PosiTector^® 6000

PA2

Instruction Manual Addendum

This addendum to instruction manual v6.0/M is intended to provide support for the SSPC-PA2 feature found in all PosiTector 6000 memory(3) models with serial numbers greater than 600000.

What is SSPC? What is PA2? Overview of the PosiTector's PA2 mode Q&A

How to use the PosiTector 6000's PA2 mode...

Step 1 - Begin a PA2 analysis.

Select the Memory option from the gage menu as shown.	Next, select the PA2 option from the Memory menu

Step 2 - Adjust PA2 parameters as necessary.

Review the 6 parameters. To adjust a parameter, use the (-) and (+) buttons to move the highlighting bar to the appropriate parameter, press the middle button, then adjust that parameter as shown.

The 6 adjustable parameters are...

MIN:  the specified minimum thickness value for the coating system. If only one target thickness is specified, set the MIN to that value. Adjust the displayed value down (-) or up (+). Alternatively, measure a coating with a thickness close to the required value and make final adjustments with the buttons. Press the middle button to save and exit.

MAX:  the specified maximum thickness value for the structure. This value should be that thickness above which adverse performance characteristics appear, such as mudcracking, embrittlement, solvent retention, loss of adhesion, cohesive splitting, etc. If a maximum thickness value is not specified, set the MAX value to 0. Adjust the displayed value down (-) or up (+). Alternatively, measure a coating with a thickness close to the required value and make final adjustments with the buttons. Press the middle button to save and exit.

#/spot:  the minimum number of individual gage readings required per spot. PA2 suggests a minimum of 3 readings be taken. Adjust the displayed value down (-) or up (+). Press the middle button to save and exit.

spots/batch:  the minimum number of spots (sub-batches) required per batch. PA2 suggests a minimum of 5 spots be measured. Adjust the displayed value down (-) or up (+). Press the middle button to save and exit..

In any measurement there is a certain level of uncertainty. Two people using the same gage will not necessarily record the exact same number for a given spot measurement using the same 4cm (1.5inch) diameter circle. To allow for this natural fluctuation, an individual spot measurement is permitted to be below the specified minimum thickness as long as other spots in the batch area are high enough to make the average thickness meet or exceed the specified minimum thickness. Similar reasoning applies to maximum thickness.

% MIN:  PA2 specifies that no single spot measurement be less than 80% of the specified MIN thickness. The PosiTector 6000 allows this value to be changed if desired. Adjust the displayed value down (-) or up (+). Press the middle button to save and exit.

% MAX:  PA2 specifies that no single spot measurement be more than 120% of the specified MAX thickness. The PosiTector 6000 allows this value to be changed if desired. If the MAX value above has been set to 0, this % calculation is made to the MIN value. Adjust the displayed value down (-) or up (+). Press the middle button to save and exit.

To accept these values but make no change to the operating state of the gage, select Exit. This allows for a handy review of current settings. Changed parameters affect all existing and future batches. The pass/fail standing of stored batches can be changed this way. To accept these values and begin a new PA2 analysis, select NEW. If a PA2 analysis was already begun before entering this set-up, selecting NEW will close/save the existing PA2 batch and begin a new one with a batch name containing the next higher number.

If NEW is selected, a PA2 icon will appear on the gage's display as shown.

Step 3 - Take measurements.

Begin taking measurements in the first SPOT location. With each measurement the following occurs...

1. The green LED blinks, the gage BEEPS twice, and the resultant measurement value is displayed in large numerals at the bottom of the display.

2. The SPOT information is updated
       - "n" is total number of individual measurements taken in the current spot so far.
       - "x" is the average of all measurements in the spot. This is the PA2 spot measurement value.
       -a PASS or FAIL determination is made for the SPOT based on the user-specified parameters

3. The BATCH information is updated
       - "s" is the total number of SPOTS in the BATCH
       - "x" is the average of the spot values   i.e. the "average of the averages".
       - a PASS or FAIL determination is made for the BATCH.

Step 4 - Change the current SPOT or BATCH location.

To move onto the next SPOT location select "New Spot" from the gage menu. (Shortcut: press "+").

To move onto the next BATCH location (begin a new PA2 analysis) select "Memory -> PA2 -> New" from the gage menu..

Step 5 - Review results.

There are 4 ways to look at the results...

1. If all PA2 criteria from Step 2 have been met, the word PASS will appear beside the Batch number, i.e. "B1    PASS".

2. For more detail select "View" from the Memory Menu to display all individual measurements. The last measurement values are displayed first. Scroll using the (-) and (+) buttons. Hold the (-) or (+) button down for 1 second for fast scrolling.
   --To replace a measurement, position the "+" symbol beside the measurement. Then take another measurement with the probe.
   --To delete a measurement or to exit the View screen, press the middle button.

3. All stored measurements can be downloaded to your PC using the included PosiSoft software. PosiSoft allows entry of notes and annotations, it prints and displays basic charts and histograms, it saves measurements to your PC, and it exports measurements to a spreadsheet or documents.

4. Preferred Method:  Print to the optional IR printer or print to a PC's default printer using the included PosiSoft software. All PA2 information is presented including gage serial number, PA2 parameters, individual measurements with date and time stamp, calculated averages, and PASS/FAIL conclusions. This is the best way to ensure that the PA2 specification has been satisfied. See sample .

NOTES:

1. Select the "Delete" menu option to erase a SPOT, a BATCH, or the entire contents of gage memory. PA2 parameters are retained.
2. Select the "Close" menu option to end a PA2 analysis but keep all existing BATCHES, SPOTS and measurements.
3. Calibration adjustments cannot be made while PA2 measurements are stored in gage memory.
4. A gage RESET will restore PA2 parameters back to factory settings (see the instruction manual for RESET details).

The PosiTector 6000's PA2 feature is intended to support the PA2 Application Standard, not replace it. It is the responsibility of the user to read and understand the document, and to verify the accuracy of the gage's conclusions.

What is SSPC?

SSPC was founded in 1950 as the Steel Structures Painting Council, a non-profit professional society concerned with the use of coatings to protect industrial steel structures. In 1997, the name of the association was changed to The Society for Protective Coatings to better reflect the changing nature of coatings technology and the ever-expanding types of construction materials.

SSPC is the only non-profit association that is focused on the protection and preservation of concrete, steel and other industrial and marine structures and surfaces through the use of high-performance industrial coatings. SSPC is the leading source of information on surface preparation, coating selection, coating application, environmental regulations, and health and safety issues that affect the protective coatings industry.

SSPC standards, guides, specifications, and other technical documents are developed in accordance with voluntary consensus procedures established by SSPC Technical Committees. They are intended to represent a balance of interests, and are believed to represent good current practice. All documents are monitored and revised as practices improve.

What is PA2?

The SSPC organization has developed a series of Paint Application Standards, Guides and Specifications. One of them is entitled, "SSPC-PA 2, Measurement of Dry Coating Thickness With Magnetic Gages". It is among the most widely used SSPC standards. (click here to purchase the document).

PA2 describes the procedures to measure the thickness of a dry film of a nonmagnetic coating applied on a magnetic substrate using commercially available magnetic gages. However the described methodology can be used by most non-destructive coating thickness gages including those using eddy-current or ultrasonic principles.

The standard defines a procedure to determine if the film thickness over an extended area conforms to the minimum and the maximum levels specified. This procedure may be modified when measuring dry film thickness on overcoated surfaces.

Contents     Definitions   Description of Gages   Calibration, Verification, Adjustment, and Measurement Procedures   Required number of Measurements for conformance to a thickness specification   Notes on gage principles and various factors affecting thickness measurement   Substrate Roughness, Tacky Films, Curvature, etc.   Variations in Thickness   PA2 was originally developed to analyze large, flat surfaces. But concerns about other shapes and sizes prompted the creation of appendices.     Appendix 1 - Numerical Example of Average Thickness Measurement.   Appendix 2 - Examples of the Adjustment of Electronic Gages using Shims   Appendix 3 - Methods for Measuring Dry Film Thickness on Steel Beams (Girders)   Appendix 4  -similar to Appendix 3 except that the pieces are painted in a shop.   Appendix 5  -Method for Measuring Dry Film Thickness on Coated Steel Test Panels.   Appendix 6  -Method for Measuring Dry Film Thickness of Thin Coatings on Coated Steel Test Panels that Had Been Abrasive Blast Cleaned.

Definitions

Overview

There are several ways to evaluate film thickness with the PosiTector 6000 ...

1. Take a single measurement.

2. Calculate the average of several measurements -- the PosiTector 6000's Statistics mode.

3. Analyze a larger area using a statistical approach -- the PosiTector 6000's PA2 mode.

A large surface usually cannot be characterized accurately by a single measurement. Variations in substrate preparation, painting technique, measuring technique, etc. require an analysis of several measurements taken over a large portion of the surface.

The PosiTector 6000's statistics mode displays individual measurements AND maintains a running average value. It also displays minimum and maximum values.

PA2 The SSPC organization has taken this a step further by developing a specification for structural steel painters. Known as PA2 this specification has become widely used both inside and outside the structural steel painting industry. PA2 helps determine if film thickness over an extended area conforms to user-specified minimum and maximum levels.

It recommends that a coated surface be sectioned into one or more large test areas. A minimum of 15 individual measurements are taken in 5 groups of 3 measurements each. Suggestions are made as to the acceptability of individual measurements, spot measurements (the average of each group), and the calculated average of the spot measurements. In simple terms, PA2 suggests the average of a series of average values be used to determine if a target thickness has been met.

Repeated gage readings, even at points close together, often differ due to small surface irregularities of the coating and the substrate. Therefore PA2 suggests a minimum of three (3) individual gage readings be taken for each spot measurement of the coating. These readings are to be taken within a 4 cm (1.5 inch) diameter circle.

SSPC-PA2 Example

Memory (3) versions of the PosiTector 6000 have a PA2 mode that helps the user collect measurements in conformance with the PA2 standard. Then, based on user-set parameters that include the target thickness, the gage indicates a pass or fail condition.

How does the gage do this?

The PosiTector 6000 has on-board memory into which all measurements are stored. Individual measurements are grouped into "spots" (sub-batches). A series of spots are grouped into "batches". The film thickness result obtained from each batch, the "average of the averages", is taken to be the representative film thickness over the defined area.

The gage continually monitors thickness results and reports a pass/fail condition on the current spot and on the batch as a whole.

Stored results can be viewed on the display, modified or deleted. A formatted printout can be sent to the optional IR printer. Or all results can be downloaded to a PC using the included PosiSoft software and USB cable.

Related Documents:

ASTM D7091-05 “Standard Practice for Nondestructive Measurement of Dry Film Thickness of Nonmagnetic Coatings Applied to a Ferrous Base and Nonmagnetic, Nonconductive Coatings Applied to Non-Ferrous Metals”

ISO 19840:2004 “Paints and varnishes -- Corrosion protection of steel structures by protective paint systems -- Measurement of, and acceptance criteria for, the thickness of dry films on rough surfaces”

Statistics Mode

PosiTector 6000 Standard(2) and Memory(3) gages have a statistics mode. When selected, the gage continuously updates running average and standard deviation calculations. Maximum and minimum values are also tracked while measurements are being taken. The last measurement can be deleted with the (-) button, while the (+) button clears all statistics.

Q&A

Is it possible for all the spots to PASS but for the batch to FAIL?

Yes. The pass/fail criteria for a spot is less stringent than for a batch. PA2 allows spot values to under run the target thickness by as much as 20%. The batch value cannot.

Is it possible to change PASS/FAIL criteria after all measurements have been taken?

Yes. Select the "PA2" menu option, adjust the individual parameters, then select "Exit". All stored PA2 batches will instantly be re-evaluated and a new PASS/FAIL conclusion made.

Can I delete a bad measurement?

Yes. Use the (-) button to delete the last measurement taken. Use the "View" menu option to delete any measurement, spot, or batch. Use the "Delete" menu option to delete spots, batches or the entire contents of memory.

NOTE: the "View" menu option will also allow you to replace measurements.

Must I specify both a minimum and a maximum thickness?

With many of the coatings used today it is a good practice to specify both. This range is usually obtained from the coating manufacturer's technical data sheet. But economic factors along with flow characteristics of the coating usually control excessive film build, so it is common to specify only a minimum thickness. When only a single target value is available, set the MIN to that value and set the MAX to 0.

Can I change PA2 parameters from one batch to the next?
Only one set of PA2 parameters (min, max, #of Spots, etc.) is used by the PosiTector regardless of how many batches you create or how may times you change the parameters. The current set of parameters is used when you create a new batch and start a new PA2 test, and they are applied to all previously created batches. If you change any PA2 parameters, the pass/fail criterion for all previous batches is re-calculated.

PA2 parameters can also be changed after-the-fact by PosiSoft to restore previous settings.

Example:

MIN value is set at 2 mils, Batch 1 is created and readings are taken resulting in a PASS for Batch 1. Then the MIN value is changed to 5 mils, Batch 2 is created and readings are taken resulting in a PASS for Batch 2. But Batch 1 now results in a FAIL because the new MIN value is used. To correct Batch 1…

a) Download to PosiSoft
b) Select “File>Save As” and save the results to Filename1 and save again to Filename2
c) Open Filename 1, delete Batch 2, select “Batch>Edit PA2” to restore the MIN value to 2 mils. Save the file.
d) Open Filename 2; delete Batch 1, save the file.
e) Filename1 now contains Batch 1 with the correct MIN=2mils Filename2 now contains Batch 2 with the correct MIN=5mils