Reference cell

Details Reference cell Reference cell

1992-04-27

2001-02-13

Tung, T. (Department: 1743)

Chemistry: electrical and wave energy

Apparatus

Electrolytic

C204S196010, C204S196060, C204S196330, C204S196360, C205S724000, C205S727000

Reexamination Certificate

active

06187161

ABSTRACT:

This invention relates generally as indicated to a reference cell and more particularly to a reference cell-test station combination, prepackaged, assembled, and tested, for installation as a unit.
BACKGROUND OF THE INVENTION
Cathodic protection systems may be monitored by permanent or portable reference cells. Portable reference cells may provide readings of questionable reliability since the results are dependent on a variety of factors such as cell placement and surface soil conditions. It requires an experienced and skilled technician to obtain reasonably reliable readings.
A permanent reference cell is more reliable but requires installation in the ground or electrolyte spaced from the buried or submerged structure. The cell is connected to a test station which must be accessible, i.e. normally above ground or not submerged. The test station is also electrically connected to the structure enabling the potential measurement to be taken conveniently at the test station.
A permanent reference cell must have a long design life and be relatively easy to install. Moreover, the installation procedure should itself avoid damage to the cell or test station. The test station should also be simple and easy to use. Over a long design life, the test station may itself be subject to corrosion, or more likely vandalism if caps can be removed or doors opened to provide access to the particular wiring connections. This is particularly true if the wiring connections provide movable or removable parts such as binding posts or even banana jacks.
Conventionally, an installing contractor orders a reference cell, a test station or terminal box, and sufficient wire to connect the cell to the test station and the test station to the buried structure or structures. The wiring connections are done in the field at what is usually a major construction site involving excavation, excavation machinery, backfills, backfill machinery and sometimes the removal and installation or replacement of pavement. This is all usually accomplished in an environment of mud or dirt. Before the system is backfilled, the system is tested. Complete aggravation results when the system is tested after installation and backfill and fails to work properly. Failure most often occurs at the electrical connections which are made in the field and subject to the visits of a construction site. Examples of cells commercially available are a variety of cells sold under the trademark PERMACELL® by Harco Corporation of Medina, Ohio. These include underground copper-copper sulphate, or silver-silver chloride cells, and silver-silver chloride cells for salt water applications. A variety of test stations are also available usually requiring removable caps, doors, etc., and binding post or banana jack wiring connections.
SUMMARY OF THE INVENTION
The present invention integrates an improved cell and the test station in a unitary package which includes internally encapsulated wiring connections at both the cell and test station. The cell and test station are tethered together by a flexible bungee tube which can be coiled and which can elongate or contract. The flexible tube integrates the two units at each end yet provides a variable length and wide lateral flexibility. The tube also provides a convenient means to encapsulate the connections at both the cell and test station.
The cell comprises a unique canister or core formed by a double junction ceramic capsule. A pure copper coil element is positioned in the capsule in a super saturated solution of copper sulphate, for example. The capsule is sealed and the coil or element is electrically connected to a lead extending through the tube, and the end of the tube is encapsulated sealing the connection. The capsule is joined to one end of the flexible tube and the entire end is embedded in a stabilized hygroscopic thixotropic gel which contains additional salt crystals. The entire cell end of the tube is contained in a durable geotextile microporous filter bag, which is in turn secured to the lower end of the tube. The cell end is sealed in a plastic bag until ready for use.
The test station comprises a section of rigid plastic tube with a slightly domed cap. The length of the rigid plastic tube may vary depending on whether the test station is flush or post mounted. Brass rivets are recessed in the top of the dome and connected to appropriate wiring inside the dome. The interior of the test station is then encapsulated fully sealing the wiring connections.
The brass rivets or buttons are placed on the dome so that a reading may quickly be taken by a two-prong test probe. If more than one buried or submerged structure is being monitored, the spacing is such that structure-to-structure potentials cannot be read by mistake.
The slightly domed top surface of the test station enables it to be mounted flush with pavement. The material is a tough ultraviolet resistant plastic which can withstand vehicle traffic and wear. The dome configuration elevates the contacts above ponding which may occur on pavement after or during inclement weather. This reduces the probability of corrosion of the contacts.
Optionally the test station and cell may be interconnected by a small plastic tube so that the cell may be replenished, and so that test measurement may be made through the tube, acting as a salt bridge. Both the interconnecting lead and the small plastic tube, if used, may be slightly coiled in the flexible tube so that even maximum elongation of the tethering flexible tube will put no tension on the lead wire or its connections. The flexible tube may be corrugated, such corrugations acting to protect the lead inside, while providing greater axial elongation.
It is a principal object of the present invention to provide a totally integrated cell and test station system which is complete with a test station, wiring, and a permanent reference cell which has a long design life. More importantly, the cell-test station combination can readily be factory fabricated and tested, coiled for shipment, and readily installed at the construction site without requiring field electrical connections, other than those connecting the test station to the structure, or other field fabrications or manipulations which can adversely affect the performance and life of the installation.
To the accomplishment of the foregoing and related ends the invention, then, comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawings setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principles of the invention may be employed.


REFERENCES:
patent: 2639265 (1953-05-01), Simcox
patent: 2810690 (1957-10-01), Campise et al.
patent: 3037926 (1962-06-01), Ambler
patent: 3192144 (1965-06-01), Heuze
patent: 3725669 (1973-04-01), Tatum
patent: 3787307 (1974-01-01), Schwab et al.
patent: 3954591 (1976-05-01), Conkling
patent: 4056446 (1977-11-01), Vennett
patent: 4080565 (1978-03-01), Polak et al.
patent: 4133732 (1979-01-01), Boeke
patent: 4166021 (1979-08-01), Ross et al.
patent: 4758324 (1988-07-01), Winneti et al.

Affiliated with

Also associated with

Rating

Reference cell does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Reference cell, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Reference cell will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2603977