[{"data":1,"prerenderedAt":564},["ShallowReactive",2],{"site-footer-common":3,"glossary:acoustic-impedance":45,"glossary-related:acoustic-impedance":138},{"id":4,"extension":5,"footer":6,"meta":40,"navbar":41,"stem":43,"__hash__":44},"common\u002Fcommon.yml","yml",{"tagline":7,"links":8,"sections":9},"Acoustic cleaning intelligence for industrial fouling, soot, ash, dust and build-up.",[],[10,19,31],{"title":11,"links":12},"Product",[13,16],{"label":14,"to":15},"How it works","\u002F#product",{"label":17,"to":18},"Cost assessment","\u002F#hero",{"title":20,"links":21},"Company",[22,25,28],{"label":23,"to":24},"What we build","\u002F#about",{"label":26,"to":27},"Careers","\u002F#careers",{"label":29,"to":30},"Contact","\u002F#contact",{"title":32,"links":33},"Resources",[34,37],{"label":35,"to":36},"Blog","\u002Fresources\u002Fblog",{"label":38,"to":39},"Glossary","\u002Fglossary",{},{"links":42},[],"common","YocmZRy1AYfBbpgGVms-zhdiABlF8VTxHx6h4rDmZBA",{"id":46,"title":47,"aliases":48,"body":51,"category":119,"description":120,"extension":121,"meta":122,"navigation":123,"path":124,"relatedTerms":125,"seo":129,"sources":132,"stem":136,"term":47,"__hash__":137},"glossary\u002Fglossary\u002Facoustic-impedance.md","Acoustic impedance",[49,50],"characteristic impedance (acoustic)","specific acoustic impedance",{"type":52,"value":53,"toc":112},"minimark",[54,61,66,80,84,87,91],[55,56,57,60],"p",{},[58,59,47],"strong",{}," is the resistance a medium offers to the flow of acoustic energy. It is the product of medium density and the local speed of sound and is measured in pascal-seconds per metre (Pa·s\u002Fm). When sound travels from one medium to another with different impedance, a fraction of the energy is reflected at the interface — the larger the mismatch, the more is reflected.",[62,63,65],"h2",{"id":64},"why-bell-horns-exist","Why bell horns exist",[55,67,68,69,74,75,79],{},"A bare pneumatic ",[70,71,73],"a",{"href":72},"\u002Fglossary\u002Fdiaphragm-horn","diaphragm"," is small, stiff and presents a high acoustic impedance. The open volume inside an ESP or boiler is large and low-impedance. A direct coupling would reflect most of the diaphragm's energy back to itself instead of radiating it into the vessel. The ",[70,76,78],{"href":77},"\u002Fglossary\u002Fbell-horn","bell horn"," is an impedance-matching transformer: its exponential flare gradually steps the impedance down from the throat to the mouth, letting acoustic energy escape efficiently into the gas.",[62,81,83],{"id":82},"why-air-to-metal-interfaces-reflect-almost-everything","Why air-to-metal interfaces reflect almost everything",[55,85,86],{},"Air has an acoustic impedance of roughly 410 Pa·s\u002Fm; steel is roughly 47 million Pa·s\u002Fm — a five-order-of-magnitude mismatch. Sound waves striking a metal tube reflect with essentially no transmission. Cleaning energy therefore couples to deposits via gas-borne pressure variation, not by transmission into the metal.",[62,88,90],{"id":89},"related-terms","Related terms",[92,93,94,100,106],"ul",{},[95,96,97],"li",{},[70,98,99],{"href":77},"Bell horn",[95,101,102],{},[70,103,105],{"href":104},"\u002Fglossary\u002Fsound-pressure-level","Sound pressure level",[95,107,108],{},[70,109,111],{"href":110},"\u002Fglossary\u002Fattenuation-acoustic","Attenuation (acoustic)",{"title":113,"searchDepth":114,"depth":114,"links":115},"",2,[116,117,118],{"id":64,"depth":114,"text":65},{"id":82,"depth":114,"text":83},{"id":89,"depth":114,"text":90},"acoustics-physics","Acoustic impedance is the resistance a medium offers to the flow of acoustic energy. It is the product of medium density and the local speed of sound and is measured in pascal-seconds per metre (Pa·s\u002Fm). When sound travels from one medium to another with different impedance, a fraction of the energy is reflected at the interface — the larger the mismatch, the more is reflected.","md",{},true,"\u002Fglossary\u002Facoustic-impedance",[126,127,128],"bell-horn","sound-pressure-level","attenuation-acoustic",{"title":130,"description":131},"Acoustic impedance — why bell horns work and reflections happen","Acoustic impedance is the resistance a medium offers to the flow of acoustic energy. Impedance mismatches between media reflect energy; matching is the reason sonic horns use an exponential bell.",[133],{"title":134,"url":135},"Wikipedia — Acoustic impedance","https:\u002F\u002Fen.wikipedia.org\u002Fwiki\u002FAcoustic_impedance","glossary\u002Facoustic-impedance","xFExTOR9WhiO7eNV4snAcnrWv7_X9LY4cNQD4dZdH2M",[139,290,482],{"id":140,"title":99,"aliases":141,"body":145,"category":270,"description":271,"extension":121,"meta":272,"navigation":123,"path":77,"relatedTerms":273,"seo":278,"sources":281,"stem":288,"term":99,"__hash__":289},"glossary\u002Fglossary\u002Fbell-horn.md",[142,143,144],"bell-shaped horn","exponential bell horn","exponential horn",{"type":52,"value":146,"toc":265},[147,166,170,186,190,240,242],[55,148,149,150,152,153,157,158,160,161,165],{},"A ",[58,151,78],{}," is the conical or exponential flare bolted to the driver of an industrial ",[70,154,156],{"href":155},"\u002Fglossary\u002Fsonic-horn","sonic horn",". Its job is to transform the high-impedance, small-area pressure pulse from the ",[70,159,73],{"href":72}," or ",[70,162,164],{"href":163},"\u002Fglossary\u002Fpiston-whistle-horn","piston-whistle"," into a lower-impedance, larger-area sound wave that couples efficiently into the gas inside the vessel.",[62,167,169],{"id":168},"why-the-geometry-matters","Why the geometry matters",[55,171,172,173,177,178,160,182,185],{},"The bell is not decorative. Its flare profile — usually exponential, sometimes catenoidal or tractrix — sets the horn's cut-off frequency: below the cut-off, the bell stops behaving as a horn and the radiated sound power collapses. A 60 Hz ",[70,174,176],{"href":175},"\u002Fglossary\u002Flow-frequency-acoustic-cleaner","low-frequency acoustic cleaner"," therefore needs a physically larger bell than a 230 Hz unit, which is why low-frequency horns are noticeably bulkier and heavier. Mounting orientation, flange standard (",[70,179,181],{"href":180},"\u002Fglossary\u002Fflange-standards-dn-ansi","DN",[70,183,184],{"href":180},"ANSI 150",") and the bell's projection distance into the vessel are all selected to match the cleaning target geometry.",[62,187,189],{"id":188},"materials","Materials",[92,191,192,207,216],{},[95,193,194,197,198,202,203],{},[58,195,196],{},"Carbon steel"," for ambient-temperature mounting on cool-side ducts, ",[70,199,201],{"href":200},"\u002Fglossary\u002Fsilo","silos"," and ",[70,204,206],{"href":205},"\u002Fglossary\u002Fhopper","hoppers",[95,208,209,215],{},[58,210,211],{},[70,212,214],{"href":213},"\u002Fglossary\u002Faisi-316-316l-stainless","316 stainless steel"," for corrosive or food-grade environments",[95,217,218,224,225,229,230,234,235,239],{},[58,219,220],{},[70,221,223],{"href":222},"\u002Fglossary\u002Finconel-625-718","Inconel 625 or 718"," for hot-side service above 350 °C, including ",[70,226,228],{"href":227},"\u002Fglossary\u002Fselective-catalytic-reduction","SCR reactors",", ",[70,231,233],{"href":232},"\u002Fglossary\u002Fair-heater","air heater"," penthouses and ",[70,236,238],{"href":237},"\u002Fglossary\u002Frecovery-boiler","recovery-boiler"," flue paths",[62,241,90],{"id":89},[92,243,244,249,254,259],{},[95,245,246],{},[70,247,248],{"href":155},"Sonic horn",[95,250,251],{},[70,252,253],{"href":72},"Diaphragm horn",[95,255,256],{},[70,257,258],{"href":163},"Piston-whistle horn",[95,260,261],{},[70,262,264],{"href":263},"\u002Fglossary\u002Facoustic-horn","Acoustic horn",{"title":113,"searchDepth":114,"depth":114,"links":266},[267,268,269],{"id":168,"depth":114,"text":169},{"id":188,"depth":114,"text":189},{"id":89,"depth":114,"text":90},"core-technology","A bell horn is the conical or exponential flare bolted to the driver of an industrial sonic horn. Its job is to transform the high-impedance, small-area pressure pulse from the diaphragm or piston-whistle into a lower-impedance, larger-area sound wave that couples efficiently into the gas inside the vessel.",{},[274,275,276,277],"sonic-horn","diaphragm-horn","piston-whistle-horn","acoustic-horn",{"title":279,"description":280},"Bell horn — definition, geometry and role in acoustic cleaning","A bell horn is the conical or exponential flare that amplifies and projects sound from an industrial sonic horn's driver into the vessel being cleaned.",[282,285],{"title":283,"url":284},"Wikipedia — Horn (acoustic)","https:\u002F\u002Fen.wikipedia.org\u002Fwiki\u002FHorn_(acoustic)",{"title":286,"url":287},"Power Magazine — The Theory and Application of Acoustic Cleaners","https:\u002F\u002Fwww.powermag.com\u002Fthe-theory-and-application-of-acoustic-cleaners\u002F","glossary\u002Fbell-horn","gKEabZrcxtpNiaEXB65PC50sPq3KHeDc-fyn9OvYp4I",{"id":291,"title":292,"aliases":293,"body":296,"category":119,"description":464,"extension":121,"meta":465,"navigation":123,"path":104,"relatedTerms":466,"seo":470,"sources":473,"stem":480,"term":105,"__hash__":481},"glossary\u002Fglossary\u002Fsound-pressure-level.md","Sound pressure level (SPL)",[294,295],"SPL","sound pressure level dB",{"type":52,"value":297,"toc":458},[298,315,319,395,399,412,416,433,435],[55,299,300,302,303,307,308,160,310,314],{},[58,301,292],{}," is the logarithmic measure of sound pressure relative to the 20 µPa human-hearing reference, expressed in ",[70,304,306],{"href":305},"\u002Fglossary\u002Fdecibel","decibels",". It is the primary specification figure for any ",[70,309,156],{"href":155},[70,311,313],{"href":312},"\u002Fglossary\u002Facoustic-cleaner","acoustic cleaner"," and the metric used to size noise-exposure controls at the work area.",[62,316,318],{"id":317},"industrial-reference-values","Industrial reference values",[320,321,322,335],"table",{},[323,324,325],"thead",{},[326,327,328,332],"tr",{},[329,330,331],"th",{},"SPL (dB)",[329,333,334],{},"Reference",[336,337,338,347,355,363,371,379,387],"tbody",{},[326,339,340,344],{},[341,342,343],"td",{},"0",[341,345,346],{},"Threshold of human hearing",[326,348,349,352],{},[341,350,351],{},"60",[341,353,354],{},"Normal conversation",[326,356,357,360],{},[341,358,359],{},"120",[341,361,362],{},"Threshold of pain",[326,364,365,368],{},[341,366,367],{},"140",[341,369,370],{},"Industrial sonic horn (lower-output models)",[326,372,373,376],{},[341,374,375],{},"160",[341,377,378],{},"Typical cement \u002F ESP sonic horn",[326,380,381,384],{},[341,382,383],{},"180",[341,385,386],{},"Upper limit of pneumatic industrial sonic horns",[326,388,389,392],{},[341,390,391],{},"194",[341,393,394],{},"Theoretical maximum for an undistorted sine wave in air",[62,396,398],{"id":397},"spl-and-cleaning-effectiveness","SPL and cleaning effectiveness",[55,400,401,402,406,407,411],{},"Cleaning energy scales with intensity, which doubles for every 3 dB rise. A 150 dB horn delivers roughly twice the energy of a 147 dB horn at the same distance. SPL is not, however, the only selection criterion: ",[70,403,405],{"href":404},"\u002Fglossary\u002Ffrequency","frequency"," determines ",[70,408,410],{"href":409},"\u002Fglossary\u002Fwavelength","wavelength"," and therefore penetration. A 150 dB low-frequency horn typically out-cleans a 160 dB high-frequency horn in a large open vessel.",[62,413,415],{"id":414},"spl-and-exposure","SPL and exposure",[55,417,418,419,423,424,202,428,432],{},"Reported nameplate SPL is measured at 1 m on the bell axis. Real exposure at the work area falls with distance per the ",[70,420,422],{"href":421},"\u002Fglossary\u002Finverse-square-law","inverse-square law"," and through enclosure attenuation. Compliance with ",[70,425,427],{"href":426},"\u002Fglossary\u002Fosha-29-cfr-1910-95","OSHA 29 CFR 1910.95",[70,429,431],{"href":430},"\u002Fglossary\u002Feu-directive-2003-10-ec","EU Directive 2003\u002F10\u002FEC"," is calculated from exposure, not from nameplate SPL.",[62,434,90],{"id":89},[92,436,437,442,447,453],{},[95,438,439],{},[70,440,441],{"href":305},"Decibel",[95,443,444],{},[70,445,446],{"href":404},"Frequency",[95,448,449],{},[70,450,452],{"href":451},"\u002Fglossary\u002Fsound-power-vs-sound-pressure","Sound power vs sound pressure",[95,454,455],{},[70,456,457],{"href":421},"Inverse-square law",{"title":113,"searchDepth":114,"depth":114,"links":459},[460,461,462,463],{"id":317,"depth":114,"text":318},{"id":397,"depth":114,"text":398},{"id":414,"depth":114,"text":415},{"id":89,"depth":114,"text":90},"Sound pressure level (SPL) is the logarithmic measure of sound pressure relative to the 20 µPa human-hearing reference, expressed in decibels. It is the primary specification figure for any sonic horn or acoustic cleaner and the metric used to size noise-exposure controls at the work area.",{},[467,405,468,469,274],"decibel","sound-power-vs-sound-pressure","inverse-square-law",{"title":471,"description":472},"Sound pressure level (SPL) — definition, industrial-cleaning ranges","SPL is the logarithmic measure of sound pressure in decibels relative to a 20 µPa reference. Industrial sonic horns operate at 140–180 dB SPL.",[474,477],{"title":475,"url":476},"Wikipedia — Sound pressure","https:\u002F\u002Fen.wikipedia.org\u002Fwiki\u002FSound_pressure",{"title":478,"url":479},"Acoustical Society of America — Sound Pressure Level","https:\u002F\u002Fasastandards.org\u002F","glossary\u002Fsound-pressure-level","ayEoQNuJweSv9WGpwDPcx5CMESsbiPd4QPUpIoyQA6M",{"id":483,"title":111,"aliases":484,"body":487,"category":119,"description":551,"extension":121,"meta":552,"navigation":123,"path":110,"relatedTerms":553,"seo":555,"sources":558,"stem":562,"term":111,"__hash__":563},"glossary\u002Fglossary\u002Fattenuation-acoustic.md",[485,486],"acoustic attenuation","sound attenuation",{"type":52,"value":488,"toc":546},[489,505,509,512,516,524,526],[55,490,491,494,495,497,498,500,501,504],{},[58,492,493],{},"Attenuation"," is the loss of acoustic energy as a sound wave propagates through a medium. It combines geometric spreading (the ",[70,496,422],{"href":421},") with absorption losses to viscosity, heat conduction and molecular relaxation. Attenuation rises sharply with ",[70,499,405],{"href":404},", which is the physical reason ",[70,502,503],{"href":175},"low-frequency acoustic cleaners"," reach further into large industrial vessels than their high-frequency counterparts.",[62,506,508],{"id":507},"implications-for-cleaning-reach","Implications for cleaning reach",[55,510,511],{},"A 60 Hz wave loses very little energy per metre of air travel; a 400 Hz wave loses substantially more. In hot flue gas the absolute losses change but the frequency dependence remains the same. The result is that a 60 Hz horn can clean fly-ash deposits 8–10 metres from the bell, while a 400 Hz horn is generally effective only within 3–4 metres at the same nameplate SPL.",[62,513,515],{"id":514},"implications-for-noise-control","Implications for noise control",[55,517,518,519,523],{},"The same physics that lets a low-frequency horn reach deep into a vessel also lets it travel further outside the vessel. Operator-station noise control is therefore harder for low-frequency installations, and ",[70,520,522],{"href":521},"\u002Fglossary\u002Fsound-attenuation-enclosure-sonic-horn","sound-attenuation enclosures"," are sometimes added at the bell.",[62,525,90],{"id":89},[92,527,528,533,537,541],{},[95,529,530],{},[70,531,532],{"href":409},"Wavelength",[95,534,535],{},[70,536,446],{"href":404},[95,538,539],{},[70,540,457],{"href":421},[95,542,543],{},[70,544,545],{"href":521},"Sound-attenuation enclosure (sonic horn)",{"title":113,"searchDepth":114,"depth":114,"links":547},[548,549,550],{"id":507,"depth":114,"text":508},{"id":514,"depth":114,"text":515},{"id":89,"depth":114,"text":90},"Attenuation is the loss of acoustic energy as a sound wave propagates through a medium. It combines geometric spreading (the inverse-square law) with absorption losses to viscosity, heat conduction and molecular relaxation. Attenuation rises sharply with frequency, which is the physical reason low-frequency acoustic cleaners reach further into large industrial vessels than their high-frequency counterparts.",{},[410,405,469,554],"sound-attenuation-enclosure-sonic-horn",{"title":556,"description":557},"Acoustic attenuation — why low-frequency sound travels further","Attenuation is the loss of acoustic energy as a sound wave propagates. Higher frequencies attenuate faster, which is why low-frequency sonic horns reach further in industrial vessels.",[559],{"title":560,"url":561},"Wikipedia — Acoustic attenuation","https:\u002F\u002Fen.wikipedia.org\u002Fwiki\u002FAcoustic_attenuation","glossary\u002Fattenuation-acoustic","WuKkiYEJRYbK7QdnPPy-tGtriMZpacuaLkpTV2w-RwM",1782613716034]