Elcometer 130 SCM400. Salt Contamination Meter

Transcription

1 English Elcometer 130 SCM400 Salt Contamination Meter Operating Instructions

2 English The Elcometer 130 SCM400 Salt Contamination Meter has been tested in acccordance with EU regulations governing Electro-magnetic compliance and it meets the required directives. is a registered trademark of Elcometer Limited. All other trademarks acknowledged. Copyright Elcometer Limited All rights reserved. No part of this Document may be reproduced, transmitted, transcribed, stored (in a retrieval system or otherwise) or translated into any language, in any form or by any means (electronic, mechanical, magnetic, optical, manual or otherwise) without the prior written permission of Elcometer Limited. Doc.No. TMA-0125 Issue 05 Text with Cover No: 4373

3 CONTENTS Section Page 1 About your meter Standards What the box contains Principle of operation Specification of salt levels Taking a reading Before you start Taking samples using standard sample papers Taking samples using smaller sample papers Interpreting the readings Care and maintenance Checking calibration Checking water quality Checking purity of sample papers Removing and cleaning or replacing the electrodes Removing discolouration from electrode surfaces Replacing the pressure plate support pads Replacing the battery Storage Fault diagnosis Spares and accessories Related equipment Technical specification English 1

4 English T hank you for your purchase of this Elcometer 130 SCM400 Salt Contamination Meter. Welcome to Elcometer. Elcometer are world leaders in the design, manufacture and supply of inspection equipment for coatings and concrete. Our products cover all aspects of coating inspection, from development through application to post application inspection. The Elcometer 130 SCM400 Salt Contamination Meter is a world beating product. With the purchase of this product you now have access to the worldwide service and support network of Elcometer. For more information visit our website at 1 ABOUT YOUR METER The Elcometer 130 SCM400 Salt Contamination Meter measures salt contamination levels on metallic and non-metallic surfaces and is particularly useful on areas such as bends and welds. 1.1 Standards The instrument can be used in accordance with the following International Standard : SSPC Guide What the box contains Elcometer 130 SCM400 Salt Contamination Meter Carry Case and nylon Shoulder Strap High Purity Sample Papers (pack of 100) Plastic Tweezers (2 off) Self-Seal PVC Bags (pack of 20) Replacement Pressure Support Pads (pack of 8) Disposable Gloves (pack of 20) in nylon holdall Pack of Tissues 9 V Alkaline Battery 2 ml Syringes (3 off) Bottle of High Purity Water (250 ml) Plastic Sample Bottle Operating Instructions 2

5 2 PRINCIPLE OF OPERATION Soluble salts on the surface are taken into solution by placing a wetted 110 mm diameter Elcometer 130 SCM400 High Purity Sample Paper on the area to be sampled. By leaving the paper in contact for a timed period, salt removal from the surface is maximised. Using a paper of known size allows contamination to be expressed in terms of surface area. These papers retain a known amount of water because of their consistent absorbency characteristics and therefore the concentration of the solution formed is related to the quantity of soluble salts removed. The sample paper containing the salt solution is placed over the electrodes on the Elcometer 130 SCM400 and its resistivity is determined. This is achieved by measuring the minimum resistance of the solution over a fixed solution path length and cross section, governed by the electrode spacing and paper thickness respectively. The solution concentration is inversely proportional to its resistivity. The Elcometer 130 SCM400 relates the latter to a calibration with known English 3

6 English concentrations of sodium chloride solution and the known surface area sampled, to give surface salt levels in µg.cm -2. Figure 1. Elcometer 130 SCM400 Salt Contamination Meter 3 SPECIFICATION OF SALT LEVELS Ideally, the salt level remaining on a steel surface after surface cleaning and prior to painting or any other construction operation, should be zero. In practice it is not possible to achieve this due to various environmental factors and a working salt level needs to be specified. In the case of painting, this level is a matter for discussion between the Client, the Applicator and the Paint Manufacturer and it will depend on the working conditions, the paint system used, the required service life and what can be economically achieved. Consequently, it is not possible to specify in these Operating Instructions which salt standards are best suited to all industries. However, during the development of the Elcometer 130 SCM400, the effect of salt contamination on the life of coatings under a range of realistic and accelerated environmental conditions for a number of common generic coating systems was assessed. 4

7 Although Elcometer would not wish to recommend this as a specification, the work has shown that a salt level of better than 4 µg.cm -2 is a sensible working limit. 4 TAKING A READING English 4.1 Before you start Is the electrode (Figure 1) clean? See Removing and cleaning or replacing the electrodes on page 14. Is the sampling water to the correct specification, i.e. BS 3978 (ISO 3696) - Water for Laboratory Use, Grade 3? See Spares and accessories on page 18 for replacement water If the sample area is larger than the Elcometer 130 SCM400 High Purity Sample Paper, follow procedure 4.2. If the sample area is smaller than the Elcometer 130 SCM400 High Purity Sample Paper, follow procedure Taking samples using standard sample papers 1. Put on a pair of clean disposable gloves. 2. Fill a 2 ml syringe with precisely 1.6 ml of high purity water. 3. Using tweezers, remove an Elcometer 130 SCM400 High Purity Sample Paper a from the pack. If the standard 110 mm diameter sample paper is too large for the area to be sampled, smaller papers may be used - see Taking samples using smaller sample papers on page 8. a. Use only Elcometer 130 SCM400 High Purity Sample Papers. Commercial filter papers are not suitable as they can contain excessive salt levels. 5

8 English 4. Using the tweezers to hold the sample paper, eject 1.6 ml of water onto its surface (Figure 2), taking care to retain as much water as possible on the paper.. Figure 2. Applying Water to Elcometer 130 SCM400 High Purity Sample Paper 5. Place wetted paper on the area to be sampled, pressing it firmly into its contours and surface irregularities. 6. Press out as much entrapped air as possible from beneath the paper. If hand pressure is required to exclude air, the gloved hand should not be used. Instead, turn one of the plastic bags provided inside out, place it over the gloved hand and press the surface, discarding the plastic bag when finished. 7. Switch the Elcometer 130 SCM400 on by pressing the red pushbutton once b. The display will show: SCM...Ready 8. When the sample paper is in position, press the red pushbutton again to start the 2 minute timer c. The display will show: TIMER STARTED b. When SCM Ready, SALT LEVELS TOO LOW or SALT LEVEL>20 µg.cm -2 is displayed, the instrument will automatically switch off if not used within 20 seconds. 6

9 9. When 2 minutes have elapsed the Elcometer 130 SCM400 emits an intermittent bleep and the display shows: SAMPLE READY English 10.Remove the sample paper from the surface. 11. Place the sample paper over the concentric copper electrodes (Figure 3) ensuring that the outer ring is completely covered. All air must be excluded from beneath the paper. Figure 3. Placing Elcometer 130 SCM400 High Purity Sample Paper onto the Electrode for Measurement 12.Close the lid, ensuring that the magnetic catch is fully engaged. 13.Within 5 seconds, press the green pushbutton and a reading will be displayed:- or:- SALT LEVEL 9 µg.cm -2 SALT LEVELS TOO LOW > 20 µg.cm -2 If Salt Level <0.1 µg.cm -2 If Salt Level >20 µg.cm -2 c. The Elcometer 130 SCM400 cannot be switched off when the timer is operating or when measurements are being made. 7

10 English 14.Lift the lid and remove the sample paper. The sample paper may be kept in one of the resealable bags for further chemical analysis. 15.When all samples have been taken, switch the instrument off by pressing the red pushbutton twice in quick succession. 16.Close the lid and ensure that the magnetic catch is fully engaged. 4.3 Taking samples using smaller sample papers If the standard 110 mm diameter High Purity Sample Papers are too large for the area to be sampled, half size, quarter size or 22 mm wide strip papers can be used as follows. Care must be taken to ensure that sample papers do not become contaminated. 1. Put on a pair of clean disposable gloves. 2. Using tweezers, remove an Elcometer 130 SCM400 High Purity Sample Paper from the pack. 3. Fold paper as follows:- For half size paper fold standard paper in half and cut into two along fold line. For quarter size paper fold standard paper into quarters and cut into quadrants along fold lines. For 22 mm wide strip fold standard paper into half and cut 11 mm either side of fold line. 4. Fill a 2 ml syringe with an appropriate amount of high purity water:- For a half size paper use 0.8 ml For a quarter size paper use 0.4 ml For a 22 mm wide strip use 0.4 ml 5. Holding sample paper in tweezers, eject the correct amount of water onto its surface. Take care to retain as much water as possible on the paper. 6. Follow Steps 5 to 10 (inclusive) in Section Using the central marker on the inner electrode to aid positioning, place the sample paper over the concentric electrodes as appropriate, ensuring all entrapped air is removed: 8

11 If using half size papers - cover exactly half the inner and outer electrodes. Outer Electrode Inner Electrode Half Size Sample Paper English Central Marker If using quarter size papers - cover exactly quarter of the inner and outer electrodes. Quarter Size Sample Paper Outer Electrode Inner Electrode Central Marker If using 22 mm wide strips - lay the paper across the inner and the outer electrodes, to completely cover the inner electrode. 22 mm Wide Sample Paper Outer Electrode Inner Electrode Central Marker 8. Close the lid ensuring that the magnetic catch is fully engaged. 9. Within 5 seconds, press the green pushbutton once to obtain a reading. 10.Multiply the reading by an appropriate factor to account for the reduced area sampled:- For half size paper multiply the reading by 2 For quarter size paper multiply the reading by 4 For 22 mm wide strips multiply the reading by Follow Steps 5 to 10 (inclusive) in Section

12 English 4.4 Interpreting the readings In most practical situations where measurements of surface salt contamination are required, it is unlikely that the precise ionic make-up of the contamination will be known. The Elcometer 130 SCM400 is calibrated against known concentrations of the most common constituent of atmospheric contamination, namely sodium chloride. However, the specific resistivities of other contaminating salts do vary slightly from that for sodium chloride and could give lower or higher readings. To determine the accuracy of readings when the contamination does not consist entirely of sodium chloride, test measurements have been made on the instrument with salt mixtures which are known to be present on atmospherically contaminated surfaces: Simulated Marine Contamination BS 3900: Part F4 (Salt Spray) 76.8% w/o sodium chloride 9.6% w/o magnesium sulphate 6.9% w/o magnesium chloride 3.2% w/o calcium chloride 2.1% w/o potassium chloride 0.8% w/o sodium bromide 0.6% w/o sodium bicarbonate Simulated Urban Contamination 41% w/o ammonium sulphate 37% w/o sodium sulphate 12% w/o sodium chloride 10% w/o sodium nitrite The results are compared with sodium chloride (Figure 4) in terms of Actual Salt Level vs Salt Level Indicated on the Elcometer 130 SCM400. This shows that the difference between readings for these salts and for sodium chloride are acceptably small, particularly at levels of most interest, i.e. those below 10 µg.cm

13 If the exact make-up of the contaminant is known, calibration curves shown in Figure 4 can be produced with solutions of known concentration. These can be used to interpret readings more accurately. 20 SODIUM CHLORIDE English MARINE CONTAMINATION URBAN CONTAMINATION SALT LEVEL READING (µg cm -2) ACTUAL SALT LEVEL (µg cm -2) Figure 4. Readings obtained with Different Salts (All Measurements taken at 25 C) Temperature could affect readings taken. The Elcometer 130 SCM400 has been calibrated with sodium chloride at 25 C. Figur e 5 illustrates the small variation that might be expected in the range 15 C to 35 C. In most cases it is likely that this variation will not be significant. However, the temperature can be corrected by using the graphs given in Figure 5 and as detailed in Technical specification on page 19. The proportion of the soluble salt present on the surface being tested which is removed by the sample paper will also affect readings. This factor is common to all surface sampling methods. Tests have shown that removal rates are as follows:- Smooth machined surfaces: >95% Grit blasted steel (to Swedish Standard >85% Sa3) with a surface profile of 100 µm: For coarser surface finishes: 70% (approximately) 11

14 English If surfaces are heavily pitted (i.e. >1000 µm) it is possible that soluble salts will be retained within the pits. If so, following the qualitative Potassium Ferricyanide test (BS Appendix G) would aid interpretation on carbon steel and low alloy steel surfaces. This test will only work on ferritic steel surfaces C 25 C C SALT LEVEL READING (µg cm -2) ACTUAL SALT LEVEL (µg cm -2) Figure 5. Readings obtained at Various Temperatures with Sodium Chloride 12

15 5 CARE AND MAINTENANCE The Elcometer 130 SCM400 does not contain any user-serviceable components. In the unlikely event of a fault, return the Elcometer 130 SCM400 to your Elcometer supplier or directly to Elcometer. The warranty will be invalidated if the instrument has been opened. Contact details can be found: On the outside cover of these operating instructions. At Please note that the back plate of the Elcometer 130 SCM400 should not be removed by the User - doing so could affect the calibration. English 5.1 Checking calibration The Elcometer 130 SCM400 has been factory calibrated and cannot be calibrated by the User. However, it is possible to check that the instrument is measuring correctly. To do this, take samples as detailed in Taking samples using standard sample papers on page 5, but using precisely 1.5 ml of a solution of 31.6 mg (±0.1) analar sodium chloride, dissolved in 100 ml of high purity water. The reading should be in the range 5 µg.cm -2 (±10%) at 25 C. For temperatures below 25 C apply a correction factor of -1.7%/ C. For temperatures above 25 C apply a correction factor of +1.7%/ C. Note: When finished, thoroughly clean the syringe using high purity water. 5.2 Checking water quality Water quality can be checked on the Elcometer 130 SCM400 as follows:- 1. Switch the Elcometer 130 SCM400 on by pressing the red pushbutton once. The display will show:- SCM...Ready 2. Eject 1 ml of the water in question onto the electrode surface using the 2 ml syringe (Figure 2). 3. Close the lid and press the green pushbutton. 4. If a reading other than SALT LEVELS TOO LOW is obtained, then the water purity is not adequate for use with the Elcometer 130 SCM400 13

16 English 5.3 Checking purity of sample papers Sample papers can be checked as follows:- 1. Put on a pair of clean disposable gloves. 2. Fill the 2 ml syringe with precisely 1.5 ml of high purity water. 3. Using tweezers, remove the sample paper to be checked from the pack. 4. Use tweezers to hold the sample paper and eject 1.5 ml of high purity water onto its surface, retaining as much water as possible on the paper (Figure 2). 5. Switch the Elcometer 130 SCM400 on by pressing the red pushbutton once. The display will show:- SCM...Ready 6. Place the sample paper on the concentric electrodes and follow steps 5 to 10 (inclusive) in Section 4.2. If a reading other than SALT LEVELS TOO LOW is obtained the sample paper is too contaminated for use and should be discarded. 5.4 Removing and cleaning or replacing the electrodes 1. Remove the electrode and gasket by releasing the four retaining screws (Figure 6). 2. To clean the electrode: Wipe the electrode, gasket, pressure plate and the electrode well with clean tissues, ensuring all are properly dry. 3. When refitting or replacing the electrode ensure that the four retaining screws are below the surface of the electrode. 5.5 Removing discolouration from electrode surfaces During use, the electrode will become slightly discoloured due to surface oxidation. This does not significantly affect operation of the Elcometer 130. However, long term use may create heavier corrosion of the electrode surface. This will be particularly obvious on the central electrode where a dark brown ring will form, initially at the edge of the electrode and gradually increasing in surface coverage. This could slightly affect the accuracy of the Elcometer 130 SCM400 and should be removed by gentle rubbing with a very fine abrasive paper (1200 grit). Over a period of time, or by rubbing too hard with the abrasive paper, the electrodes may become damaged and should then be replaced - see Removing and cleaning or replacing the electrodes on page

17 5.6 Replacing the pressure plate support pads The pressure plate is held in position by a series of self adhesive support pads between the plate and the underside of the lid (Figure 6). These pads ensure that the correct pressure is applied to the sample paper surface by the pressure plate. If these pads lose their adhesive properties they can be replaced as follows:- 1. Gently lever the pressure plate away from the lid. 2. Remove the remains of the support pads. 3. Remove any remaining adhesive with methylated spirits. 4. Remove the protective paper from one side of four replacement pads. 5. Place them on the underside of the lid in the same places as the old ones were removed from. 6. Remove the protective paper from the other side of the pads carefully position the pressure plate in the centre of the lid recess. 7. Apply firm pressure to the plate to achieve adhesion. 8. Thoroughly clean the electrode and pressure plate surfaces - see Removing and cleaning or replacing the electrodes on page 14. English 5.7 Replacing the battery It is essential that alkaline batteries d are used in the Elcometer 130 SCM400. The battery compartment is under the name plate on the underside of the instrument. Replace the battery by removing the six screws and fit the new battery, ensuring correct polarity. 5.8 Storage This meter incorporates a Liquid Crystal Display. If the display is heated above 50 C (120 F) it may be damaged. This c an happen if the meter is left in a car parked in strong sunlight. d. Alkaline batteries must be disposed of carefully to avoid environmental contamination. Please consult your local environmental authority for information on disposal in your region. Do not dispose of any batteries in fire. 15

18 English Figure 6. Replacement parts 16

19 6 FAULT DIAGNOSIS There are no User serviceable parts inside this instrument and the back plate should not be removed. If faults of this nature are suspected, please contact Elcometer or your local Elcometer supplier. Faults that may occur which can be corrected by the User are detailed in the Table below. English Fault Cause Remedy Erratic salt level readings Replace Battery message Salt level readings are indicated when no sampling paper is on the electrode Pressure plate becomes detached Salt level readings are higher than expected Electrodes are heavily discoloured Battery level too low Battery level too low Water may be underneath the electrode Support pads have lost their adhesion Contaminated pressure plate or electrode Water conductivity is too high (i.e. >0.25 µs.cm -1 ) Sample papers are contaminated Oxidation/corrosion due to salt solutions Replace battery. See Section 5.7 Replace battery. See Section 5.7 Remove and dry electrode. See Section 5.4 Replace support pads. See Section 5.6 Clean the surface of the electrode and pressure plate. See Section 5.4 Check the quality of the water. See Section 5.2 Check the sample papers. See Section 5.3 Thoroughly clean the electrode. See Section

20 English 7 SPARES AND ACCESSORIES High Purity Sample Papers: T (pack of 100) Disposable Gloves: T Self-Seal Plastic Bags: T (pack of 100) Tissues: T ml Syringe: T Set of Plastic Tweezers: T ml High Purity Water: T to BS 3978 Electrode: T Pressure Plate: T Pressure Plate Support Pads: T (pack of 8) 8 RELATED EQUIPMENT In addition to the Elcometer 130 SCM400 Salt Contamination Meter, Elcometer produces a wide range of other equipment for testing and measuring the characteristics of coatings. Users of the Elcometer 130 may also benefit from the following Elcometer products: Elcometer 134A Chloride Ion Test Kit for Abrasives Elcometer 134S Salt Detection Kit for Blast Cleaned Surfaces Elcometer 134W Chloride Ion Test Kit for Water/Liquids Elcometer 138 Bresle Kit and Patches Elcometer 138/2 Surface Contamination Kit For further information contact Elcometer Limited, your local supplier or visit 18

21 9 TECHNICAL SPECIFICATION Chemical Measuring range: Resolution: Measuring accuracy: 0.1 µg.cm -2 to 20 µg.cm -2 soluble salt (as sodium chloride) when using recommended High Purity Sample Papers and water with a conductivity of <0.25 microsiemens 0.1 µg.cm -2 (with sodium chloride) ±10% of reading Temperature correction: Calibrated at 25 C Below 25 C: -1.7% / C Above 25 C: +1.7% / C English Electrical Electrodes: Display: Sampling timer: Battery: Timeout: Copper 20 digit LCD 2 minutes 9 V Alkaline PP3 (6LR61) 20 seconds Working limits Temperature range: 5 C to 40 C Maximum relative humidity: 80% Physical Dimensions: Weight: Case: Sealing: Sampling capability Substrate: Area required: Position: 200 mm x 190 mm x 60 mm 1.5 kg Damage resistant polyurethane Splash proof Metallic or non-metallic 110 mm diameter Any horizontal, vertical, curved or inclined surface where sample paper can be placed 19

22 20 English