Which instruments should I use?

Why use electrochemical techniques to monitor corrosion?

Corrosion is the destructive attack of a material by reaction with its environment. Corrosion control is achieved by recognising and understanding corrosion mechanisms. Following the research of the English scientist Michael Faraday it has been understood that most corrosion is electrochemical in nature. Since corrosion is an electrochemical process, it follows that electrochemical techniques and electrochemical instrumentation can be used to study the corrosion process.

Electrochemical techniques are popular because they are fast, accurate and versatile. Much faster than weight loss coupons, accurate even to the lowest corrosion rates and versatile enough to cope with any test in laboratory or field it is easy to see why electrochemical instruments are the bedrock of corrosion research. A number of electrochemical techniques have been developed specifically for corrosion measurement. Among these techniques are Linear Polarization Resistance, Cyclic Polarisation, Potentiostatic testing, Galvanodynamic sweeps, and Critical Pitting Temperature tests. All these tests are very straightforward to employ in a corrosion laboratory or in the field. 

For the newcomer to corrosion we recommend the Corrosion and Protection Centre, [University of Manchester]. Established in 1972 it offers an excellent Masters course in corrosion as well as numerous short course options. One of the world's first dedicated corrosion centres it encourages specialists from different academic disciplines to cross their traditional boundaries and work in relevant areas of corrosion and protection.

Which Instruments should I use?

Below a number of suitable models for corrosion are suggested, but if you're not sure or you can't find what you need, contact us and we will point you in the right direction with our first class service.

For single channel lab instruments you should take a look at our gill ac range. Our standard Gill AC model is our best seller, boasting all the capabilities of its larger brothers and representing very good value for money. The rest of the range meets more specific needs. For low currents we offer our new FemtoAmp, the best performing low current instrument on the market. We also offer models for high currents, faster sweeps, to test welds and much more. Click here to go through to our gill ac pages.

For multiple sequential lab instruments we provide the Gill 8 and the Gill 12, our flagship laboratory models. Offering Two Amps of output and 8 or 12 sequential channels they will take pride of place in any corrosion laboratory. All instruments come with a full compliment of AC and DC software including such different tests as Harmonic Analysis and Galvanodynamic, no need for a long options list like a Mercedes!

The Field Machine is the best instrument in the world for corrosion testing in the field, here at ACM we are very proud of this instrument. Housed in a rugged waterproof case, protecting the electronics and portable PC, this instrument will perform all the corrosion tests, both AC and DC, on multiple channels whilst running under it's own considerable battery power. Once you own a Field Machine you will wonder how you ever managed without one!

The Weld Tester is a very serious piece of equipment. Like many ACM products it is unique. Able to test up to 5 parts of any couple simultaneously with AC and DC tests it allows the response of each segment to be determined. The multi-element cell could be a sectioned weld or a mixed metal system. Up to 12 separate cells can be tested, ideal for checking weld sensitisation in relation to real operational fluids or even mixed metal heat exchangers. The Weld Tester does not just test welds!

Now for some of the other, more specialised, instruments:

The Mini Field Machine is a small instrument housed in a very rugged dive case. Performing all DC tests it is popular for it's light weight and versatility. At a reasonable price it is tough enough for 'fit and forget' applications in the field as well as conventional portable testing. The professional appearance of the Mini Field Machine ensures respect.

The GalvoGill 12 avoids the problems generated by multiplex units when performing long term tests. Twelve Zero Resistance Ammeters (ZRA's) constantly monitor twelve pairs of electrodes to record the current flow with time. There are no switching currents as in a multiplexed system. Each pair may also have a reference electrode which is fully buffered and recorded.

The Pot 16 has 16 potentiostats built in, each at a fixed range i.e. not changed through the software. This allows very long tests of electrodes under potentiostatic control to be performed in complete certainty that the set potential will not be changed. The current flowing is recorded with time. Ideal for testing cathodic disbonding, CP systems, and sensitisation with no multiplexer switching spikes.

The Parallel 30 LPR comprises thirty channels, two or three electrode. Each channel has a dedicated potentiostat and a four range ZRA for the determination of corrosion rate using LPR. The cells can be two or three electrode, when in three electrode mode the software allows for the LPR test to be performed at the rest potential. A very cost effective multichannel corrosion tester.

The Isolated 20 allows for individual pairs of working electrodes, with reference electrode, to be used in a common electrolyte without stray galvanic coupling between the pairs. The galvanic couples are maintained by 20 individual ZRA's, each galvanically isolated from the others unlike the GalvoGill 12 in which each pair is referenced to instrument ground (never mains ground in one of our instruments).

The Bubble Test is software for use with a Gill 12 or any collection of Gill AC's. Designed to test oilfield inhibitors it produces perfect reports with graphs showing percentage inhibition and charts. The philosophy behind this software was simplicity and ease of use, allowing any untrained operator to produce very technical reports on the performance of inhibited systems.

The Critical Pitting Temperature test offers a standard ASTM test with full control of the heating cycle and potentiostatic settings. The ability to perform this test is built into every Gill AC, and may be made operational on request. 

The Speedy 9 was originally built by us for biological research. Each of it's 9 channels has a dedicated pair of 24 bit ADC's to measure current and voltage and 8 decades of count resistors. The result is a device that can measure current and voltage at 60 readings per second for each channel; 1,080 twenty-four bit readings per second. This high speed may be applied during a cyclic sweep, at a fixed potential, or during galvanic measurements.

If you have reached here and still have not decided which instrument you would like perhaps you need one of our Task Master range. These are customised to your exact requirements and, because they usually perform a single specialised test, they often cost less than a fully equipped Gill AC, Gill 8, or Field Machine. Just tell us your requirements and we will quote price and delivery within 24 hours. Finally, all ACM Instruments are now covered by our great new 2 year warranty for your peace of mind.

Recommended Instrumentation

Gill 8

Gill AC

Weld Tester

Field Machine

Mini Field Machine

[   Speedy 9  |   Pot 16  |  GalvoGill 12   |  Parallel LPR 30  |  Isolated 20  |   Pocket Machine ]

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