Additional Information and Specification for Field Machine

The Field Machine is supplied with the following items:

Unless fitted with extensive options the Field Machine is housed in a robust fully screened water resistant IP 68 enclosure with an internally screened mains supply. The instrument has one double-sided circuit board for improved reliability with a minimum of wire links. Both the mains input mains earth and the RS232 / COM link are all electrically isolated to prevent troublesome earth loops. Every Field Machine has an internal Potentiostat; Zero Resistance Ammeter; Frequency Response Analyser and a Galvanostat.

The Field Machine is supplied with the standard programs shown below.  Optional software packages available for this instrument to increase performance are included under options. ACMs version 4 software will operate in all Microsoft Windows operating systems excluding Windows 3.1. 

Sequencer 

The Sequencer is the host program for all the other Version 4 software techniques. It enables series of tests to be performed in a logical sequence. It has a few features of its own including:-

Core Running

The Core Running program actually controls the instrument using the test sequence pre set via the Sequencer. Individual channels can be switched on or off in the Core Running. Real time data for each channel can be observed using typical Windows features such as Full Screen Cascade and Tile. 

Long Term

Tests that obtain and present data from an electrochemical cell or probe with respect to time including Linear Polarisation Resistance; Potentiostatic; Galvanic and Potential monitoring.

Measurements.
Data is presented in real time for instant visual analysis. Typically this technique is used to monitor the corrosion rate in relation to time by using a series of Linear Polarisation Resistance tests. For multiple channel instruments individual windows simultaneously present the data from each respective channel. These techniques represent the basic tools of long term corrosion testing. 

Linear polarisation tests can be controlled in a variety of ways. The two main types are Step and Sweep. Step polarisation’s can be either of the square wave variety or a modified square wave where the cell is left isolated between Anodic and Cathodic polarisations. Sweep options include sweep from rest potential to start potential and initial delays at start potential. 

Cyclic Sweeps

This test is presented on V/ I or V/ Log I graphs typically referred to as Evans Diagrams. Other terms frequently used are Cyclic Voltammetery Potentiodynamic Sweeps and Polarography. A custom sweep facility enables complex Voltage/ Time graphs to be constructed which are then used to polarise the cell. A range of typical tools are available to analyse the data including positioning and measurement of Tafel Slopes and Linear Polarisation Resistance. The corrosion rate may be measured using either the Stearn and Geary or the Current Intercept method. The technique is often used as a traditional way to detect resistance to pitting. To facilitate this a current limit may be used.

C&V Noise

Electrochemical Current and Voltage Noise and Potentiostatic measurements at a rate of 50 or 60 per second whilst rejecting mains interference. Typical measurement accuracy is from a few pA upwards. 

AC Impedance

AC Impedance uses a scan of test frequencies normally from a high to a low frequency to analyse resistive and capacitive characteristics of a corrosion cell. Data is presented in either Nyquist Bode Phase or Bode Impedance formats. Curve fitting software is inclusive to calculate the Solution Resistance Double Layer Capacitance and the Polarisation Resistance. The technique is frequently used in systems with a significant solution resistance or as a method to analyse the performance of a coating. For very high impedance cells greater than 10 MOhms the technique is normally used in conjunction with the optional Paint Buffer. 

Analysis

Screen shots:

ACM instruments supplies analysis software with its products. This offers the user a number of standard tools which are typically used by electrochemists and corrosion scientists. However for user specific analysis we recommend the user to transfer data to a typical commercial package such as Excel. Version 4 analysis software offers the following features:-

Data Management Tools:-

- Browsing data files as thumb nail graphs.
- Selecting data from multiple files into data banks for comparison.
- Exporting individual or batched data files to text or ASCII format suitable for spread sheets.
- Exporting graphs as bitmaps and metafiles for including in reports.
- Storing data in a HTML format suitable for viewing with a web browser or uploading to a web page.

Common Data Manipulation Tools:-

- Cut and paste ability enables graphs to be inserted into text documents with ease.
- Re-definable axis where an axis type and units can be set.
- Editing of data points and joining any gaps created.
- Zero plot enabling data vs. time graphs with different start times to be referenced to zero on the time axis.
- Inclusion of labels to highlight specific points / areas of the graph.
- Printing the graph to include any labels and rulers displayed.
- Zooming where the graph can be rescaled manually automatically or by using the mouse.
- Cursors which can be moved along the data line giving the X and Y co-ordinates as well as data specific information such as average trend and frequency.
- Smoothing of data by averaging adjacent points can be performed on the data either between cursors the selected data bank or all of the displayed data.
- Saving data enables modified graphical data to be stored for later retrieval.
- Corrosion rate calculation in mm or mils per year.

Data Specific Features:-

- Circle fit for Nyquist graphs.
- Isotropic Scaling of Nyquist graphs.
- Tafel rulers for calculation of bA bC and intercepts on V vs LogI graphs.
- Least squares fit and manual line fitting for the calculation of the Linear Polarisation Resistance of a Voltage vs Current graph.
- Fast Fourier Transform graphs created from Current and Voltage data.
- Point to Point graphs created from Current and Voltage data.
- Graphs area calculated from the base line on Current and Voltage graphs.
- Peak counter on Current and Voltage data.
- Load test at cursor on long term LPR step and sweep graphs. This gives the ability to load the sweep or step data relating to the data point at the cursor.
- Ability to analyse data files containing hundreds of thousands of points.

Manual Instrument Control

The Field machine is supplied with Manual Instrument Control. This is a stand alone single page program which tries to recreate the nostalgia of the Manual Potentiostat Sweep Generator and twin channel chart recorder of yesteryear. Rate of movement of the mouse is directly proportional to the rate of change of cell potential. Such tactile feel of an electrochemical cell is typically missing with modern automated systems. It is recommended as an educational or investigative tool. Data is shown in graphical form in real time and stored in an ASCII format for analysis with a typical commercial package such as Excel.

Specifications

	Case	47 * 36 * 14 cm
	Power Supply	110 / 230 VAC 50/60Hz or a 12V source.
	Weight	9Kg

Potentiostat

	Compliance Voltage	+/- 12Volts
	Sweep	+/- 3Volt
	Sweep Resolution	0.025mV Maximum
	Current Output	500mA
	Reference Electrode Input Impedance	Approximately 1*1012 Ohms
	Frequency Response	30 Khz with a 1 to 100KOhm load
	Potential Measurement	21 Bit A/D
	Maximum Potential Resolution	1µV
	Potentiodynamic Sweep Rate	Maximum 20mV / second

Zero Resistance Ammeter

	Current Range	10pA to 500mA
	Current Ranges	Eight ranges
	Counter Resistors	Eight 1 10 100 1K 10K 100K 1M 10M Ohms
	Input Offset Voltage	10µV

Galvanostat

	Current Output	+/- 10pA to 500mA
	Maximum Potential Resolution	1µV

Frequency Response Analyser

	Frequency Range	10µHz to 30KHz
	Amplitude	1 to 232mV
	Impedance Error	< 1% for 1 10 100 1K 10K and 100K Loads
	Averaging	Variable % averaging
	Sample Rate	1 MHz
	ADC	12 Bit
	DAC	12 Bit