Underground storage tank monitoring system and method

• US 6,374,187 B1
• Filed: 03/19/1999
• Issued: 04/16/2002
• Est. Priority Date: 03/19/1999
• Status: Expired due to Fees

• Current Assignee: Simmons Sirvey Corporation (Dover Corporation)
• Original Assignee: Simmons Sirvey Corporation (Dover Corporation)
• Inventors: Knight, John D., Grempler, Charles
• Primary Examiner(s): CECIL, TERRY K
• Assistant Examiner(s): Le, John
• Application Number:
  US09/272,790
• Time in Patent Office: 1,124 Days
• Field of Search: 738/612--86, 702/51, 702/55, 340/603, 340/612, 340/618, 340/621
• US Class Current: 702/51
• CPC Class Codes: G01F 23/284 Electromagnetic waves
• CPC Class Codes: G01F 23/802 Particular electronic circuits for digital processing equipment
• CPC Class Codes: G01S 13/0209 Systems with very large relative bandwidth, i.e. larger than 10 %, e.g. baseband, pulse, carrier-free, ultrawideband
• CPC Class Codes: G01S 13/88 Radar or analogous systems specially adapted for specific applications electromagnetic prospecting or detecting of objects, e.g. near-field detection, G01V3/00
• CPC Class Codes: G01S 7/02 of systems according to group G01S13/00

Abstract

An underground storage tank monitoring system and method uses special micropower impulse radar probes, with one such probe being inserted into each storage tank. The micropower impulse radar probes use flexible waveguides which extend downward to the tank bottom such that micropower radar impulses travel to and from the liquid surface via a wave guide, with the lapse between emission and reception of the impulse indicating a distance from the probe, and thus a liquid level. Each micropower impulse radar probe is connected to a dedicated spread spectrum transmitter which collects level and status information from the probe, encodes and transmits it to a matching spread spectrum receiver nearby. The receiver converts the coded signals into electrical signals and forwards them to a processor, a modem and a back-up battery are located. The processor stores the liquid level information for later transmission, along with liquid dispensed and liquid replaced information, to a central monitoring site via the modem.

Claims

1. A liquid storage tank monitoring system which monitors liquid level in a plurality of storage tanks, comprising:

a) a plurality of micropower impulse radar probes, each of which is installed in a respective one of said tanks, each of said probes being operative to transmit micropower radar impulses toward the surface of liquid contained in their respective tank, to receive reflected micropower radar impulses returning from said liquid surface, and to calculate a liquid level information from the time lapse between transmission of the impulses and reception of the reflected impulses;

b) a like plurality of spread spectrum transmitters and antennas, with each such transmitter being coupled to a respective one of said probes, each said transmitter receiving said liquid level information from the probe coupled thereto and being operative to encode and transmit said liquid level information;

c) at least one spread spectrum receiver positioned in a location in which it can reliably receive and decode liquid level information transmitted by said spread spectrum transmitters and antennas; and

d) a respective processor connected to each said receiver to receive and store said liquid level information.

2. A liquid storage tank monitoring system as in claim 1, wherein at least some of said micropower impulse radar probes are inserted into their respective tanks via a fill riser.

3. A liquid storage tank monitoring system as in claim 2, and further comprising a probe installation system for each of said micropower impulse radar probes which are inserted via the fill riser, each said installation system including:

a) a riser adapter with a cable routing opening extending through a side wall thereof;

b) an L shaped cable guide attached to and extending downward through said fill riser and into said tank;

c) a probe hinge bracket positioned on the cable guide, said hinge bracket securing said micropower impulse radar probe such that it is pivotable with respect to said cable guide between a substantially vertical position required for insertion through the fill riser and a substantially horizontal, operative position; and

d) a drop tube with an external groove extending substantially along its length, said drop tube being insertable within said fill riser with said groove accommodating said cable guide, said drop tube, upon insertion, engaging said hinge bracket and pivoting said hinge bracket and said micropower impulse radar probe from said substantially vertical position to said substantially horizontal position.

4. A liquid storage tank monitoring system as in claim 1, wherein there are a plurality of service stations, each with a plurality of storage tanks with each service station including one of said spread spectrum receivers which receives signals from transmitters located at that service station and one of said processors, said system further comprising:

a) a central monitoring site which is connectable with each of said service station processors, said processors periodically sending liquid level information to said central monitoring site where data is compiled to enable the central monitoring site to do leak analysis on each tank.

5. A liquid storage tank monitoring system as in claim 4, wherein each of said processors includes a data entry device for inputting liquid dispensed and liquid replaced information for each tank in addition to said liquid level information, each said processor also forwarding said liquid dispensed and liquid replaced information to said central monitoring site.

6. An underground fuel storage tank monitoring system which monitors fuel levels, detects leaks and other conditions in a plurality of storage tanks located at a plurality of different fuel service stations from a central location, comprising:

a) a plurality of micropower impulse radar probes, each of which is installed in a respective one of said tanks, each of said probes being operative to transmit micropower radar impulses toward the surface of fuel contained in their respective tank, to receive reflected micropower radar impulses returning from said fuel surface, and to calculate fuel level information from the time lapse between transmission of the impulses and reception of the reflected impulses;

b) a like plurality of spread spectrum transmitters and antennas, with each such transmitter being coupled to a respective one of said micropower impulse radar probes, each said transmitter receiving said fuel level information from the probe coupled thereto and being operative to encode and transmit said fuel level information;

c) a plurality of one spread spectrum receivers, each said receiver being positioned at a respective one of said service stations in a location in which it can reliably receive and decode fuel level information transmitted by said spread spectrum transmitters and antennas located at that service station;

d) a plurality of processors, each said processor being positioned at a respective one of said service stations and being connected to each said receiver to receive and store said fuel level information for each tank at that service station; and

e) a central monitoring site which is connectable with each of said service station processors, said processors periodically sending fuel level information to said central monitoring site where data is compiled to enable the central monitoring site to do leak analysis on each tank.

7. An underground fuel storage tank monitoring system as in claim 6, wherein at least some of said micropower impulse radar probes are inserted into their respective tanks via a fill riser.

8. An underground fuel storage tank monitoring system as in claim 7, and further comprising a probe installation system for each of said micropower impulse radar probes which are inserted via the fill riser, each said installation system including:

a) a riser adapter with a cable routing opening extending through a side wall thereof;

b) an L shaped cable guide attached to and extending downward through said fill riser and into said tank;

c) a probe hinge bracket positioned on the cable guide, said hinge bracket securing said probe such that it is pivotable with respect to said cable guide between a substantially vertical position required for insertion through the fill riser and a substantially horizontal, operative position; and

d) a drop tube with an external groove extending substantially along its length, said drop tube being insertable within said fill riser with said groove accommodating said cable guide, said drop tube, upon insertion, engaging said hinge bracket and pivoting said hinge bracket and said probe from said substantially vertical position to said substantially horizontal position.

9. An underground fuel storage tank monitoring system as in claim 6, wherein each of said processors includes a data entry device for inputting fuel dispensed and fuel replaced information for each tank in addition to said fuel level information, each said processor also forwarding said fuel dispensed and fuel replaced information to said central monitoring site.

10. A method of monitoring fuel levels, detecting leaks and other conditions in a plurality of storage tanks located at a plurality of different fuel service stations from a central location, comprising:

a) installing a respective fuel level micropower impulse radar probe in each of said tanks, each of said probes being operative to transmit micropower radar impulses toward the surface of fuel contained in their respective tank, to receive reflected micropower radar impulses returning from said fuel surface, and to calculate fuel level information from the time lapse between transmission of the impulses and reception of the reflected impulses;

b) positioning a like plurality of spread spectrum transmitters and antennas, with each such transmitter being coupled to a respective one of said probes, each said transmitter receiving said fuel level information from the micropower impulse radar probe coupled thereto and being operative to encode and transmit said fuel level information;

c) positioning a respective spread spectrum receiver at each one of said service stations in a location in which it can reliably receive and decode fuel level information transmitted by said spread spectrum transmitters and antennas located at that service station;

d) positioning a respective processor at each one of said service stations and connecting each processor to the receiver at that station to receive and store said fuel level information for each tank at that service station; and

e) transmitting fuel level information from each said processor to a central monitoring site where data is compiled to enable the central monitoring site to do leak analysis on each tank.

11. A monitoring method as in claim 10, wherein said probe installation step includes the step of installing at least some of said micropower impulse radar probes into their respective tanks via a fill riser.

12. A monitoring method as in claim 11, said fill riser probe installation steps comprising the steps of:

a) removing any existing drop tubes from the fill riser;

b) installing a riser adapter with a cable routing opening extending through a side wall thereof on the fill riser;

c) attaching a micropower impulse radar probe with an attached wave guide to a probe hinge bracket;

d) positioning said probe hinge bracket on an L shaped cable guide, said hinge bracket securing said micropower impulse radar probe such that it is pivotable with respect to said cable guide between a substantially vertical position required for insertion through the fill riser and a substantially horizontal, operative position;

e) inserting said cable guide, hinge bracket and micropower impulse radar probe through said fill riser such that the probe and hinge bracket are positioned in said tank;

f) extending an upper angled leg of said cable bracket through said cable routing opening; and

g) inserting a drop tube with an external groove extending substantially along its length into said fill riser with said groove accommodating said cable guide, said drop tube, upon insertion, engaging said hinge bracket and pivoting said hinge bracket and said micropower impulse radar probe from said substantially vertical position to said substantially horizontal position.

13. A monitoring method as in claim 10, wherein each of said processors includes a data entry device, said method further comprising the steps of:

a) inputting fuel dispensed and fuel replaced information for each tank at that service station into each processor in addition to said fuel level information; and

b) periodically forwarding said fuel dispensed and fuel replaced information to said central monitoring site in addition to said fuel level information.

14. An installation system for installing a liquid level sensing micropower impulse radar probe into a liquid storage tank via a fill riser, comprising:

a) a riser adapter with a cable routing opening extending through a side wall thereof;

b) an L shaped cable guide with an upper, angled leg being insertable in said cable routing opening;

c) a probe hinge bracket adapted to mount the micropower impulse radar probe onto said cable guide such that a portion of said hinge bracket and the probe are pivotable with respect to said cable guide between a substantially vertical position required for insertion through the fill riser and a substantially horizontal, operative position within said tank; and

d) a drop tube with an external groove extending substantially along its length, said external groove being sized and positioned to accommodate said cable guide as said drop tube is inserted into the fill riser.