Method and apparatus for preventing electrostatic fields in large tanks

Claim 3

A method according to Claim 1, wherein said negative-charge-forming fluid is clean salt water.

Claim 4

A method according to Claim 2, wherein said positive-charge-forming fluid is a mixture of water with oil.

Claim 5

A method according to Claim 3, further comprising the steps of measuring the electrostatic field created by said jet; and controlling said mixture in order to maintain a neutral electrostatic field.

Claim 6

In cleaning operations for mammoth tank ships, wherein a high-velocity jet is employed to wash down the walls of a tank and the washing fluid is collected in a sump, the method comprising withdrawing said washing fluid from the sump; separating said washing fluid into heavier and lighter components; and remixing said components and controlling the relative amounts of each in said jet in order to produce an electrically neutral atmosphere in said tank.

Claim 7

In cleaning operations for mammoth tank ships, wherein a high-velocity jet is employed to wash down the walls of a tank and the washing fluid is collected in a sump, the method comprising withdrawing said washing fluid from the sump; separating said washing fluid into heavier and lighter components; and remixing said components and controlling the relative amounts of each in said jet in order to produce an electrically neutral atmosphere in said tank.

Claim 8

In cleaning operations according to Claim 5, the method further comprising measuring the electrostatic charge of said atmosphere; and controlling said relative amounts in accordance with said measurement.

Claim 9

In mammoth tanker tank-cleaning, a system for preventing electrostatic charge build-up, comprising in combination jet nozzle means for forming a high-velocity fluid jet to be directed against the walls of said tank; pump means for forcing a cleaning fluid through said nozzle; said cleaning fluid having at least two components; one of said components tending to form a negative electrostatic field and the other tending to form a positive electrostatic field; and means for regulating the relative percentages of said two components in order to maintain a neutral electrostatic field in said tank; said last named means comprising a mixing valve; means for determining the electrostatic field potential in said tank; and means for actuating said mixing valve in response to said electrostatic potential so as to reduce said potential toward zero.

Claim 10

In mammoth tanker tank-cleaning, a system for preventing electrostatic charge build-up, comprising in combination jet nozzle means for forming a high-velocity fluid jet to be directed against the walls of said tank; pump means for forcing a cleaning fluid through said nozzle; said cleaning fluid having at least two components; one of said components tending to form a negative electrostatic field and the other tending to form a positive electrostatic field; and means for regulating the relative percentages of said two components in order to maintain a neutral electrostatic field in said tank; said last named means comprising a mixing valve; means for determining the electrostatic field potential in said tank; and means for actuating said mixing valve in response to said electrostatic potential so as to reduce said potential toward zero.

Claim 11

A system according to Claim 7, further comprising a sump for collecting run-off fluid from said cleaning; means for separating said run-off fluid into said two components; and means for supplying said separated components to said mixing valve.

Claim 12

A system according to Claim 8, wherein said separating means is centrifugal; and said supplying means comprises a container for each of separated components; and conduit means for connecting said mixing valve with said containers.

Claim 13

A system according to Claim 7, wherein said electrostatic field determining means comprises an electrostatic voltmeter; means for supporting said voltmeter from said nozzle; an electrode for receiving the static potential in said tank; and electrode support means for holding said electrode an extended distance beyond the discharge end of said nozzle.

Claim 14

A system according to Claim 10, further comprising a sump for collecting run-off fluid from said cleaining; means for separating said run-off fluid into said two components; and means for supplying said separated components to said mixing valve.

Claim 15

A system according to Claim 11, wherein said separating means is centrifugal; and said supplying means comprises a container for each of said separated components; and conduit means for connecting said mixing valve with said containers.

Claim 16

In mammoth tanker tank-cleaning, a system for preVenting electrostatic charge build-up, comprising in combination a jet nozzle for forming a high-velocity fluid jet to be directed against the walls of said tank; a swivel attached to said nozzle to permit rotation thereof, with motor means for causing said rotation; a pump for forcing a cleaning fluid through said nozzle; said cleaning fluid being comprised of two components; one of said components being clean sea water which tends to produce a negative electrostatic charge; the other of said components being a mixture of oil and sea water which tends to produce a positive electrostatic charge; a mixing valve in series with said pump; a sump for collecting run-off fluid from said tank walls; a pair of containers to act as reservoirs for said components; a centrifugal separator having an inlet and a pair of outlets; means for connecting said inlet to said pump; means for connecting said outlets to said pair of containers; conduit means for connecting said separated components to said mixing valve; an electrostatic voltmeter associated with said jet nozzle; said voltmeter having an electrode for receiving the electrostatic potential in said tank; an electrode support member connected to said voltmeter and extending a predetermined distance beyond the discharge end of said nozzle; and control means for actuating said mixing valve in response to said electrostatic potential in a direction to reduce said potential toward zero.

Claim 17

In mammoth tanker tank-cleaning, a system for preVenting electrostatic charge build-up, comprising in combination a jet nozzle for forming a high-velocity fluid jet to be directed against the walls of said tank; a swivel attached to said nozzle to permit rotation thereof, with motor means for causing said rotation; a pump for forcing a cleaning fluid through said nozzle; said cleaning fluid being comprised of two components; one of said components being clean sea water which tends to produce a negative electrostatic charge; the other of said components being a mixture of oil and sea water which tends to produce a positive electrostatic charge; a mixing valve in series with said pump; a sump for collecting run-off fluid from said tank walls; a pair of containers to act as reservoirs for said components; a centrifugal separator having an inlet and a pair of outlets; means for connecting said inlet to said pump; means for connecting said outlets to said pair of containers; conduit means for connecting said separated components to said mixing valve; an electrostatic voltmeter associated with said jet nozzle; said voltmeter having an electrode for receiving the electrostatic potential in said tank; an electrode support member connected to said voltmeter and extending a predetermined distance beyond the discharge end of said nozzle; and control means for actuating said mixing valve in response to said electrostatic potential in a direction to reduce said potential toward zero.