What is Air Lock? 

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This may be the only RU-vid channel that answers the question brought up in the video title during the first few lines. No clickbait nonsense, no long-dragging filler talk just to make the video longer. Just simple, straightforward and straight to the point explanations. Keep up the good work!

Another form of air lock is very deadly. An air emboli is when a bubble of air manage to enter your blood vessels and can block it leading to that organ not able to get blood and can prove fatal indeed.

Grady: A civil engineer who frequently discusses the strengths and limits of materials within specific design parameters and expected uses. Also Grady at 8:47: scrapes a metal spoon around the inside of a teflon-coated pot.

I have to say, I love how you deal with sponsors. I appreciate it so much that I often end up watching the full sponsor add at the end of the video. It is really irritating when you’re watching another channel, and mid sentence, a commercial interrupts what I was trying to learn about. In those cases, I completely ignore the commercial and focus on the timer counting down to when I can skip the commercial. Thanks again, and I love the content.

This channel inspired me to become a student of Civil Engineering, never thought I'd be interested in sewage and drainage and other public infrastructure. Thanks dude!

this was absolutely the most overlooked and frustrating yet easily avoidable problem that I dealt with when commissioning new wastewater facilities over the last decade. not only was this a problem in itself, but it effected system monitoring instruments and almost always set off alarms that indicated a different problem. I lost so many nights of sleep over "critical alarms" that amounted to "just air in the pipe"

I was recently hired as a Process Operator for what will eventually be a Polypropylene plant. Having no experience in the industry previously, it amazed me to see the amount of trapped air that exist in our large 24" cooling water lines (when we filled them up we opened vents on top). Vapor lock in general has been a difficult concept for me, and your video was the first to answer and demonstrate it visually in a way that is easy to understand. Thanks a bunch!

As a project manager for a mechanical contractor this concept is so important when flushing and filling any building’s piping system. Awesome video.

the eyeballs are distracting i just want to watch the flow but the flow is watching me back

I’m graduating with a civil engineering degree in May! With an emphasis in water resource. I’m going to work at a firm that specializes in large scale irrigation systems, continuous acting air vents are a necessity in these large diameter pipelines! I love seeing the backyard experiments to better visualize what’s happening in the pipe. Love the videos thanks for all you do!!

The avergae view-time-to-length-of-video ratio on Practical Engineering must be through the roof. All videos are so concise and engaging.

God you are such a good writer. I’m a sophomore in biomedical engineering and your videos are such a fun buffer from my coursework to allow me to step back and appreciate the industry as a whole. I love your topics, but your scripts are just amazing. Keep it up!

I work in wastewater treatment, and airlock is one of the more vexxing problems we have to deal with. It is unbelievablely frustrating to tear down and rebuild a large pump only to find that it still is not pumping enough, or not at all, then realize the air relief valve is simply plugged.

Air Lock is Rayquaza's ability that negates the effects of weather.

Not only did I learn from this video, I also enjoyed the way it was explained and presented. Enjoyed it, thanks.

Practical Engineering : "Don't do it, don't do it..." Brain : "Put googly eyes on it"

As someone who works as a engineer at an valve manufacturer who makes air valves, I really appreciate this video. I can now share this video to help explain to people why someone would even need something my company makes.

You're one of the channels I'm most excited about when they release something new, maybe because you don't release new content that often. But boy do I know I'm in for a few minutes of some of the best content on RU-vid...

This analysis is exactly right, but in my experience designing pipelines, it was not commonly understood by other engineers. I figured it out myself and used it in designing several pressure pipes (force mains) carrying sewage, and in many cases these had high points where gas from the sewage could accumulate. The problem there was that (1) a gas release valve at the high point could quickly become fouled with scum from the sewage, and (2) these high points were often in locations that were not practical to access for maintenance. So, I often designed the pumps to discharge against the added pressure created by air in descending legs of the pipe (referred to here as "waterfalls"). That required more electrical energy for pumping, but worked reliably with little maintenance, which is an example of trade-offs that are inherent in good engineering design.

As a boiler tech I “knew” all this stuff but the clear tube visualization really helps put knowledge to practice. Thanks!

Ah, the dreaded vapor lock that can occur on normally aspirated IC engines! I had an older Toyota Corolla that would get vapor locked in hot weather. The problem was eventually traced to the fuel line where the previous owner had replaced a section it. They had routed it too close to the exhaust manifold and in hot weather, fuel would be vaporised in the line and block the flow of liquid gas to the carburetor.

Thanks a lot, i’m a med student and i found your videos really helpful for understanding some topics that have engineering aspects. such as water hammer effect in conditions of hyperdynamic circulation e.g. anemia and aortic regurgitation, and how an air embolus forms a vapor lock. Thanks again sir for producing awesome scientific content.

Thank you for making all of the content that you create. It's opened my eyes to the world around me quite a bit more and I feel empowered to continue to learn how everything works, even if I will never achieve that goal I will continue with that mindset!

“Engineering nearly always involves assumptions and simplifications” My immediate thought: Pi=3=e

I've dealt with this on a project I worked on where we were bypassing a city's main water treatment facility. Obviously getting the water from the river wasn't an issue as we had submersibles feeding a set of high-head power units but the end point of the very long pipe run had to go over a 25' high wall to feed fresh water into their system. Basically looked like the trap under your sink but upside down. Because of this, when we first fired up the system, it was deadheading hard until we figured out that we needed to place air vents/valves at a couple places along the run. I think it took like 3 or four vents per discharge pipe along the path to get it to actually work as intended. If course we did the whole project in winter. Which meant we were sliding around in mud for several months. Fun times.

More teachers should show your videos in class for related topics. I’m positive people would be more motivated to learn thanks to good quality content like yours.

He always looks like he's just about to burst out laughing. It's contagious

Sufficient pump head and flow is especially important in U-tube (not RU-vid) heat exchangers. These are commonly found in nuclear power plant steam generators and even in some electrical generator coolers and various process boilers. You can't put a bleed valve on every tube so you always have to evaluate how much head you need to drive non-condensable vapors from the tubing.

Grady: "Air gets trapped where it's not supposed to all the time." Me: "hhhehehe" Grady: "hhhehehe" Me: :o

I never took engineering at or after leaving school. However you and a few other channels have truly opened up a passion in these ways of thinking about/solving life's problems and I just wanted to say thank you for unlocking another interest from within me ::)

I love how straightforward engineers are. Makes for very good and informative videos.

Let's have a moment of silence in remembrance of all the legions of luckless engineers who found out those well-known facts the hard way so we can make succeeding look easy.

It's entertaining to me the differences and similarities in our industries. I do mechanical and plumbing design for buildings and we always go the way of sizing the pumps larger, even for some rather big runs of piping. We do try and remove the air for open loop water systems but those are rather easily naturally vented. And the principles of flow with sir present are accounted for with drainage piping in building codes by having them oversized. I work with civil engineers and it seems somtimes we use different principles to handle the same problems before and after the pipes leave the building

I am a medical student, yet this videos are fascinating. I could had died without knowing whatwas an airlock, without having a change in my life, yet the complexity of this simple, yet invisible problems for anyone that is not directly involved in the engineering field, and how ingenious we are to overcome this problems is fascinating. Thanks!

Grady does an excellent job explaining and answering the questions brought up. He makes me feel like I am also an engineer because I understand what he says when. But of course it’s because of how intelligent he is that makes it sound easy and simply. I enjoy these videos.

Another big problem you should mention is that of corrosion. Air or vapour locks in pipework can readily create an interface environment where the contents become corrosive where the pipe would be otherwise unharmed by being full of the same product. This can be a common and expensive problem where the products are acid, correctly selected grades of stainless are very resistant to strong acids but in the vapour space there is more likely to be a weak, humid acidic atmosphere which will damage the surface far more readily than the strong acid itself.

7:26 I recognise this system! In reverse, it's also what lets a toilet know when to stop filling a tank - when the water level gets high enough, the float stops a valve which means no more water.

My Dad would have loved your videos, if RU-vid had been around while he was. He was a mechanical engineer for Ford specializing in heating and cooling systems. A brilliant man who had a gift for explaining complex systems in a simple and accessible way, just like you. Thank you.

Great info and love the clear pipes for the visual. I've been in the fire suppression industry for a long time and have had some fancy titles yet I ALWAYS learn something when watching your vids on piping. Very well done sir, thank you

The liquid in a pipe can also boil depending on many factors, heat being one of them. Many that drive or have driven older cars know about 'vapor lock'

This is the most interesting video I've watched in a while. I loved the opening, about our assumptions and simplifications. I never thought about air acting as a kink in the line, and I very much appreciate being able to see it in action through the transparent pipes.

Love your teaching technique. You explained this concept better in 10 minutes than I ever got in 6 years of undergrad and graduate school.

If only the teachers would have shown us this kind of examples in the 70's.... would have made the topic so much more understandable.

Once I land a job after graduation, Practical Engineering is the first channel I'm supporting through Patreon. Thank you for all your hard work!

Another way of having "air lock" is when there are different metals involved or different electric potentials on both ends of a pipe. Dissociation of the water mollecule to hydrogen and oxygen is common in these conditions. Exploding "air" from the bleeder is deffinitely interesting!

“I’m an engineer not a chef” That sounds like a line from a movie.

Im a mechanic (auto) and its amazing to me that most people don't realize that air needs to be manually released from an engines cooling system almost every time it is serviced ( flushed radiators, change thermostats, hoses etc) in order to remove air pockets, some vehicles have to be jacked up on one side or the other in order for the air pocket to escape but most have bleeder valves built into the system. This problem didn't really come about until the late 80s when everything was made more compact under the hood causing the cylinder heads to be higher than the vehicles radiator. Thanks for the video's and keep up the good work! Its never too late for old guys like me to learn how things work 😁

Back when you first did the “what’s that infrastructure” series I sent you a photo of a 5 meter vertical pipe that comes directly out of the ground in my local park. Our suburb was once a swamp and I assumed that there was probably some gasses that somehow needed to vent from somewhere underground, but now I think I would probably guess it was one of these airlock valves. And I think I remember seeing sewage department signs near by to this pipe so I guess methane and other nasties could contribute to this airlock problem. One weird thing though: why the height? The suburb was fairly flat and this was probably already at about the highest spot in the area, so maybe just to prevent tampering, or to allow nasty smells to dissipate before they fall to pedestrians nose height or something like that.

I love these uncommon problems. I watch a lot of science/engineering type videos and your channel always surprises me with something I'd never considered. Thanks!

I was having this problem last night with my home plumbing. Having watched your video, I understood the problem and was able to take actions to correct it myself. Thanks for the great video!

Wow, the clarity of the content and the comprehensive coverage of the subject is amazing. Subscribed!

I'm graduating in May with a Civil Engineering degree and I truly believe your videos will help me be a better engineer. If anything, it's good I'm being exposed to concepts I otherwise wouldn't have been taught, but your demonstrations are ALWAYS super clear and on-point.

5:45 - What a coincidence: A few days ago, I removed an unwanted U-bend of my washing machine’s drain hose that often lead to suds locks during spinning laundry. And now the reason for that phenomenon - reduced water flow due to air lock - is given in this video! ;-)

I'm a maintenance fitter on a 200 km water pipeline with over 450 air valves and this explains beautifully what happens inside. I wish I was shown this when I was an apprentice.

Really good job. When studying for the PE (Thermal Fluids), I never got the gradient line concept but your explanation was so clear.

Another form of Vaporlock I've experienced is in automotive applications. The heat from the engine vaporizes the fuel in the fuel line creating an Air Lock and either preventing the vehicle from starting or causing it to have a tough time starting. Most of this is experienced with carbureted vehicles that use an engine mounted fuel pump. Those normally only use a small amount of PSI so it isn't able to overcome the air lock.

Bro, the eyes on your translucent tube setup are super cool. Also, this is another fantastic video

I work in the valve industry and would love to see more of these types of videos, keep it up!

As an industrial mechanic, I love your channel and end up watching your content into the wee hours of the night, thank you Grady

Nice vid! Im in the HVAC industry, but recap never hurts 👍 Side note: some fluids tend to clog up automatic air vents so closing valve before it is handy for maintenance

*I love how you're teaching me things i didn't even know they were a problem until you said it xD*

as a mechanical engineer, i care about air lock. but i find it really satisfying that in order to simulate it, you just had to put the pipes together without consideration for it. easy experiment!

Your unabashed enthusiasm for engineering makes watching all your videos sooo much fun. Your models bring me back to childhood. You should be running a learning museum like the Exploratorium used to be! Thank you. Also, I feel like there should be a wall of science built where you connect all your hydrodynamic tube example systems together and it just gets a continuous feed of water (the steam generation part might be tricky but that can be worked out later) and it shows all the systems and problems at once!

Hey Grady, could you do a video about how giant industrial chemical processing plants work? Whenever I pass by a huge industrial complex or a gas refinery, I'm always blown away by the huge complexity of the infrastructure. The massive web of piping literally overwhelms me and I can't even begin to conceive how people manage to design such things! 😊

I remember living in a 1960-s Soviet mass-production 5-floor house. Living on the top floor, every time when central heating season started, we had to bleed our radiators using manual valves.

This is my first video of yours that I watched and I love your format and the explanation for this particular subject was easy to follow and spot on! Subscribed! Thanks and I look forward to more content from you!

This thing I learnt in my engineering really helped me out. Our old building never had air release value and in summer water used to be irregular which means water is drained. So I just opened all taps if water drained in OH tank

I always look forward to your videos. You always have an interesting topic and present it in such a way as to be understandable by even us simple minded ones! Thank you!

Air and vapour locks can also affect fuel delivery in vehicles, especially with fuel like gasoline where its own vapours can lock up a line. In the German V2 rocket program, air or vapour lock interrupting or blocking fuel flow in their prototype liquid engines resulted in many catastrophic and explosive failures up until it was addressed.

Great video. I learned this quite viscerally in the first winter in my home. In fixing my hydronic heating system, the 2nd floor zone ended up as one big air lock bubble with no bleed valves upstairs. I had to do some plumbing to add a valve to effectively flush out the bubble!

Brilliant explanation and demonstration. Seeing the phenomenon in action makes all the difference in understanding things intuitively.

I live that your wife helps you with the Sponsor ads lol

An airlock is where you have 2 or more doors that need to be opened to enter your base

Im a plumber, and I know a lot of us like to talk bad about engineers, but quite a few of your videos on water and plumbing are so very useful. I didnt even know about a trompe, and using some of your videos I was able to explain to my apprentices why we have to do things the way we do even though code might not demand it.

Who gives an awesome video like this a thumbs down? 🤔 Thanks so much for sharing. Your videos are so much fun and educational!

Liking for the googly eyes (and the well explained educational video)

I work in a coal power plant. Just last night I had to clear a vapor locked line that goes into the boiler. The pressure of those lines is 2500psi. Burping those lines is always stressful. Hope the packing holds on the block valves. I am going to show this video to the guys at work.

That explains why I had to make sure my vinyl tubing water level had to have NO trapped air. Thank you for your great videos Practical Engineering!

That visualization with the pipes and colored fluid was super helpful in understanding why air gets trapped in automotive cooling systems

1:40 Is that Dr. B?! Gotta love that HEB!

Hi Grady! I love your videos and have a new video suggestion; Drain vents! I would love to understand why drain vents are required in different circumstances and how they work/help with fluid flow in drain pipes! I am sure that you are up for the challenge, and will make a great video to help people to understand :) Keep up the good work!

Great video and epic final. Greentings from Venezuela.

I have been after this topic for a long time unable to understand the depth of problem associated with it. Now I can really see it with my naked eye. Thanks a lot for the video...!!!!

I love your channel, and I am also really concerned with your teflon pan. I mean, you could believe a company like DuPont if you want, but I've chosen to throw those tetrafluoride horrors out. People used to laugh at those who believed that cigarettes were carcinogens, too. 'Nuff said. Keep up the good work on the videos (love'm!), and stay safe!

I would like to see the airlock at 5:42 in a physical model. My understanding is that flow would not stop permanently but only long enough for the trapped air to return to the local highest point in the pipe. I feel clarifying would be nice because I feel the video makes it seem like the flow will stop and not restart and I do not expect this to be the case.

testing and balancing apprentice here, these videos are very useful for explaining phenomena that is seen in the field, you the man.

Wonderful video Grady !

This guy is a real triple threat. Got the looks, the smarts, and the youtube fame and fortune. 😂

The googly eyes helped me stay focused on the pipe haha googly eyes

I love your work. You make learning fun. Keep up the good work !!

my wife and I just had our first hello fresh meal gifted to us from a friend; I'm a chef so I've always been hesitant, and I'll put it fully out there; I don't like the excessive packaging, the quality of the food was good but not incredible, but it was nice to not have to shop, not have to meal plan, and not have to figure out how to use up the excess ingredients; and my wife could help easily because I didn't have to tell her how to help, she just followed the recipe card. and if you're used to cooking, you can easily tweak the meals to your liking.

Can you just use an open stand pipe with the top above the hydraulic grade line? (I mean assuming that you don' t mind venting the vapors involved, of course.)

I love all the content you talk about in this channel. You inspired me to start my own channel. I would love some feedback/support. Keep up the great videos you present here.

Very useful man. I saw some man use a plastic bottle to lock the air behind the valve. and you can see it works very well. Water completly full of the tube . Make water flow very strong.

I love your videos. You always teach me something new and very interesting.

Decompression sickness, aka the bends. Is basically air locks inside your blood vessels.

Just when I was out of youtube video in my subscription list to watch during my lunch, perfect timing Practical Engineering !

You just made a set up for a video on cavitation corrosion from air and rough flow areas. Excellent content and format. Thanks!

I work in the Well and Water Treatment business we get this sometimes when rebedding and changing filters, air locks restrict pressure to the house and is a pain to get the air out, very interesting and helpful video