Manganese Dioxide Electrodes
Manganese dioxide reference electrodes have been used for monitoring steel potentials in reinforced concrete for 25 years Our RB15 manganese dioxide reference electrode is a long life reference electrode suitable for embedment in concrete to measure the electrical potential of the steel reinforcement. The RB15 is a true half-cell using manganese oxides in a stainless steel housing with an alkaline, chloride free mortar. The pH of the mortar corresponds to that of concrete so errors due to diffusion of ions through the porous plug are eliminated. After manufacturing the electrodes are calibrated under laboratory conditions against a saturated calomel reference electrode and a calibration certificate is issued with each batch of electrodes.
The electrodes are made to order so any reasonable cable specification can be met. The standard stock cables are a 2.5mm2 copper stranded cable using blue XLPE/XLPE sheathing. Alternatively the electrodes can be supplied without cable for cable attachment on site. Click here for the method statement for cable attachment.
Silver/Silver Chloride/0.5M KCL Electrodes
A range of silver/silver chloride/0.5M KCL reference electrodes are supplied for atmospherically exposed reinforced concrete. They are not suitable for submerged seawater or splash zones where our RB15 manganese dioxide units are more suitable. These reference electrodes are true electrodes in the thermodynamic sense and are designed to be used for monitoring steel potentials in reinforced concrete, steel framed buildings and buried steel. The reference potentials for these electrodes are established in accordance with the Nernst equation and as such are affected only by chloride ion concentration and temperature at the element surface.
One of the common problems with silver/silver chloride electrodes used in reinforced concrete is that they have a tendency to dry out due to seasonal changes in the climate. This phenomenon has been eliminated by using a moisture retaining chloride mortar which ensures that the electrode continues to function in abnormally dry conditions which is a unique characteristic found only in these electrodes.
There are currently three standard reference electrodes in the range. They are the LD10, LD15, LD25. The difference between the units is the size, the amount of silver and the area of the measurement interfaces. The most popular units are the LD15 and LD25 which are used for reinforced concrete. The LD10 units are often used for steel framed buildings where there is limited access available.
After manufacturing the electrodes are calibrated against a saturated calomel standard reference electrode in laboratory conditions and a calibration certificate is issued with each batch of electrodes. Prior to installation it is recommended that a functional check is undertaken by the installer to check that the electrode potentials are stable. Due to the sensitivity of the measurements it is not possible to repeat the calibration procedure on site with any degree of accuracy. It is essential that the installation procedures for the electrodes are adhered to unless otherwise agreed.
The electrodes are made to order so any reasonable cable specification can be met. The standard stock cables are a 2.5mm2 copper stranded cable using blue XLPE/PVC or XLPE/XLPE sheathing or a 1.5mm2 blue high performance cable. If there is any delay in manufacturing it is usually due to an unusual cable specification requirement. Alternatively the electrodes can be supplied without cable but with a spade connector on the silver wire for cable attachment and resin encapsulation on site. Click here to see the method statement for cable attachment.Silver Chloride Electrodes Product Page
Combined Potential & Current Measurements
This can be an RB15 or LD15 reference electrode with a mixed metal oxide (MMO) coated titanium sleeve. This enables the measurement of steel potential and current flow to an operating CP system or the MMO titanium unit can be used as a pseudo reference electrode if the RB15 or LD15 unit fails in the future.
These are not thermodynamically true reference electrodes and are commonly known as pseudo electrodes. They are not suitable for measuring either absolute potentials or relative potentials over a period of weeks or months. They are designed for the rugged construction environment and have a measurement area of 4000mm2 which ensures good contact with concrete.
The reference potential is primarily due to the oxygen reduction reaction and is determined by the amount of oxygen reaching the surface. Also the potential value is affected by the hydroxyl ion concentration in the vicinity of the electrode.
Silver/Silver chloride reference electrodes have been used for many years to provide reliable potential monitoring of steel in contact with seawater.
They are often used to monitor catholic protection systems for salt-seawater pipelines and steel structures such as jetties and sheet piling. In seawater the cells assume a potential which is dependent on the chloride ion concentration.
The company supplies a range of electrodes for both permanent and portable use.
The permanent cells are provided in three body sizes.
- LD10W 80mm long x 10mm diameter
- LD15W 75mm long x 15mm diameter
- LD25W 75mm long x 24 mm diameter
The portable unit LD200W is a much larger weighted unit which can be lowered into the seawater to measure steel potentials during monitoring visits.
This electrode consists of a titanium metal rod with a mixed metal oxide coating. It is pseudo reference electrode and is suitable for short term potential measurements such as in the monitoring of cathodic protection systems.
This is a high purity zinc rod which is often used as a reference in marine environments and occasionally in concrete. They are pseudo reference electrodes which can be used for short term potential measurements.