Air-operated eductor control

Claim 2

In an air lift pump: an upright eductor pipe disposed with its open lower end submerged in a body of liquid; compressed air supply means; an air supply line connecting said air supply means with the lower submerged end of said eductor pipe; means associated with said air supply line at a location between said air supply means and said submerged end of said eductor pipe for closing said line when air is not being Supplied from said air supply means and for automatically passing air through said line to said submerged end of said eductor pipe when air is supplied from said air supply means whereby the pressure in said line is proportional to the static pressure head of liquid acting on the submerged end of said eductor pipe plus the pressure of the air, if any, being supplied from said air supply means; and a control system associated with said air supply means for starting operation of the air lift when the liquid surrounding said eductor pipe rises to a predetermined high level and for stopping operation of the air lift when the liquid surrounding said eductor pipe falls to a predetermined low level, said control system including means responsive to a predetermined first pressure in that portion of said air supply line between said submerged end of said eductor pipe and said cloying means initiating flow of compressed air into said supply line and responsive to a subsequent predetermined second pressure in said supply line for stopping the flow of compressed air into said supply line, said predetermined second pressure being higher than said first pressure and lower than the pressure which exists in said supply line upon initiation of air flow thereinto.

Claim 3

Apparatus as in claim 1 wherein said control system includes additional pressure responsive means for flowing compressed air into said air supply line when a predetermined third pressure lower than said first pressure exists in said air supply line whereby a reduction in pressure in the latter due to outward leakage of air will cause said air lift to operate.

Claim 4

Apparatus as in claim 1 wherein said pressure responsive means includes a first device operative to flow compressed air into said air supply line when activated by a pressure equal to or greater than said predetermined first pressure, and a second device operative to flow compressed air into said air supply line when activated by a pressure equal to or greater than said predetermined higher pressure and operative to stop the flow of compressed air when deactivated by a pressure below said second pressure, said control system further including timing means for deactivating said first device a short time after it has been activated by said first pressure whereby said second device maintains air flow until said second pressure is effected in said air supply line.

Claim 5

Apparatus as in claim 3 wherein said control system includes a third pressure responsive device operative to flow compressed air into said air supply line when activated by a predetermined third pressure in the latter which is less than said first pressure whereby reduction of pressure in said supply line resulting from outward leakage of air will cause said air lift to operate.

Claim 6

An air lift pump for periodically pumping out a wet well or the like and a control system for operating said air lift upon a rise in the liquid in the wet well to a predetermined level comprising: an upright eductor pipe disposed with its lower end submerged in the liquid; blower means for generating compressed air; a compressed air supply line connecting said blower means with the lower submerged end of said eductor pipe; one-way valve means in said supply line for passing compressed air to said eductor pipe when said blower means is operating and for sealing said supply line when said blower means is not operating whereby the pressure in said supply line on the downstream side of said valve means is a measure of the level of the liquid surrounding said eductor pipe when said blower means is operating and when said blower means is not operating; an electrical control circuit which when energized operates said blower means; a first pressure responsive device associated with said supply line downstream of said valve means, said first device being activated by a pressure increase in said supply line to a predetermined first pressure occasioned by a rise in the liquid level surrounding said eductor pipe; means responsivE to activation of said first device to energize said control circuit; a second pressure responsive device associated with said supply line downstream of said valve means, said second device being activated by a further increase in pressure in said supply line occasioned by operation of said blower means and being deactivated by a decrease in pressure in said supply line to a second predetermined pressure which is higher than said first predetermined pressure, said pressure decrease being occasioned by a drop in the liquid level surrounding said eductor pipe as said air lift operates; means responsive to activation and deactivation of said second pressure responsive device for energizing and deenergizing said control circuit; and means for deactivating said first pressure responsive device after said second pressure responsive device has been activated whereby said control circuit remains energized until the pressure in said supply line falls to said second predetermined pressure.

Claim 7

An air lift pump for periodically pumping out a wet well or the like and a control system for operating said air lift upon a rise in the liquid in the wet well to a predetermined level comprising: an upright eductor pipe disposed with its lower end submerged in the liquid; blower means for generating compressed air; a compressed air supply line connecting said blower means with the lower submerged end of said eductor pipe; one-way valve means in said supply line for passing compressed air to said eductor pipe when said blower means is operating and for sealing said supply line when said blower means is not operating whereby the pressure in said supply line on the downstream side of said valve means is a measure of the level of the liquid surrounding said eductor pipe when said blower means is operating and when said blower means is not operating; an electrical control circuit which when energized operates said blower means; a first pressure responsive device associated with said supply line downstream of said valve means, said first device being activated by a pressure increase in said supply line to a predetermined first pressure occasioned by a rise in the liquid level surrounding said eductor pipe; means responsivE to activation of said first device to energize said control circuit; a second pressure responsive device associated with said supply line downstream of said valve means, said second device being activated by a further increase in pressure in said supply line occasioned by operation of said blower means and being deactivated by a decrease in pressure in said supply line to a second predetermined pressure which is higher than said first predetermined pressure, said pressure decrease being occasioned by a drop in the liquid level surrounding said eductor pipe as said air lift operates; means responsive to activation and deactivation of said second pressure responsive device for energizing and deenergizing said control circuit; and means for deactivating said first pressure responsive device after said second pressure responsive device has been activated whereby said control circuit remains energized until the pressure in said supply line falls to said second predetermined pressure.

Claim 8

Apparatus as in claim 5 wherein said means for deactivating said first pressure responsive device includes timing means operable to deactivate said first pressure responsive device after said second pressure responsive device has been activated.

Claim 9

Apparatus as in claim 6 wherein said timing means is connected to said first pressure responsive device so as to begin timing upon activation of said first pressure responsive device.

Claim 10

Apparatus as in claim 5 including a third pressure responsive device associated with said supply line downstream of said valve means, said third device being activated by a lower pressure in said supply line than said first predetermined pressure to energize said control circuit, whereby undesired air leakage out of said supply line and consequent loss of pressure therein during a period when said blower means is not operating will energize said control circuit.

Claim 11

Apparatus as in claim 1 wherein said means for closing said air supply line and for subsequently passing air therethrough includes a one-way valve in said air supply line.