v Air leak survey handbook
Contents
1. Diameter of the Volume of air lost Power required leak at 6 2 bars mm inch L h SCCM SCFM kW 1 6 1 16 3570 59 466 2 1 0 3 3 2 1 8 36 040 600 320 21 2 3 1 6 4 1 4 97 240 1 619 732 57 2 8 3 9 5 3 8 378 250 6 300 533 222 5 33 Information source for this table Atlas Copco Compressed Air Annual cost in electricity for the compressor power supply Pk kWh Cost EUR Cost USD 5 3 7 1196 1 415 10 7 4 2 391 2 830 20 14 7 4712 5 576 30 22 1 7 102 8 405 60 44 2 14 134 16 727 100 73 6 23 628 27 962 150 110 4 35 442 41 943 300 220 8 70 814 83 803 500 368 0 117 998 139 643 700 515 2 165 254 195 567 1000 736 0 236 068 279 370 Base 24h 24h 8 760 h year Price 0 037 kWh 36 8 Some practical advice 1 Use simple screen effect techniques in order to eliminate any parasitic noise Ultrasounds are directional in other words they spread in one direction only Use your body or a piece of cardboard to make a screen between the parasitic ultrasound from the bleed valve for example and the place where you are trying to detect the leak Put a rag or your hand above the sensor in order to indicate the exact location of the leak 2 Be careful of reflection phenomena When looking for a leak it seems sometimes that the leak is coming from a wall a partition the ground or a place where it is obvious that no ultrasound is being created We are t2. is very low only 10 on average taking into account energy leakage motor transmission and compressor losses load losses and leaks The potential for improvement is therefore very great 22 6 Recording the data Recording data relating to each leak inspected is a vital step in your campaign to search out leaks It must be incorporated into your maintenance plan with the option to add records appropriate for your strategy which will meet the objectives of each campaign Example of an internal data record sheet for an inspected leak COMPANY LOGO Detecting compressed air leaks DEPARTMENT sonia MACHINE or premises nesen INSPECTOR coococcococoncononcononccncnnonconincnnnnos SENSOR 4242 dde MEASURING DISTANCE 2 04 200 Date Department Leak Description Size of Loss Air Person Person and number and the leak ofair loss responsible responsible inspector location in dBuV in y anddateof and date of L h repair second check 23 Data recorded for the inspected leak Date and inspector Date and name of the person responsible for checking leaks Department Part of the plant in which the inspection took place e g production workshop packaging unit etc Leak number Number on the leak locating mark Description location Description and location of the leak e g on the left side of the T a
3. and that you have checked the repairs required by previous inspections 12 e KNOWING ALL ABOUT THE NETWORK for yourself and the people involved knowledge of the network compressors the various pressure levels necessary are vital to devising the maintenance plan and observing it e UPDATING THE CONTROL PLANS Keeping the installation diagrams up to date will enable you to devise the most appropriate plan of all the points to be checked All leaks will be recorded there progressively with their precise location their frequency how big they are the type of repair carried out and the check on this CHOICE OF EQUIPMENT It is important to determine precisely the most appropriate sensors and attachments that must be used for each detection point e TRAINING All users of the ultrasound leak detector will have received practical and theoretical training from an experienced person before starting his job e OBSERVING THE 4 STAGES OF THE PROCEDURE The four stages of the programme for looking for leaks must be observed identify locate repair check again e CHECKING REPAIRS To be incorporated into the procedure an ultrasound check of each leak repaired On the one hand the person who checks is not always the one who repairs and on the other hand you have to check that another leak hasn t been created accidentally when working on the network DATA MANAGEMENT Quantifying how much is leaking is a difficult m
4. and the sensor The position and the working angle of the sensor in relation to the leak axis The features of the ultrasound sensor and the conditions under which it is used The temperature and humidity level of the air escaping from the leak and very many more 25 Quantifying compressed air losses also means evaluating the savings made The big question that s asked most often is Looking for leaks is all very well But what good is it going to do me Is it really worth the effort Under certain conditions the method enables each leak detected to be quantified and the gains to be had from its repair to be calculated There is nothing more gratifying that to be able to compile a quarterly or annual table of savings made by your network maintenance services in the certainty that energy efficiency is being managed better and there will be a rapid return on investment In the tables below you will find the values in dBuV measured for a determined compressed air leak whatever the pressure up to 10 bars inclusive e The dBuV measurements in the first two tables are the results of detecting with the internal sensor or the flexible sensor using an SDT 170 S M M or MD unit given that the 170 S model does not have a digital display of the measured value e The dBuV measurements in the third and fourth tables are the results of detecting with the parabolic sensor using one of the units mentioned in the
5. previous paragraph e All SDT detectors have been used in the default 38 4 kHz central frequency band e The dBuV values were recorded at the loudest level of the leak They are therefore maximum values You will note that when using the SDT detector in an industrial environment this noisiest level is rarely detected perpendicular to the leak but most often at an angle of about 30 to the axis of the leak An increase in pressure automatically causes an increase in flow And at the same time the ultrasound signals measured in dBpV by the SDT 170 detector also increase You can therefore favourably deduce from this that quantifying leaks based on the SDT 170 measurements is independent of the level of pressure used not always known 26 Details of the leak used Leak orifice from 0 2 1 mm Area from 0 033 0 822 mm Important note The values in these tables are given as a rough guide and may only be used as guidelines to make the task easier 27 Quantifying a compressed air loss Measurements with the internal SDT 170 sensor or the flexible sensor 1 6 bars inclusive 0 4 m dBuV 90 80 70 60 50 40 30 20 10 o L h o 500 1000 1500 2000 2500 3000 3500 28 20 141 2355 0 083 22 158 2627 0 093 24 176 2931 0 104 26 196 3270 0 115 28 219 3647
6. 0 129 30 244 4069 0 144 32 272 4539 0 160 34 304 5063 0 179 36 339 5648 0 199 38 378 6301 0 223 40 422 7029 0 248 42 470 7841 0 277 44 525 8747 0 309 46 585 9758 0 345 48 653 10885 0 384 50 729 12143 0 429 52 813 13546 0 478 54 907 15111 0 534 56 1011 16858 0 595 58 1128 18805 0 664 60 1259 20978 0 741 62 1404 23402 0 826 64 1566 26106 0 922 66 1747 29123 1 028 68 1949 32488 1 147 70 2174 36241 1 280 72 2426 40429 1 428 74 2706 45100 1 593 76 3019 50311 1 777 29 Quantifying a compressed air loss Measurements with the internal SDT 170 sensor or the flexible sensor 1 10 bars inclusive 2m dBuV O L 0 1000 2000 3000 4000 5000 6000 30 sou wn seem ser 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 225 250 278 310 345 384 428 3745 4169 4641 5167 5753 6404 7130 7938 8837 9838 10953 12194 13575 15113 16826 18732 20854 23217 25847 28776 32036 35665 39706 44205 49213 54789 60996 67907 75600 84165 93701 0 132 0 147 0 164 0 182 0 203 0 226 0 252 0 280 0 312 0 347 0 387 0 431 0 479 0 534 0 594 0 662 0 736 0 820 0 913 1 016 1 131 1 260 1 402 1 561 1 738 1 935 2 154 2 398 2 670 2 972 3 309 31 Quantifying a compressed air loss Measurements with the SDT 17
7. 0 and the parabolic sensor 5 10 bars inclusive 2m dBuV L h 0 1000 2000 3000 4000 5000 6000 32 65 756 12600 0 445 66 855 14250 0 503 67 956 15933 0 563 68 1059 17650 0 623 69 1165 19417 0 686 70 1274 21233 0 750 71 1385 23083 0 815 72 1500 25000 0 883 73 1618 26967 0 952 74 1740 29000 1 024 75 1866 31100 1 098 76 1996 33267 1 175 77 2132 35533 1 255 78 2274 37900 1 338 79 2422 40367 1 426 80 2580 43000 1 519 81 2744 45733 1 615 82 2920 48667 1 719 83 3110 51833 1 831 84 3318 55300 1 953 85 3548 59133 2 088 86 3810 63500 2 243 87 4125 68750 2 428 88 4550 75833 2 678 33 Quantifying a compressed air loss Measurements with the SDT 170 and the parabolic sensor 5 10 bars inclusive 5m dBuV L h i 0 2000 4000 6000 8000 34 56 944 15733 0 556 57 1052 17533 0 619 58 1164 19400 0 685 59 1280 21333 0 753 60 1400 23333 0 824 61 1516 25267 0 892 62 1632 27200 0 961 63 1770 29500 1 042 64 1902 31700 1 120 65 2040 34000 1 201 66 2186 36433 1 287 67 2333 38883 1 373 68 2490 41500 1466 69 2656 44267 1 563 70 2830 47167 1 666 71 3016 50267 1 775 72 3217 53617 1 894 73 3438 57300 2 024 74 3682 61367 2 167 75 3964 66067 2 333 76 4305 71750 2 534 77 4776 79600 2 811 35 Table correlating the diameter of the leak its volume and the loss of energy
8. Guide for ultrasonic leak detection in compressed air systems in an industrial environment Copyright 2007 by SDT International n v s a First edition English version All rights reserved Reproduction in any form of all or part of this document is not permitted without the written permission of SDT International n v s a SDT International n v s a Bd de l Humanit 415 B 1190 Brussels BELGIUM Tel 32 2 332 32 25 Fax 32 2 376 27 07 e mail info sdt be web page http www sdt be Contents 0 PPRPPP UVRPRWNMHM a Detecting compressed air leaks a double edged EA E 5 Pay for the air you use not for leaks unennneenennennn 7 Detecting leaks by listening to the ultrasounds that they Produce ciutat tata aida 9 Implementing a campaign to search for leaks and drawing the most benefit from it 11 Devising an effective strategy nnseensennnennnnnnennnennennnennnen nennen 11 Devising the Procure ce ccecceecceeceeeeeeeecesececececeeeeesaeteneeenetnneeneeees 12 Choosing appropriate detection equipment 14 Using the SDT 170 detector properly nenssenssennsnseennennnennn 16 Leaks but where 2 ceecceeccecccecceeceeceseeeeaeceececececesaeeseeeseeesaeeeneeeetees 19 Detecting a leak oooioodiicincionirsennicccncin iia acinnican hassen 21 Recording the data eccccccecceeeeseeeseeeeeeesecesseeeseeeseeenees 23 Quantifying a comp
9. It is therefore vital to understand what ultrasounds are and how they relate to leaks in order to understand how to detect them properly Sounds and ultrasounds are mechanical vibrations of matter Ultrasound is the same type of vibration as sound but at a frequency higher than 20 kHz which is inaudible to the human ear which has a range of between 15Hz and 20Hz Compared with the diffuse emission of sounds ultrasounds spread in a concentrated fashion in one direction They can be compared with a beam of light whose intensity decreases depending on the distance Ultrasounds are generated naturally by fluid turbulence phenomena caused by pneumatic or hydraulic problems leaks or by friction phenomena caused by mechanical problems Electrical problems such as arcs corona effects etc also generate ultrasounds In the event of a leak from a com pressed air system the air friction that escapes generates ultrasounds on the sides of the perforation And it does this whatever the size of the leak its flow rate and the dimension of the hole however small it is Ultrasounds can also be produced artificially using a transmitter to perform tightness tests for example As the acuity of the human ear is limited it is vital to use a detection instrument to listen to ultrasounds to detect where they are coming from and consequently to locate the leak accurately The SDT 170 ultrasound detector operating principle The SDT 170 det
10. aces in spots that are the most hidden as well as in the most inaccessible places A real proactive programme to seek out this type of waste is more than vital to reduce the loss to a reasonable amount Reducing compressed air losses to 5 of the amount consumed It s all the more true that if losses prevent minimum service pressure being reached you very often tend to increase pressure Which increases the percentage of losses Taking into account the number of components in any compressed air system it is easy to imagine the potential for leaks and the financial benefits of a detection campaign This can be calculated very quickly using the cost of the smallest leaks and by simple multiplication A single 1 mm leak at 6 bars is already costing you 144 per year At 12 bars it will cost you 480 per year Annual costs of energy caused by an undetected leak Loss Loss of air Loss Loss Coste at Core Hole Y of air at at of energy of energy Gare ilo bare mm 6 bars 12 bars in kWh in kWh EUR EUR l s l s at 6 bars at 12 bars 1 1 2 1 8 0 3 1 144 480 1 5 2 6 3 7 0 7 2 0 312 987 2 4 8 7 4 1 2 4 1 576 1 973 2 5 7 5 12 8 1 9 7 5 900 3 413 3 11 1 20 8 3 1 12 7 1 488 6 096 Costs to be multiplied by the number of leaks kWh x 0 06 EUR x 8 000 operating hours per year 3 Detecting leaks by listening to the ultrasounds that they produce Leaks emit ultrasounds
11. air systems Economic issue Environmental issue For each one of us and future generations For every business 2 Pay for the air you use not for leaks Compressed air is the most used energy fluid in industry but also the most expensive Based on 5 years consumption at a rate of 6 000 production hours a year it is generally accepted that compressed air production costs are divided into 75 for the provision of energy 13 investment and 12 maintenance costs Compressed air is expensive for an overall thermodynamic yield use efficiency of hardly 10 even in the best of circumstances Compressed air production takes 2 or 3 place in a company s energy costs It is therefore natural to take its improvement potential into consideration It is important and is based essentially on the ideal balance between actual production requirements and pressure levels on reducing energy losses on maintaining components on checking air quality and eliminating leaks in the network In some companies rather than thinking about these improvements they bring in a compressor to compensate for these losses This is not an unusual situation Leaks may represent 30 40 of the amount consumed You must realise that leaks may occur anywhere in the network online connections bleed valves filters pressure regulators slide gates quick release connections rubber pipes etc And there are still lots more pl
12. al sensor connect the selected sensor to the connection for the external sensor Then connect the headphones to the unit s audio output You must use these to search for the leak to locate it and to be able to quantify it You will also be protected from surrounding parasitic noises Start the apparatus fig 8 page 18 16 3 Ensure that the sensor connected is automatically recognised by the SDT 170 unit The sensor ID is displayed in the top left corner of the screen fig 7 Type of sensor Type of sensor INT SENSOR a An A No displayed value adjustment indicator 1 A 80 f MMMM INT SENSOR cu Measurement unit 2 dBpY Measured value A 3 9 i displayed after A Pur Amplification level pushing Bargraph and peak value Figure 7 The LCD display 4 Check the battery level on the icon in the upper right corner of the screen fig 7 5 After the company safety procedures have been performed you start detecting leaks as described in Chapter 5 All details in the user manual supplied with the unit The importance of the digital display Your SDT detector may be fitted with a screen with a bar graph display or a digital display for measuring the leak More precisely the digital display is vital for quantifying leaks in view of an economic approach following your strategy for finding leaks Apart from the fact that measures can be traced and it is very user friendly there are many advantage
13. atter From feedback from major users and its specialist expertise SDT provides you with a unique approach to quantification Recording such figures with the history of each leak will allow you to compile an annual table of savings generated by your network maintenance They will also encourage the transfer of skills within your business 13 4 3 Choosing appropriate detection equipment As specified in the procedure each check point requires the use of a sensor or the most appropriate fitting Let us always bear in mind that the ultrasound frequency is low energy and that is spreads in a concentrated way and in a single direction The most effective ultrasound sensor corresponds to each control and locating situation The flexible sensor The parabolic sensor For easy to get to places Figure 3 The SDT 170 s internal sensor and the precision attachments The internal detector sensor The EDS Extended Distance Sensor adapter All SDT 170 ultrasound detectors are fitted with an open internal sensor to detect compressed air gas and vacuum leaks It s the ideal sensor for daily searches and for a quick check of easily accessible places opposite the operator Several precision attachments fig 3 nos 2 5 may help to locate exactly where the leak is 14 For difficult to get to places This flexible rod with integral sensor has been designed to detect leaks in places deemed to be inacc
14. d air systems a measure that is within the grasp of any company is an important step in its commitment to an active energy management policy The solution is there It is simple and easy to implement It enables you to make substantial savings and goes well beyond eliminating a great waste of energy And however compressed air is still often forgotten when programmes for reducing production costs are drawn up Andr DEGRAEVE Manager SDT International SDT International s a Bd de l Humanit 415 B 1190 Brussels BELGIUM Tel 32 2 332 32 25 Fax 32 2 376 27 07 e mail info sdt be web page http www sdt be
15. ects ultrasound signals converts them into audible frequencies and amplifies them The aim is to transpose the signal received into an interpretable audible signal using heterodyne technology This solution extends human hearing capacity beyond the audible range into the ultrasound band U V da Figure 1 The main function of the SDT 170 is to convert high frequency signals into audible signals F kHz It must be noted that the detector s central frequency band can be adjusted to a specific frequency between 15 1 and 190 7 kHz the default frequency is 38 4 kHz Minimum Standard Maximum 15 1 2 38 4 2 190 7 2 i i I y F kHz Figure 2 The frequency bands are used depending on the type of sound to be detected For the purposes of detection the SDT 170 detector is only sensitive to ultrasound vibrations It restores the turbulence effects i e the actual sound of the leak and it quantifies this leak in dBuV 10 4 Implementing a campaign to search for leaks and drawing the most benefit from it A proactive campaign for looking for leaks requires devising a schedule for performing services repeatedly over time This is completely different from the prompt unforeseen reactions required by leaks that appear suddenly This proactive campaign involves using the most appropriate tool and attachments for each location observing an appropriate methodology managing the data relating to each leak documented va
16. essible and to get round the parts to be checked In fact it can be bent turned and pointed in any direction Two lengths available 550 and 820 mm Figure 4 The flexible sensor 550 or 820 mm Average distance up to 10 m Generally a large part of the compressed air system is located at ceiling level You need to use a ladder or lifter to inspect it There is an easier way The EDS Extended Distance Sensor allows you to inspect it while keeping your feet on the ground This conical shaped adapter is fitted with a threaded tip It is screwed onto the SDT 170 s internal Dee D sensor and concentrates the ultrasonic frequencies It enables better detection at a medium distance and it improves the accuracy of the approach Figure 5 The EDS Extended Distance Sensor adapter 15 Long distance up to 25 30 m If the place to be inspected or the leak to be located is out of range of the detector in spite of using the EDS fig 5 you can use this parabolic sensor This is a high precision signal concentrator which enables detection at very long distances This transparent plexiglas parabola is fitted with a particularly sensitive sensor It has two sights for extremely accurate location one is a rifle sight and the other a powerful laser sight Figure 6 The parabolic sensor and its laser sight 4 4 Using the SDT 170 detector properly 1 If you don t use the SDT 170 detector s intern
17. hen faced with the laws of reflection Ultrasounds are partially absorbed by the material on which they are reflected and partially reflected by this material When faced with a reflection phenomenon you must estimate the angle of reflection and place yourself in the direction of the angle of incidence the direction the leak is coming from In relation to the reflection surface the two angles are equal When looking for the leak in the direction of incidence the height where it is detected in the headphones should be higher than the height detected in the direction of reflection 3 Absorption of ultrasound As we have already described in the trick above part of the ultrasound signal is absorbed by the object on which the ultrasounds are reflected This absorption factor depends entirely on the material of the object on which the ultrasound signals are reflected A fabric covered surface absorbs the sound much more or reflects it much less than a concrete or metal surface 37 4 Locating a leak precisely It isn t normally enough to stop detecting a leak a few centimetres away from the assumed leak In order to locate the leak precisely you must always check the area surrounding it because the precise location of the leak may be in the same direction as the one you were looking for All the more so if a compressed air system is behind a pipe or a flange This is why it is advisable to carry out an inspection of the area all around the su
18. ir or vacuum leak If the signal detected is too powerful reduce the amplification level to make it more comfortable to work As soon as you detect the hissing sound move the sensor closer to the source to locate the leak Press the down arrow to reduce the signal level given that it will increase as you approach the precise location of the leak 21 3 This will be at the place where the signal is most powerful and when the highest value is displayed on the screen 4 Select the amplification level depending on your working environment so that you do not have either of the two indicator arrows on the screen of the SDT 170 They may still be there when the amplification level is at its maximum A 80 or at its minimum A 10 5 Note down or save the leak measurement dBuV displayed on the screen 6 Report this precise spot if the leak is to be repaired immediately or mark it with a locating mark if it is to be repaired later 7 Note down as much information as possible about the leak the place the type of leak how big it is the identity of the inspector and the repairer are very useful items to note down Compressed air is expensive Compressed air losses waste 1 Controlling this energy vector is an absolute necessity Compressed air is expensive 2 Compressed air costs 0 6 3 0 per Nm depending on the optimisation of the plant 3 The overall thermodynamic efficiency efficiency of use of a plant
19. ise global warming Well if nothing s done these emissions themselves will increase by 60 How much will industry contribute to this While you re watching your energy bills rise not a day goes by without new commitments to reduce CO2 emissions quotas being tackled A double challenge to be taken up by any manufacturer All the more so because at the beginning of 2007 the European Union undertook to reduce these types of emissions by 20 at least between now and 2020 Compressed air leaks are very costly in terms of excess consumption of energy Some awareness skills within everyone s reach and above all good reactions are all that is needed to incorporate energy concerns into one s production tool management Contrary to what you might think managing energy better and or investing in energy efficiency can be very profitable And this doesn t happen very often a solution that involves eliminating leaks has immediate benefits both for the environment and for your finances More generally admittedly measures aimed at protecting the environment will incur some costs In this case on the other hand this is balanced out by the benefits And what is more motivating than combining this with the future of generations to come The detection of leaks in compressed air systems a measure that is within the grasp of any company is an important step in its commitment to an active energy management policy Detecting leaks in compressed
20. lidated repair measures and finally as far as possible quantifying leaks and doing the calculation resulting from the campaign 4 1 Devising an effective strategy The proper management and success of a maintenance programme for your compressed air network is based essentially on the quality of your strategic plan e DEFINE THE OBJECTIVES Defining what the objectives are apart from the main one which is to drastically reduce energy costs by only agreeing to a small investment in a detector is vital Any effective maintenance strategy is necessarily based on a well defined goal Thus the first question to ask yourself is quite logically What objectives must be achieved by applying a maintenance plan to my compressed air network Here are some examples Drastically reduce your energy costs with just a small investment Detect quantify the amount and repair any compressed air leak in the existing system Restrict the overall amount of losses to 5 of the amount consumed Take the strain off your compressors and prolong their lifespan 11 Make all the staff in your company aware of the high cost price of compressed air Train the users involved in the most effective methods for maintaining the compressed air network Etc e MAKE ALL STAFF AWARE To achieve maximum efficiency it is important to make all staff aware of this by posting permanent notices about the objectives These objectives must be
21. nd will convince you to implement a better energy efficiency management programme When people talk about energy saving prospects the idea of protecting the environment is however never very far removed Detecting leaks in your compressed air systems addresses these two concerns An environmental and an economic issue Energy is and will increasingly become an important priority issue because of its price because supplies are running out and because of the constant fight against climate change etc In such conditions why not eliminate completely worthless consumption caused by leaks from compressed air systems Isn t it time to limit the damage Especially in view of the fact that the pledges made under the Kyoto Protocol ratified in February 2005 require us to reduce toxic emissions into the atmosphere by better energy efficiency management By 2012 35 industrialised countries have made a commitment to reduce greenhouse gas emissions by 5 compared with their 1990 levels They represent 35 of global emissions As such this target is far from being enough In addition to this no commitment has been made for after 2012 If you listen to Stephane Dion the retiring President of the United Nations conference on climate changes We would need ten Kyoto agreements to be able to reduce the effects of climate change Scientists are saying that there must be a 60 reduction in greenhouse gas emissions within the next fifty years to stabil
22. ressed air loss run2neenennnnnnn 25 Some practical advice 2 2 ccecceecceeceeeeeeeeeeeeeseeeseeeeeneeees 37 As the indisputable leader in its field SDT International designs and produces a large range of measuring instruments for the ultrasonic detection and evaluation of various other physical parameters The company s expertise covers a vast array of applications large and small capacity tightness tests and for underground tanks the detection of leaks in any pressure system production quality control and the detection of wear and faults in the predictive maintenance of mechanical equipment Our company s success is based on our philosophy and our willingness always to respond to our customers problems with the most effective money saving solutions SD O The Precision of ultrasonic 4 1 Detecting compressed air leaks a double edged issue Detecting leaks in compressed air systems is a double edged issue an environmental one for each one of us and an economic one for every business Is it because it s an environmental issue that so few business managers feel worried about the topic Then let s deal with this issue based on the substantial savings that can be made by eliminating this tremendous waste A proactive ultrasonic leak detection campaign quantifying the amount of compressed air lost can be used to easily calculate the amount of benefit generated The figures then speak for themselves a
23. s from saving data and transferring it to a PC Some versions have this option 17 Cycles through battery level date and time Type of sensor connected NT o Amplification adjustment M a ay 33 Unit of measurement indicators up or down qo Amplification value in dB Measurement value Bargraph display en ee PR sec max value First press acess menus Second press return to previous menu Increase amplification Reduce amplification or move up through menus he or move down through menus Displays peak value while Store measured value button is held down in memory Previous value is cleared when and tunable frequency button is pressed and tunable setting decreasing frequency setting increasing Enter key Press to accept choice O On Off switch Figure 8 The basic functions of the SDT 170 Back light of display switch 4 5 Leaks but where Leaks may occur anywhere in your compressed air system A look at the top twelve most common leaks Connections on the supply line Quick coupler Filters Pneumatic cylinders Regulator dryer assembly Pressure regulators Rubber pipes Regulator lubricator assembly A A E E ES Isolation valves 10 Control valves 11 Automatic drain traps 12 Various pipes As a rough guide the table below gives you the distribution of compressed air used in industry where there is absolutely no proactive predictive network maintenance programme Distribution of the amo
24. spected leak 5 Quantifying leaks To quantify leaks as accurately as possible you must always start from the maximum dBuV value This is equivalent to the highest leak sound detected Only the highest value can be considered recorded in the internal memory and then transferred to the computer By inserting these values in the appropriate Excel lists it becomes easy to calculate the total air loss loss in 38 39 Detecting leaks in compressed air systems is a double edged issue an environmental one for each one of us and an economic one for every business Is it because it s an environmental issue that so few business managers feel worried about the topic Then let s deal with this issue based on the substantial savings that can be made by eliminating this tremendous waste A proactive ultrasonic leak detection campaign quantifying the amount of compressed air lost can be used to calculate the amount of savings made The figures then speak for themselves and will convince you to implement a better energy efficiency management programme Eliminating compressed air leaks has immediate benefits both for the environment and for your finances More generally admittedly measures aimed at protecting the environment will incur some costs In this case on the other hand this is balanced out by the benefits And what is more motivating than combining this with the future of generations to come The detection of leaks in compresse
25. spread around the whole company so that each member of staff comes up against them all the time RECONSIDER THE WHOLE OF YOUR NETWORK Managing a maintenance programme for your network is much more than looking for leaks and making repairs It s also thinking about the network as a whole and making the improvements that are vital for greater efficiency 4 2 Devising the procedure Your procedure must be devised so that it achieves three results the safety reliability and effectiveness of your programme for looking for leaks For optimum management of your compressed air network some procedural steps deserve special attention SAFETY This means compiling a procedural manual Particular attention must be paid to this document It will specify the frequency of inspections for each control point as well as the most appropriate sensor and attachments for each of these points The checking procedure will be detailed in five phases detecting locating quantifying repairing and checking the repair It will also describe how each person involved must record that he has observed the procedure for each phase and also record information about the leak FREQUENCY An effective annual maintenance plan requires 3 4 inspections of all the points of the network Moving parts or those in a hazardous environment will be checked every month You will then ensure that you have detected all new leaks as early as possible after they appeared
26. t the outlet of boiler no XXX or at the inlet to pump no YYYY see diagram Z Size of the leak in dBuV The value measured and displayed on the detector screen Air loss in L hour See tables from page 28 Quantifying a compressed air loss Air loss in year If you have the cost prices of compressed air in your company you can easily estimate the annual financial loss resulting from this leak Person responsible and date of repair Actual date the repair was finished and the name of the person who carried it out Person responsible and date of re check Date the repaired leak underwent a second ultrasound check and the name of the inspector 24 7 Quantifying a compressed air loss Quantifying a leak by converting the dBuV into L y or into SCCM SCFM is to be planned with the greatest care It should only be undertaken by competent people who have been trained appropriately Given that a very large number of factors may influence the taking of measurements in dBuV it goes without saying that the user of this type of measuring equipment will first of all include all of these factors so that he can take account of them when he makes his conclusions on quantifying a detected leak When detecting leaks in an industrial environment certain factors may influence the measurements The leak orifice size its shape its configuration The surrounding parasitic ultrasound signals The distance between the leak
27. unts of compressed air used in industry international averages Consumption by equipment 43 Leaks into the atmosphere 34 Inappropriate uses 16 Purged air 5 Failed drain traps 2 These figures are averages drawn up by Plant Support amp Evaluations Inc Audit Division 19 20 5 Detecting a leak The detection service as such requires the application of some basic principles aimed mainly at efficiency and ease of work e For repeating and comparing measures you will always use the same sensor and or attachment for the same place to be tested e The unit s level of amplification will be selected depending on the working environment e The exact location will be determined by sweeping in all directions searching for the strongest ultrasound signal This is when the highest value appears on the screen It s simple and intuitive given that it s actually the noise of the leak that you are hearing e If it is not to be repaired immediately you will have to provide an exact location of the place e Each repair must be checked as must the immediate sur roundings Procedure 1 Start searching with maximum amplification sweeping from the top to the bottom and from left to right with the unit or the sensor that you have connected to the unit in order to locate the leak accurately Detecting the hissing sound that is typical of ultrasounds indicates that there is a compressed a
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