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Elcometer Protovale CoverMaster CM52 Operating Instructions Manual

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Elcometer P350
Protovale CM52
Covermeter
Operating Instructions

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Summary of Contents for Elcometer Protovale CoverMaster CM52

  • Page 1 Elcometer P350 Protovale CM52 Covermeter Operating Instructions...
  • Page 2 This product meets the emc directive 89/336/EEC, amended 92/31/EEC and 93/38/EEC. The Elcometer P350 (CoverMaster CM52) has been tested in accordance with EU regulations governing Electromagnetic Compliance and it meets the required directives. Note - performance may be affected if the unit is operated within a radio frequency electromagnetic field strength greater than 3V/m.

  • Page 3: Table Of Contents

    ® Protovale CM52 Covermaster USER MANUAL 1. INTRODUCTION....................2-5 1.1 In this manual..................2 1.2 The CM52 CoverMaster ............... 2 1.3 Connecting up..................3 1.4 Recharging batteries ................3 1.5 Safety ....................4 1.6 Connecting headphones............... 5 1.7 Compatibility with the CM5 ..............5 2.

  • Page 5: Introduction

    1. INTRODUCTION 1.1 In this manual This manual is divided into 6 major sections. Section1 – INTRODUCTION – Basic features of the CM52 CoverMaster Section2 – PRINCIPLE OF OPERATION – How the CM52 CoverMaster works Section3– LOCATING REINFORCING BARS– How to use the CM52 CoverMaster to locate reinforcing bars in a variety of situations.

  • Page 6: Connecting Up

    Figure 1 shows the front panel of the CM52 CoverMaster. The main features are – ZERO control, which is turned fully anticlockwise to switch the unit OFF MODE switch, which has four positions – LOCate CALibrate DEPth DEPth+audio DIAMeter knob, for selecting bar diameter Centre-zero analogue meter Digital display (LCD) HEAD connector for the search head...

  • Page 7: Safety

    The red indicator on the charger module will light to show that charging is taking place. If the indicator does not light, check that - The charger plug is fully inserted in the rear-panel socket The charger module is correctly plugged into the mains socket The mains supply is switched on The ZERO knob is fully on the OFF position The fuse in the charger module (UK model) is intact.

  • Page 8: Connecting Headphones

    Figure 2a Rear panel and charger socket Protection against water and dust In its leather case, the CM52 CoverMaster can be operated in rainy conditions and is protected against water and dust ingress to IP54 standard. Immersion in water may damage the instrument, but does not create a hazard to the operator.

  • Page 9: Principle Of Operation

    2. PRINCIPLE OF OPERATION The CM52 CoverMaster detects a reinforcing bar by briefly magnetising it, and then detecting the induced magnetic field as it dies away. The strength of the induced field depends mainly on the depth of the bar below the search head, and to a lesser extent on the diameter of the bar.
  • Page 10 Depth measurements MUST be made using the orientation of the search head that produces the strongest signal. Section 3 of this manual is devoted to techniques for locating buried reinforcing bars and placing the search head in the correct position for an accurate depth measurement.

  • Page 11: Locating Reinforcing Bars

    3. LOCATING REINFORCING BARS 3.1 Practice and training Because the CM52 CoverMaster is unaffected by the nature of the material covering the reinforcing bars, the easiest way to practice location techniques is to use uncovered bars which you can see. A block of wood or plastic of 30 to 45mm thickness can be held between the search head and the bars to simulate the depth of concrete cover.

  • Page 12: Basic Search Technique

    Practice how to place the centre-line of the search head exactly over the centre-line of the bar. Use the audible tone to locate the bar, and the digital display for fine adjustment. To maximize the signal, move the search head from side to side, and also rotate it slightly.

  • Page 13: Welded Mesh And Joined Bars

    6. Carefully identify the locations of maximum signal, and mark and join up the positions of the transverse bars as before. 7. Turn the search head back to its original orientation and re-scan the lengthwise bars to make sure that none of the signals were false indications from transverse bars.
  • Page 14 Very strong signals are obtained when the search head is across the centre bar of a double or ‘figure-of-eight’ loop (Figure 7: left) but these locations must not be used for cover measurements - see section 4. Minimum signals are obtained as before when the search head is over the centre of a single loop (Figure 7: centre), and ordinary-strength indications when the head is accurately aligned with the middle of a side (Figure 7: right).

  • Page 15: Measuring Depth Of Cover

    4. MEASURING DEPTH OF COVER 4.1 How the CM52 CoverMaster works The CM52 CoverMaster measures depth of cover from the strength of the eddy current ‘echo’ signal. The stronger the signal, the shallower the cover or the larger the bar diameter.

  • Page 16: Irregular Bars

    8. If an audible indication is not required, switch the MODE control back to DEPth. CAUTION – Whenever possible, use the audible indication until you are absolutely certain of the layout of the reinforcing bars. Having the audible indication sounding does NOT significantly decrease operating hours. 4.3 Irregular bars The CM52 CoverMaster is factory-calibrated for round ribbed high-tensile bars, and correctly indicates the minimum depth of cover from the surface to the closest peaks of...

  • Page 17: Advanced Techniques

    5. ADVANCED TECHNIQUES 5.1 Search method for congested situations When the reinforcing bars are laid in an unknown pattern, especially if they are close together or are partly joined by wires or stirrups, this can create difficulties in locating the bars and measuring their depths.

  • Page 18: More About Transverse Bars

    CAUTION – 1. When scanning for under-cover, the display does not measure cover. 2. The unit may signal a bar of adequate cover but larger size. 3. The unit may not signal an under-covered bar of smaller diameter. 4. The unit will not signal a bar which is completely missing! 5.4 More about transverse bars Reinforcing bars lying transverse to the bar being measured will produce some additional signal, and hence will cause the depth of cover to be underestimated.

  • Page 19: Depth Measurements In Congested Situations

    1. If the transverse bar is more than 10-20mm beyond the narrow end of the search head (depending slightly upon the size of the bar and the depth of cover), there is no significant error. 2. When the transverse bar is exactly beneath the centre of the search head, and exactly at right-angles to it, the error in a cover measurement is generally 1mm or less.
  • Page 20 Thus the possibility of errors due to adjacent bars is greater when the bars are further away from the search coils. This also applies when the head is turned over to use the white face in congested situations– the extra 30mm separation will make the measurement more susceptible to errors caused by adjacent bars.
  • Page 21 By far the most serious cause of unwanted signals from other bars is misalignment of the search head by the user. This can be avoided by ensuring that the following conditions are met when making a cover measurement. 1. The search head must be exactly parallel to the target bar. 2.
  • Page 22 Figure 11 Effects of congestion on accuracy of cover measurements Key — Situation Effect upon cover readings Unconnected bars Welded mesh fabric Correct correct correct Not over bar very high high Not parallel to bar very high Over transverse bar slightly low very low Close parallel bars...

  • Page 23: Closely-Spaced And Lapped Bars

    5.6 Closely-spaced bars If the head is scanned lengthwise along a bar whose location has already been accurately determined, the signal should stay constant unless the head is moving over either a transverse bar or a lapped join. Section 5.4 dealt with transverse bars, which have a characteristic double-humped response (Figure 8).

  • Page 24: Reinforced Concrete Pipes And Pillars

    5.8 Reinforced concrete pipes and pillars Reinforced concrete pipes and pillars contain a cage of reinforcement, made from typically six lengthwise bars and a continuous spiral, all welded together. Larger pipes or round pillars may contain two or more concentric cages. Cover measurements on the ends of pipes can be regarded as essentially accurate.
  • Page 25 Figure 12 Reference graph for recommended method of estimating bar size...
  • Page 26 4. Remove the spacer, or turn over the search head, and note the maximum possible direct reading from the black face. This should not exceed 1.900 5. If the spaced reading is less than 0.030 , reduce the DIAM setting and try again. If the direct black-face reading is greater than 1.900 , increase the DIAM setting and try again.
  • Page 27 Figure 13 Example worksheet...
  • Page 28 Please note that the results of this bar-sizing procedure can be significantly affected by the presence of neighbouring bars. Before attempting to estimate a bar-size, the location of all bars should have been mapped out, so that a suitable measurement position can be selected.

  • Page 29: Materials Other Than Reinforcing Bars

    Method B for estimating bar size This method is based on the recommendations of British Standard 4408:1:1969, repeated in BS1881:204:1988. The CM52 CoverMaster has been designed to be relatively insensitive to the diameter of the bar, and while this is a major operational advantage over other types of instrument, the success of the BS method becomes very dependent on accurate zeroing before every measurement.

  • Page 30: Magnetic Aggregates

    Non-magnetic metals Signals from copper and brass are weaker then those from ordinary iron and steel. To obtain sufficient signals for location and depth measurement, the DIAM control needs to be set to a much lower value than the true diameter. The optimum value must be determined by experiments with uncovered samples.

  • Page 31: Midget Head

    5.12 Midget Head A midget head is available from Protovale, with dimensions nominally half those of the standard head. It is intended to measure covers from 6 to 30mm to an accuracy of typically ±1mm. The intended application is for measuring covers which are consistently just under 30mm, without the need to use the white face of the standard head, thereby avoiding the possible loss of accuracy which can occur in congested situations as described in sections 4.4 and 5.5, which would otherwise have required an additional 10mm spacer.

  • Page 32: Data-Logging

    5.13 Data Logging. The CM52 CoverMaster is supplied fitted with an output suitable for feeding into any commercially-available data-logger. This analogue output socket is mounted on the left-hand side of the case (of the two sockets, it is the one further from the front panel), and is a 3.5mm mono jack with the inner (tip) being signal positive and the outer (sleeve) negative ground.

  • Page 33: Recalibration

    6. RECALIBRATION The CM52 CoverMaster is calibrated for ribbed high-tensile steel bars, since these are the type most commonly used. Since the accuracy of cover measurements for bars which are smooth and/or made from mild steel is generally within ±5%, recalibration for those purposes is usually not necessary.

  • Page 34: Intermediate Checks

    6.3 Intermediate checks 1. Carry out the quick check as described in section 6.1. 2. Use a T16 high-tensile bar and only a 60mm spacer, carry out part of the full check (section 6.2). 3. Use the 60mm spacer and the additional 30mm spacing of the white face of the search head for a third check at a total spacing of 90mm.
  • Page 35 Do not dispose of any batteries in fire. PACKAGING This elcometer product is packed in a cardboard package. Please ensure that this packaging is disposed of in an environmentally sensitive manner. Please consult your Local Environmental Authority for further guidance.
  • Page 36 Fax: +49 (0)7366 91 92 86 e-mail: sales@elcometer.com e-mail: de_info@elcometer.de www.elcometer.com www.elcometer.de SINGAPORE Elcometer Inc. Elcometer (Asia) Pte. Ltd. 1893 Rochester Industrial Drive, 896 Dunearn Rd, Rochester Hills, Michigan 48309 Sime Darby Centre #03-09, Tel: +1 248 650 0500 Singapore 589472,...

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