Because the economics of having large oxygen tanks aboard airliners simply doesn’t work out (not to mention that the air quality inside the plane would rapidly become unpleasant if fresh air wasn’t constantly supplied, regardless of the oxygen levels), commercial airplanes have a very clever system installed to solve the problem of ultra-low pressure atmosphere at cruising altitudes.
In most modern airliners (the Boeing 787 Dreamliner not withstanding), outside air is “bled off” from the compressor stage of the turbine engines and eventually piped into the passenger areas. However, a bit of processing is needed first as the compressed air is extremely hot (on the order of nearly 400 degrees Fahrenheit or 200 degrees Celsius) at this stage. Thus, before it enters the passenger compartment, it is first allowed to expand and is run through a heat exchanger and air cycle system to cool it off sufficiently. This system also can work as a heater, with some of the hot air mixed in with the cooled air to regulate cabin temperature.
Once cooled and filtered, the pressurized air, which now has sufficient oxygen density to keep people happily conscious, is piped into the cabin area, usually at levels around 12 psi (about equivalent to atmospheric pressure at 7,000 feet). Why 12 psi instead of something like sea-level pressures of about 14.7 psi? 12 psi is sufficient for the majority of passengers while simultaneously reducing the structural strain on the aircraft itself over something like sea level atmospheric pressures.
As for the air already in the cabin, this is vented out through an outflow valve (or multiple valves in larger aircraft), usually located near the rear of the plane. (FunNote: Before smoking was banned on commercial aircraft, the area around this outflow valve was generally stained dark brown from tobacco smoke.)
This outflow valve opens and closes automatically to maintain a steady pressure inside the cabin, while the entire system is ensuring that fresh air is continually being piped into and eventually blown out of the aircraft. In fact, while many complain of airplanes seeming “stuffy,” this system ensures that all the air in the aircraft is being completely replaced on average every 2-3 minutes. Yes, that means that your car, house or office is likely significantly more “stuffy” than a commercial airplane flying at 35,000 feet.
(Note: the Boeing 787 Dreamliner handles cabin pressurization a little differently, using a modernized version of the old, somewhat inefficient, electric compressor system seen on many older aircraft.)
Unfortunately, sometimes planes lose cabin pressure. Whatever the cause, the loss of pressure (usually set at atmospheric pressures past 14,000 ft) will result in oxygen masks deploying. From here, useful consciousness may only last as little as 5-15 seconds, depending on remaining cabin pressure, which is why it’s critical to immediately put your mask on, rather than helping someone else first. You can help them much better when you’re not unconscious or dead.
So how do these airline oxygen masks actually work? It turns out, the economics of having a centralized oxygen tank to provide even emergency oxygen for passengers likewise simply doesn’t add up. Similarly, having tiny individual pressurized oxygen tanks also isn’t feasible. In fact, these masks aren’t hooked up to any tank or air line at all. So how are you able to breathe oxygen through them?
While designs can vary slightly, in general, when you pull on the device to place it over your face, the tug on the mask’s lanyard releases a spring-loaded mechanism that sets off a small explosive charge. (Yep.) The resulting spark triggers a mixture of lead styphnate and tetracene to generate heat, which will eventually cause a chemical reaction that produces oxygen for your mask. (This is why they tell you to tug on the mask to get the oxygen flowing- you’ve got to set off the explosive charge to get the whole thing going.)
That’s right. What you breathe through the mask didn’t begin as pure oxygen. Rather, the plane is equipped with numerous small chemical oxygen generators (also known as “oxygen candles,” about the size of a small package of tennis balls) which contain a mixture of mostly sodium chlorate (NaClO3), less than 5% barium peroxide (BaO2) and less than 1% potassium perchlorate (KClO4). When these chemicals are heated by the lead styphnate and tetracene, each undergoes a reaction that ultimately results in a fair bit of filtered, life sustaining oxygen running through the tube to you.
Of course, you might also smell a faint burning odor, but this is nothing to be alarmed about; it just assures you that the system is working. In fact, if the plane is actually on fire, the masks usually won’t deploy, so as not to make the fire worse with the extra oxygen.
This brings us to the question of why the plastic bag on the breathing apparatus won’t necessarily inflate as you’re using the device. More than just cosmetic, the bags serve as something of a reservoir for oxygen. If you aren’t taking a breath at all (and have a good seal with the mask tight against your face) the bag keeps the precious, continuously flowing oxygen from escaping into the thin air around you, enabling more of the collected oxygen to be taken in when you do take a breath. When this is happening, or you are breathing out with the valves on the mask releasing much of the used air, the bag may begin to inflate as oxygen collects. When you breathe in, it will deflate.
So why won’t it always inflate at least a little to show its working? To begin with, you may not have a great seal with the mask on your face, particularly if you have facial hair. This will allow any produced oxygen (and air you exhale) to more readily escape. (As long as the mask is reasonably secure on your face, this should still provide you with sufficient oxygen to get by on as long as the plane isn’t flying above 40,000 feet and the pilot does his or her job and gets the plane down below 10,000 feet as rapidly as safely possible.)
Even if you have a good seal, however, the rate at which the oxygen is generated is often not enough to fully inflate the masks’ bag before you take deep, potentially panicky breaths, deflating it. This is simply because the oxygen generation isn’t on-demand (for the passengers anyway), but simply a continuous-flow production of oxygen.
Despite the potentially slow production, the chemical oxygen generators do provide oxygen at a sufficient rate to sustain passengers, generally designed such that peak oxygen production occurs right away (when the plane may be at very high altitude) with the oxygen production rates tailing off over the course of approximately 12-20 minutes before the system burns itself out.
This should be long enough for the pilots to get the plane low enough so that the air pressure is high enough for (relatively) normal atmospheric breathing. And if you’ve ever been lucky enough to be in this sort of situation, you know that those pilots can get the plane from altitudes like 35,000+ feet to safer atmospheric levels alarmingly quickly in an emergency; while it may not be literally true, it at least can seem like roller coasters have nothing on them, which is a good thing in this case.
- As a result of the way the system works for pressurizing the airplane cabin and keeping a steady supply of fresh air, the humidity levels are ultra-low, making it so you dehydrate very quickly on flights. Particularly for long flights, it’s critical then that you drink plenty of fluids. This ultra-low humidity level, combined with the low cabin pressure, also reduces your sense of taste and smell by as much as 30%, which is why airline food generally tastes so bland. To try to compensate for this somewhat, many airlines make sure their food is much more strongly flavored or spiced than you’d normally find appetizing.
Source…..www.today i found out.com
The Pakyong airport, finally puts Sikkim on India’s aviation map and is an example of stellar engineering.
If you’re flying to Sikkim, the nearest airport is at Bagdogra, in West Bengal, nearly 124 kms from the state capital, Gangtok.
The Pakyong airport now puts Sikkim on India’s aviation map. It is one of the five highest airports in the country and was built over several years, costing an estimated Rs 350 crore.
“The Pakyong (Gangtok) Airport at Sikkim got a license today for scheduled operations. It’s an engineering marvel at a height of more than 4,500 ft in a tough terrain. Will pave way for direct air connectivity to our lovely state of Sikkim, giving a boost to tourism & economic growth,” tweeted Civil Aviation Minister Suresh Prabhu.
Tourists, migrant workers and locals will soon fly on the low-cost airline SpiceJet, after it was granted permission to fly to Pakyong from Kolkata under the Centre’s regional connectivity scheme.
The picturesque runway of the Pakyong Airport in Sikkim. Image Credit: Soumen Mukherjee
1. The Pakyong airport in Sikkim is spread over 990 acres and is the first greenfield airport to be constructed in the north-east region of the country.
2. Over the years, several landslides near the runway resulted in work being suspended twice, but it was finally constructed and earlier this year, a fixed-wing 19-seater Dornier 228 IAF aircraft landed on the runway.
3. The airport is considered an engineering marvel because of its terrain. It is stationed at more than 4,500 feet and lies snugly between the Himalayas.
4. It is around 30 km from Sikkim’s state capital, Gangtok, and is located around 60 km away from the Indo-China border, giving it strategic importance. It is believed that the Indian Air Force (IAF) will be able to land various types of aircraft on the airport’s runway.
5. Until now, Sikkim was the only state in the country which did not have an airport. The Pakyong airport is the 100th functional airport in India.
According to MoneyControl, as per a previous proposal by the Ministry of Home Affairs, due to its “strategically important” location, the security of the Pakyong airport should be handled by the Central Industrial Security Force (CISF). The CISF is a professional aviation security force that handles 59 airports across the country.
The new airport will be an excellent opportunity for those of you who haven’t yet experienced this beautiful mountainous abode.
Source………Rayomand Engineer in http://www.the betterindia.com
Founded in 1943 by Swede Ingvar Kamprad and headquartered in the Netherlands, furniture giant IKEA makes revenue worth €38.3 billion with 411 outlets in 49 countries.
Deemed as the world’s largest furniture dealer, IKEA has finally set up it
s first-ever store on a 13-acre campus in HITEC city Hydearbad.
And while the numerous conversations CEO of IKEA India Juvencio Maeztu had with Indian biggies may be credited for the 2012 plan to finally take shape, there is a backstory many aren’t aware of. It’s how the 48-year-old bossman who relocated from London to Delhi’s NCR Region found a home away from home. All over a cup of masala chai.
It was 2012. Juvencio Maeztu had only arrived in India as the CEO of IKEA India. The switch from London to the bustling city of the National Capital Region was anything but easy.
Speaking to the Economic Times, the 48-year-old recalls, “I had many concerns. I am too small, and India is too big. Could I understand India, its size, its complexity and diversity? Will my European roots constrain me?”
His mind was clouded with doubts, but he had far more important matters to attend. For instance, his morning appointment at the FRRO (Foreigners Regional Registration Office) in Delhi. And he needed a passport-size photograph.
And so, his driver drove through the lanes of NCR, before making a halt at one of the many hole-in-the-wall photography studios. The one they stopped at was run by an old gentleman.
He just had to take a photograph and be on his way. How much time could it possibly take? He couldn’t be late for his appointment.
And so, the CEO entered the shop and asked the man, “Can you take my photo?”
“Yes,” came the reply.
“How long will it take?” Maeztu asked hesitantly
“Five minutes,” the man said.
The photo was clicked. But the wait for the 5 min – ‘N’ copies of the photograph dragged on for over 15 minutes. The printer was old and dusty, takes time to warm up, the man told him.
But he was quick to offer him – “Masala chai?” he asked.
“No” came the curt reply. Even as the man struggled with the printer, he kept persuading Maeztu to drink a cup of chai. An exasperated Maeztu gave him a brusque, “No”.
It was at this time that the photographer asked, “Sir, what’s the point of life if you cannot enjoy a masala chai for five minutes?”
“Something clicked,” Maetzu told the publication. He moved to take a seat, drank the cup of masala chai. The appointment was forgotten, and the two men chatted for over an hour that day.
He may have missed his FRRO appointment, but Maetzu says, “That was the moment I connected with India. It was a turning point.”
He had finally found a home away from home.
After a long wait of six years, IKEA has now made its debut in India.
While land has been acquired in Gurugram, Bengaluru and Mumbai, the retail stores will only come up in the next few years. With a staff strength of 535 and an investment of Rs 10,500 crore, the furniture giant is here to make it big reported the publication. The current number of employees though is estimated to be around 950 people directly, about 1500 at its store in Hyderabad and aims to hire another 15,000 employees as it expands its operations.
“We are here for the long term. We think of 100 years when we think of our strategy. I have taken no shortcuts. More importantly, I have had no pressure (from the headquarters) to take shortcuts. In the next 100 years, the sheer size of India makes it important. There are other super big reasons. India is challenging us to find better ways to do business. This is a market you need to learn and not come into with an attitude that you know everything,” he said.
The vision is to also have over 25 stores and 20,000 employees in India by 2030.
The report adds how India is the first market where IKEA is rolling out a multi-channel retail online and offline strategy from day one. It is also planning to explore the use of eco-friendly raw materials like bamboo, coconut waste, water hyacinth and recycled PET.
Apart from working with over 80,000 farmers to boost cotton production, it is also helping skill 1,200 women artisans with the UNDP under its programme ‘Disha’ and boost employment from underprivileged communities.