom;

an outlet fluid conduit means having one end terminating adjacent the bottom of said storage vessel and the other end defining a discharge point;

a riser tube having one end terminating adjacent the bottom of said storage vessel and the other end opening to the atmosphere;

a pair of spaced apart, liquid detecting means associated with said riser tube each generating an electrical signal in response to the liquid passing a given height in said riser tube; and

electrical circuit means connected between said pair of liquid detecting means and said valve means for pressurizing said storage vessel in response to one of said electrical signals and venting said storage vessel in response to the other of said electrical signals.

6. The automatic liquid dispensing apparatus as defined in claim 5 further comprising:

third liquid detection means associated with said riser tube for generating a third electrical signal in response to the liquid passing a height in said riser tube indicating an over pressurized condition of said storage vessel and electrically connected to said electrical circuit means;

said electrical circuit means operative in response to said third electrical signal for venting said storage vessel and preventing operation of said valve means in response to the other of said electrical signals until reset.