In 1888 , Theophilus van Kannel patent the revolving threshold , an invention he claim would preclude " noxious effluvia " and " forbidding miasma " from entering a building when someone like the postman came and went [ root : Guardian.co.uk ] . handily , the revolving door also eliminated the need for one person to hold a door open for another ( legend has it that Van Kannel had grown tired of opening doors for his traditionally - disposed married woman ) .
But the revolving door was n’t the only thing van Kannel invented for the purpose of keeping cold atmosphere and pollutants out of buildings . His sophomore inventing effort was the air curtain , which he patented in 1904 and which was finally installed for the first time in a construction in 1916 [ source : Miniveil.com ] . To put it just , an air mantle is a continuous stream of air gasconade from the top to the bottom of an opened doorway . normally used as a 2d line of defense inside a closed doorway or to put back hanging charge card flapping in an heart-to-heart doorway , air curtains form a roadblock that citizenry and products can flow across , but atmosphere ca n’t . This means that the climate on one side of the air curtain does n’t agitate hands with the clime on the other .
The breeze curtain does two matter : First , it insulate , and we all cognize theinsulating power of air . It ’s the stratum of atmosphere trapped between double - pane windows that preserve heat from move across them . ( What ? Did you opine it was the doubled thickness of the field glass ? ) second , an air curtain used as backup inside a door can be angled to blow outside air back out from whence it add up .
Though an invisible drape of air may sound like aStar Trekapproach to Enterprise efficiency , if installed and used correctly , an air travel pall can increase energy efficiency and keep pollutant and insects out of an capable threshold .
Air Curtain Mechanics
There are two shipway to use an air pall . you could utilize it in an opened doorway , in which case a stream of air runs endlessly . You ’ve probably felt the ottoman of air from this type of air curtain when you ’ve entered a heavy - box , storage warehouse - style depot . Or , you could use the air travel curtain as a second line of defense behind a closed door , in which guinea pig the aviation curtain is activated only when the door opens . It springs into action , blasting air for a couple s until the door is again closed .
In both cases , the drape is mounted on the heated / airwave - conditioned side of the doorway , run across the length of the door opening . Its intake sucks in conditioned air and blasts that tune either straight down or at a slightly outward - tilted slant ( see more on next page ) to push away any outside air that otherwise would go into through the doorway .
An air pall can be augment with an electric fastball . Imagine walking into a building on a freeze winter mean solar day to feel a cascade of heated up air . And speak of warmth , because hot melody be given to pool by the baulk , an air pall also help re - diffuse that heated air . The current of air is also impregnable enough tofend off flee louse , dust , befoulment and any other unwanted contaminants [ reservoir : AirDistributors.com ] . In fact , some businesses expend melodic line curtains for the determination of keeping airborne contaminants from hook into sterile spaces . And curtains can even be used to guard clear oven and Deepfreeze .
The Physics of Air Curtains
Imagine rolling two testicle at each other for a head - on collision . After they collide with , which style they roll depend on asimple constabulary of physics : F = MV2 , or " force equals peck times velocity ( square up ) . " This means that a low formal rolling fast can potentially overpower a large ball rolling slowly .
The same concept run short for the gentle wind drapery . The force of the air blowing from the pall has to be stiff enough to overwhelm and turn back the force of the air coming from the outside . If your giant , open storage warehouse door is constantly getting pummel by strong winds , you ’ll call for a sinewy air curtain – one that blows a lot of air with great velocity .
The other thing to take into account is the direction of that velocity . You might think that an air mantle would most efficaciously fight horizontal winds with its own horizontal wind . But that ’s not really the case . When atmosphere is blow directly out the doorway for a psyche - on hit with other air ( like those two Ball we advert above ) , much of the power of the air is lost over distance . Instead , air curtains direct their flow of air mostly downward toward the floor of the door . The system must blow firmly enough to insure the air is still jaunt at the require speed as it reaches the bottom of the threshold , and that the speed is also stronger than the speed of the outside , inrushing air . As such , the curtain represent like a rampart that external air comes toward and then bounces off of .
To give you an example : If wind were blowing horizontally toward the room access at 20 feet per second ( 13.6 mph/21.2 kph ) , an air curtain angled outward at 15 degrees would have to spoil 133 animal foot per second ( 91 mph/146.4 kph ) to counteract the force of the outside aura .
All of this imply that you ’ll need to play with your air drape to get its forcefulness just flop – at just the right hurrying and angle to most efficiently counteract the effect of the inrushing gentle wind . you’re able to fine-tune your air drape three ways : Either crank up the volume of air blown , the hurrying of the air blown , or direct this speed outward a bit , normally at an slant of between 10 and 20 degrees [ source : PoweredAire.com ] .
The Cost/Benefit of Air Curtains
Like many economic interrogation , the one of air curtain toll - welfare depend on a issue of variables . A small , unheated 36 - inch ( 91.4 - centimeter ) melodic line curtain can cost as picayune as $ 200 [ origin : Amazon ] . On the other hand , a high speed , heated curtain for a 9 - foot by 14 - foot ( 2.7 - meter by 4.2 - meter ) door can run almost $ 450 [ root : Grainger.com ] . So , just like tilting and power your air drape to do what ’s require and no more , the first fast one in air curtain economics is to pay for only what you need . The sizing should be a no - brainer : Measure your door . Next , resolve if comfort or efficiency is your end end – if it ’s ease , go heated ; if not , consider an unheated modelling . Finally , estimate the force-out your air pall will need to counteract the military group of external air travel . For example , if you ’re fighting a windy Minnesota winter , you ’ll need more airwave at a higher amphetamine than you ’d demand in an field with a milder mood and no wind .
The other welfare of atmosphere mantle is that they can help a structure make Energy and Atmosphere points , Indoor Air Quality point , Innovation in Design degree , and Indoor Environmental Quality point , all of which add up to theLeadership in Energy and Environmental Design ( LEED ) certification[source : Air Conditioning , Heating and Refrigeration News ] .
If you need to make out your vigour savings beyond the initial expenditure , you ’ll have to take into account thing like steer speed and vitality costs . Berner Internationaland Mars Air Systems , suppliers of air curtain , let in calculator on their sites that can help estimate the monetary value and rescue of breeze curtain over time . For example , an atmosphere doorway that costs $ 3,000 , set up on an 8 - foot by 6 - foot ( 2.4 - meter by 1.8 - meter ) threshold with an modal out-of-door temperature of 50 degree Fahrenheit ( 10 degrees Celsius ) and nothingness speed of 8 mile per hour ( 12.8 kilometers per hr ) will pay for itself in almost exactly a year .
I admit it : I ’d never get word of an air curtain before write this article . But now that my consciousness is raise , I see them everywhere . " Oh , is that what that blow of live airwave is every fourth dimension I walk inside the local supermarket ? " I think . And there ’s another at the dentist ’s function . It turn out there ’s been a silent revolution in entrance gasket engineering science going on all around us , every day , unnoticed . Join the revolution or be left in the cold , inefficient dust .
