Flow indicator for positive displacement pump

• US 4,257,748 A
• Filed: 01/02/1979
• Issued: 03/24/1981
• Est. Priority Date: 01/02/1979
• Status: Expired due to Term

• Current Assignee: PMC Incorporated (PMC Global Incorporated)
• Original Assignee: Venus Products Incorporated
• Inventors: Ives, Frank E., Nash, Terrence G.
• Primary Examiner(s): Croyle, Carlton R.
• Assistant Examiner(s): Look, Edward
• Application Number:
  US06/000,573
• Time in Patent Office: 812 Days
• Field of Search: 417/63, 417/557, 417/540, 91/1, 92/5, 222/40, 222/155, 116/228, 73/307, 73/319, 285/161, 285/206, 285/39
• US Class Current: 417/63
• CPC Class Codes: G01F 1/375 with mechanical or fluidic indication
• CPC Class Codes: G01F 23/02 by gauge glasses or other apparatus involving a window or transparent tube for directly observing the level to be measured or the level of a liquid column in free communication with the main body of the liquid

Abstract

A flow indicator for a positive displacement pump is connected to a liquid supply reservoir below the liquid level in the reservoir. The indicator has a first passage through which liquid is supplied from the reservoir to the inlet of the pump. The first passage has an inlet below the liquid level in the reservoir and an outlet coupled to a supply conduit in turn coupled to the pump inlet. A restrictor is positioned in the first passage adjacent the inlet to partially restrict fluid flow through the passage. A secondary passage is coupled in fluid communication with the first passage downstream from the restrictor. A transparent tube is coupled to the secondary passage and extends upwardly alongside the reservoir to a location above the liquid level in the reservoir. A float is slidably positioned in the transparent tube. When the pump is not operating or is functioning on a return stroke, as opposed to a suction stroke, the liquid level in the tube seeks the same as the liquid level in the reservoir, thereby positioning the float adjacent the liquid level in the reservoir. When the pump draws liquid from the reservoir through the flow indicator, the restrictor is sized so that only a portion of the liquid is drawn from the reservoir, while the remaining liquid is drawn through the secondary passage from the transparent tube. As liquid is drawn from the reservoir and the transparent tube, the liquid level in the tube lowers, causing the float to visibly drop within the tube. The restrictor is sized so that during the return stroke of the pump liquid flows from the reservoir into the transparent tube, returning the liquid level in the tube and thus the float to the same level as the reservoir liquid level.

Claims

1. In a fluid supply system including a source of liquid to be pumped and a positive displacement liquid pump, an improved flow indicator for a positive displacement pump comprising:

first means defining a first passage, said first passage having an inlet and an outlet, said inlet being adapted for coupling to said source of liquid to be pumped, said outlet being adapted for connection to the inlet of said positive displacement liquid pump,

second means defining a second passage having an inlet and an outlet, said second means being at least partially transparent, said outlet being open to the atmosphere at a position above the surface of said source of liquid, said inlet being in fluid communication with said first passage at a location between the inlet and outlet of said first passage,

restriction means in said first passage for partially restricting flow through said first passage, said restriction means being located between the inlet to said first passage and the location at which said second passage is in fluid communication with said first passage, and

float means movably positioned in said second passage for movement along said passage in reaction to a variation in fluid level in said second passage.

2. The indicator of claim 1 further comprising:

filter means connected to said first means at a location upstream from the inlet to said first passage for inhibiting the introduction of foreign material into said first passage.

3. The indicator of claim 2 wherein said first means comprises a body through which said first passage extends, said conduit having an external shoulder facing in the direction of the inlet to said first passage, said source of liquid comprising a reservoir having a wall through which at least a portion of said body extends, said indicator further comprising:

seal means associated with said shoulder for abutting said wall in sealing relationship through which said conduit extends.

4. The indicator of claim 2 wherein said body has external threads adjacent said first inlet, said filter means comprising:

an internally threaded nut having an outwardly flared passage that extends away from the inlet to said first passage when said nut is threaded onto said body, and

a filter element positioned in said flared passage.

5. The indicator of claim 1 wherein said second means comprises a transparent tube, said float being movably mounted in said tube, said second means further comprising a passage in said body having one end communicating with said first passage and a second end opening outwardly from said body, said second end being sized to receive an end of said tube.

6. In a fluid supply system including a reservoir having a sidewall, a bottom and a top, and a positive displacement pump having an inlet, the improvement comprising:

a fitting including means defining a first passage having an inlet and an outlet, said fitting being adapted to extend through an opening in the sidewall of said reservoir adjacent the bottom of said reservoir so that the inlet to said first passage is located inside the reservoir below the level of liquid in said reservoir, and so that the outlet from said first passage is located exterior of said reservoir, said fitting being constructed so that said outlet is adapted for fluid coupling to the inlet of said pump,

means for securing said fitting to said sidewall,

a transparent conduit extending upwardly from said fitting, said fitting including means defining a second passage having an outlet located externally from said reservoir and being sized to receive the lower end of said conduit in sealed relationship, the upper end of said conduit being located above the fluid level in said reservoir, said second passage being in fluid communication with said first passage at a location upstream from the outlet from said first passage,

a float slidably positioned in said tube for floating movement in reaction to a change in liquid level in said tube,

restriction means associated with said first passage upstream from the junction of said first and second passages for restricting the flow of liquid through said first passage.

7. The improvement of claim 6 further comprising:

filter means associated with said fitting upstream of said inlet to said first passage.

8. The improvement of claim 6 wherein the outlet from said fitting is adapted for coupling to a conduit in turn adapted for coupling to he inlet of said pump.

9. The improvement of claim 6 wherein said reservoir has an opening through a wall thereof located above the liquid level in said reservoir, said tube extending through said opening, said outlet from said tube being located inside said reservoir and being vented to the atmosphere.