DE3347046C2 - Measuring probe for measuring the electrical potential above the bottom of liquid containers with cathodic corrosion protection - Google Patents

Abstract

The invention relates to a measuring probe for measuring the electrical potential in liquid containers with cathodic corrosion protection with an electrode rod which is arranged in a porous-walled holder with an electrolytic liquid. The invention consists in that the electrode holder 3 is housed in a cylindrical measuring capsule 5, which has lateral openings 6 a short distance above the base 5b and is in turn arranged axially movable against the action of a spring 8 in a probe casing 7 open at the bottom. The measuring capsule 5 is positively connected to the pull wire 9 of a Bowden cable 10, which penetrates the probe jacket 7 and the measuring capsule 5 and is connected to the electrode rod 1.

Description

characterized by the following features:

d) the electrode holder (3) with electrode rod (1) and electrolytic liquid (4) is housed in a cylindrical measuring capsule (5) with a removable cover (5a) , which at a small distance above the base (5b) has at least one lateral opening ( 6) has;

e) the measuring capsule (5) is movable in a probe jacket (7) against the action of a spring (8) arranged on the outer wall of the measuring capsule (5) at least in the region of the opening or openings (6) of the measuring capsule lies tightly closed;

f) the measuring capsule (5) is connected to the pull wire (9) on the probe jacket! (7) supportive Bowden cable (10) connected to the probe jacket (7) and the measuring capsule (5) penetrates and is connected to the electrode rod (1) directly or via an intermediate member and forms at least part of a power line connectable to a voltmeter;

g) the probe jacket (7) has at least one opening in the lower area, which can be opened by actuation of the Bowden cable (10) via at least one opening (6) at the lower end of the measuring capsule (5) is movable.

2. Measuring probe according to claim 1, characterized by the following features:

a) the probe casing (7) is higher than the measuring capsule (5), a cavity being present between the cover (5a) of the measuring capsule and the end wall (7a ^ of the probe casing;

b) the probe casing (7) is open at the bottom, with the measuring capsule (5) partially protruding axially from the probe casing (7) can be pushed out;

c) on the inner wall of the probe jacket (7) is a the level of the upper edge of the measuring capsule (5) axial movement of the measuring capsule (5) upwardly restricting stop ^ typrovided;

d) a compression spring (8) is arranged in the probe jacket (7) above the measuring capsule (5), which at the upper end position of the measuring capsule (5)

is under tension;

e) the front wall (7a) of the probe jacket and the removable cover (5a) of the measuring capsule each have a central bore through which the pull wire (9) of a Bowden cable (10) supported on the front wall (7a) of the probe jacket is guided;

f) the pull wire (9) of the Bowden cable (10) engages the upper end of the electrode rod (1) and thereby forms at least part of a power line that can be connected to a voltmeter, with the measuring capsule on the pull wire (9) below the cover (5a) Bowden cable (10) an abutment (11) is arranged for the purpose of frictional connection with the measuring capsule (5);

g of the Bowden cable (ίθ) is o ^f a central bore in the end wall (7a) of the probe sheath surrounding threaded connection piece (13) sealingly screwed) by means of a screw cap (12)

3. Measuring probe according to claims 1 and 2, characterized in that the probe jacket (7) is divided transversely at the level of the stop (7b) and that both parts are detachably connected to one another by a coaxial screw connection (7c).

4. Measuring probe according to Claims 1 to 3, characterized in that the stop (7b) limiting the axial mobility of the measuring capsule (5) in the probe casing (7) is formed by an inside wall thickening of the probe casing (7) above the measuring capsule (5) is.

5. Measuring probe according to claims 1 to 4, characterized in that the probe jacket (7) has an annular groove-like recess in its inner surface immediately above the lower edge, in which a sealing ring (7d) is arranged.

6. Measuring probe according to claim 1, characterized in that the measuring capsule (5) in the probe jacket (7) rotatably arranged between two stops against a spring by means of a Bowden cable net, wherein the pull wire of the Bowden cable is at least part of a power line between the Forms electrode rod and a voltmeter and the probe jacket in the lower area at least has a lateral opening which, in a rotational end position of the measuring capsule, has at least one opening releases in the measuring capsule wall and in the other rotary end position all openings in the measuring capsule wall tightly closed.

The invention relates to a measuring probe for measuring the electrical potential above the bottom of liquid containers with cathodic corrosion protection with sacrificial anodes arranged on the tank bottom and an electrolyte liquid that is heavier than the contents of the container and surrounds the sacrificial anodes.

The cathodic corrosion protection for z. B. underground heating oil tanks or oil pipelines made of steel is in terms of its protective effect by measuring the electrical potential on the protected Object verifiable. The voltage difference between the one forming the cathode is protected Object and a reference electrode.

For this purpose, copper reference anodes have proven themselves in practice, with an electrode rod in one with A ceramic or clay electrode holder filled with a saturated copper sulphate solution is arranged

The upper end of the copper rod protrudes through a stopper that closes the electrode holder and is connected to a lead wire to the voltmeter. The reference electrode applied to the humid or naturally humid environment (soil) of the protected object

This school monitoring through potential measurement is very practical as the measurements can be carried out quickly and easily.

In the meantime, free-standing containers, in particular heating oil storage tanks, have been given cathodic corrosion protection enforced in such a way that in the container above the bottom one or more, of one the container bottom covering electrolytic liquid surrounding »sacrificial anodes« are arranged. To this In this way, a galvanic element is formed, the effect of which ends when the sacrificial anodes are consumed With this type of cathodic corrosion protection, too, it is necessary that the effectiveness of the protective device is monitored. However, the type of potential measurement method described above cannot be used for this purpose. The electrode holder would be in its porous wall structure when immersing the tank contents, z. B. Pick up fuel oil, electrically insulating oil, so that an exact measurement of the electrical potential in the electrolyte liquid below the heating oil is no longer possible

There are no other control options without clarifying and cleaning the container to be checked known.

The invention is therefore based on the object of monitoring technology by measuring the electrical To perfect the potential so that it can also be used with free-standing containers, e.g. B. Heating oil storage tanks for each The filling level of the container can be carried out quickly and easily.

To solve this problem, the invention is based on the use of a so-called reference electrode, an electrode rod which can be connected to a voltmeter by a power line in one Electrode quiver made of ceramic or clay is arranged, which is filled with an electrolytic liquid.

The object set is achieved according to the invention by a measuring probe with the features according to claim 1.

A preferred embodiment of a measuring probe according to the invention is based on the characteristics of the claims 2 and 3.

An alternative embodiment of the measuring probe is disclosed in the characterizing part of claims 4 to 6.

The electrode rod is expediently made of copper, with the one surrounding it in the electrode holder electrolytic liquid is a saturated solution of copper sulfate.

The electrode rod can, however, also consist of another container opposite the wall of the container to be checked nobler metal, e.g. B. cadmium, with the liquid surrounding it in the electrode holder a is saturated cadmium sulfate solution.

The invention is explained in more detail below with reference to a drawing showing it as an example. The drawing shows an axial section through a measuring probe according to the invention. The most important Components of the measuring probe are an electrode rod 1 made of a metal to be controlled A noble metal container, which can be connected to the positive pole of a voltmeter via a power line is as well as one which receives the electrode rod and is perforated by one of the electrode rod Stopper 2 or a cap closable electrode holder 3 made of ceramic and one the electrode rod 1 in the electrode holder 3 surrounding electrolytic liquid 4, which consists of a saturated solution ίο consists of a salt of the electrode rod material

The electrode holder 3 with the electrode rod 1 and electrolytic liquid 4 is accommodated in a cylindrical measuring capsule 5 with a removable cover 5a, which has several openings 6 a short distance above the base 5b.

The measuring capsule 5 is arranged axially movable against the action of a spring 8 in a probe jacket 7, which rests tightly against the outer wall of the measuring capsule 5 at least in the area of the openings 6 of the measuring capsule of the probe jacket 7 supporting Bowden cable 10, which penetrates the end wall 7a of the probe jacket and the cover 5a of the measuring capsule and engages the electrode rod 1. The pull wire 9 of the Bowden cable 10 forms part of a power line that can be connected to a voltmeter.

The probe jacket 7 is higher than the measuring capsule 5, a cavity being present between the cover 5a of the measuring capsule and the end wall 7a of the probe jacket. The probe casing 7 is open at the bottom, and the measuring capsule 5 can be pushed axially out of the probe casing 7. On the inner wall of the probe jacket 7, at the level of the upper edge of the measuring capsule 5, a stop Tb limiting the axial movement of the measuring capsule 5 upward is provided. In the cavity between the cover 5a of the measuring capsule 5 and the end wall 7a of the probe jacket, a spring 8 is arranged, which is under tension in the upper end position of the measuring capsule 5.

The probe jacket 7 is divided transversely at the level of the stop Tb. Both parts are detachably connected to one another by a coaxial screw connection Tc.
On the inner surface of the probe jacket 7, immediately above the lower edge, an annular groove is provided in which a sealing ring Td is arranged.

Below the cover 5a of the measuring capsule is on the pull wire 9 of the Bowden cable 10 for the purpose of frictional connection Connection of the same with the measuring capsule 5, an abutment 11 is arranged. By the spring 8 in the upper part of the Probe jacket 7, the measuring capsule 5 is partially pushed out of the probe jacket so that the openings 6 near the lower end of the measuring capsule are free.

The Bowden cable 10 is through a screw cap 12 on a central hole in the end wall 7a of the The threaded connector 13 surrounding the probe jacket is screwed tightly.

By tightening the pull wire 9 in the Bowden cable 10, the measuring capsule 5 can counteract the action of the spring 8 in the probe jacket 7 are drawn in so that the openings 6 on the measuring capsule 5 are closed. In In this state, the measuring probe can be filled with any size, e.g. B. heating oil in a heating oil tank, lowered are down into the electrolyte liquid above the bottom of the container. After releasing the pull wire 9 in Bowden cable 10 pushes the compression spring 8, the measuring capsule 5 again a little bit out of the probe jacket 7: the

Openings 6 on the measuring capsule 5 are open and an electrically conductive connection between the electrode rod 1 and the electrolytic liquid above the container bottom is established.

After the measurement has ended, the measuring capsule 5 is returned to the probe jacket by actuating the Bowden cable 10 7 pulled in. The measuring probe can now be lifted out of the container again through the product without the electrode holder 3 coming into contact with the product.

The electrode rod is - as in the known devices - preferably made of copper, the him in the electrode holder 3 surrounding electrolytic liquid 4 is a saturated copper sulfate solution. However, it can also be made of another metal that is more noble than the metal of the container to be checked consist, for example of cadmium, with the surrounding the electrode rod in the electrode holder Liquid is a saturated cadmium sulfate solution.

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Claims (1)

Patent claims: 1. Measuring probe for measuring the electrical potential above the bottom of liquid containers with cathodic corrosion protection with sacrificial anodes arranged on the tank bottom and one Electrolyte liquid that is heavier than the product of the container and surrounding the sacrificial anodes, with 10 a) an electrode rod made of a metal that is more noble than the metal of the container wall, which can be connected by a power line to the positive pole of a voltmeter; b) one that receives the electrode rod and penetrates through one of the electrode rods Plug or cap sealable electrode holder with porous bottom and / or porous wall; c) an electrolytic liquid surrounding the electrode rod in the electrode holder;