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Here's information on the simplest type of air valve; the 2/2 style.

The first 2 in the 2/2 air valve refers to the number of "working" air ports that are found in the valve body. That is, the number of ports that supply air to the valve, and channel the compressed air to whatever it is that the valve is supposed to do.

Most 2/2 valves will have numbers or letters etched, cast or painted near each of their two "working" air ports. If there are numbers near the ports, the number 1 would be the supply port to bring the compressed air to that valve. Port number 2 would be the working port from which air would flow to accomplish whatever task that you wanted that valve to do.

If the port designations are letters, then port 'A' would be the supply port and port 'B' the working port.

If the 2/2 valve is to be "air operated", that is an external air signal is to be used to shift the 2/2 valve, there will be another port. That port may not have a designation or it might say '12'. No, that's not a twelve, but rather indicates that air will flow from port 1 to port 2 when an external air signal operates that valve.

The second 2 in a 2/2 air valve indicates the number of positions that the internal valve mechanism has. In this case, two. When this valve is operated or actuated, it will either open or close. At rest, that is when the external valve operator has not been activated, the internal valve mechanism will either stay open or closed.

Most 2/2 compressed air valves are classified as NC. NC stands for normally closed. This means that when the valve is not actuated, it's normal state is closed, and compressed air cannot pass through it.

There are some applications for 2/2 valves where the flow of air through the valve when it is not being operated is desirous. A NO or normally open valve would then be selected. When this type of 2/2 valve is at rest, compressed air will flow through it, and it is only when the valve is actuated that the flow of air will stop.

All 2/2 valves will have actuators that will operate or 'shift' the air valve.

A compressed air blow gun is a good example. On it there will be a push button or a trigger of some kind. When the button is depressed or the trigger is pulled, the compressed air will flow through the gun and out the nozzle to atmosphere. When the actuator is released, an internal spring (a secondary actuator) will shift the internal valve mechanism back, and the air will stop flowing. A compressed air blow gun contains a 2/2 NC air valve.

Some other 2/2 valve actuators are whisker switches, toggles, push buttons, palm buttons, roller cams, electric solenoids or compressed air.

2/2 valves can have detented or non-detented actuators. If the actuator is detented, this means that when the operator actuates the valve, the actuator will stay in the position selected until it is again moved by the operator. Toggle switches for air valves are often detented. You flick the toggle in one direction to actuate the valve, and it will stay actuated until you move the toggle back. The detented 2/2 valve may not have an internal spring, though with standardization of manufacture, even a detented valve may have a spring, since various kinds of actuators may be affixed to that same valve body.

Non-detented valves do contain an actuator spring, and the internal valve mechanism will "spring" back to the other position when the operator releases the primary actuator, similar to what happens when the button on a compressed air gun is released.

At ABOUT-air-compressors.com, an e-book entitled All About Air Valves - volume one - will soon be available (end August 06). If you are interested in more information about air valves, do visit the site and download a copy.

All 2/2 valves must, when operated, allow air to ultimately flow to atmosphere. If a 2/2 valve is selected to provide air to a closed tank or air vessel, then when the 2/2 valve is shifted to a closed position, the air will be trapped in the downstream line. You wouldn't select a 2/2 valve to provide compressed air to an air actuator, for example.

The exception to this rule are inflatable bladders that contain their own integral 2/2 valves; a bicycle or vehicle tire being good examples. When you connect your 2/2 air supply valve to the tire valve, the tire valve - itself a small 2/2 valve - is actuated by the supply valve fitting, allowing compressed air to flow into the tire. When the supply valve is no longer actuated, as long as the fill fittings is attached to the tire valve, the line is pressurized. That's why, when you pull the fill fitting away from the tire, you hear that characteristic "pssssst" as the air that's been trapped between the two valves is vented. The tire valve will have shifted back to being closed by the air pressure inside the tire, thus preventing the compressed air in the tire from escaping back to atmosphere.

Other 2/2 compressed air valves commonly encountered are those push button valves on the handle of air tools, and the air-horns that are commonly heard at sporting events.

The air-horns were designed as distress sirens for small boat operators. The push button on the top of the gas canister is the 2/2 valve, and it's the pressure of the compressed gas trapped in the canister that forces the valve shut (NC - normally closed) when the button is released.

I guess it's better to hear an air horn at a football game than indicating some poor boater's distress out on the lake; unless it's blasting into your ear, of course!

And as always, if you have any questions, please send me a message from the contact screen at my web site.

Bill Wade's experience in compressed air and other industries spans decades; from field sales positions through to the corporate presidential office. His sales agency represents a select group of industrial firms. Mr. Wade writes about all facets of compressed air at http://www.about-air-compressors.com

Do You Have Flimsy Nostrils?

One of the most common reasons for continued nasal congestion despite allergy medications and even nasal surgery is due to flimsy nostrils. Your nose comes in various shapes and sizes, but having naturally thin nostrils or weakened nostrils after rhinoplasty can lead to flimsy nostrils that collapse during even quiet inspiration.

Unfortunately, many people undergo a number of different medical treatments using allergy sprays or even surgery before this condition is even considered.

There are three simple ways to tell if you have flimsy nostrils:

1. look in the mirror and take in a deep breath through your nose. Do the sidewalls of your nostrils cave in as you breathe in?

2. place your index finger just beside your nostrils on both sides. While pushing gently on each side, pull the cheek skin up and away from the nose, towards the outer corners of the eyes. Breathe in and see how you feel.

3. take off the cotton ends from two Q-Tips and place the thin end inside your nostril and lift up and sideways. Take a deep breathe in. Is your breathing much improved?

One very important point to make here is that how stuffy your nose is on the inside can also determine how much your nostrils will collapse. Think of sucking through a flimsy straw. If you pinch the middle slowly, the end will collapse since there's increased airflow. The same thing happens with your nostrils. In many cases properly addressing intranasal allergies or a deviated septum and enlarged turbinates will prevent the nostrils from collapsing.

If you use over-the-counter decongestants like Afrin or Sudafed and you can breathe much better, then you need to address the inside of your nose first. But if you still have nasal congestion and it's obvious that your nostrils are caving in, then you have flimsy nostrils, or nasal valve collapse. Lifting up your nostrils by pulling your cheeks apart or using Q-Tips is a good test to see if you have this condition.

If treating your allergies or deviated septum or enlarged turbinates don't help, then there are two major ways of treating this problem:

1. Nasal dilator devices.

These come in two varieties: external and internal.

External devices are mainly over-the-counter adhesive strips that attach to the nostrils on the outside that pulls the nostrils apart. This works for most people, but for some people with thick or oily skin, it may not work as well.

Internal nasal dilator clips. There are a number of these devices, including Nozovent, Sinus Cones, Breathewitheez, and Brez. You can find any of these devices online.

2. Surgery

The most common way of managing this surgically is through a functional nasal reconstruction procedure, using rhinoplasty techniques. Small strips of cartilage (harvested from either the nasal septum or the ear) are placed under the skin of the nostrils and between the septum and the cartilage of the lower part of the nose. There can be a little widening of your nose due to added support structures.

A newer and easier way of addressing flimsy nostrils is to make a tiny incision under the lower eyelid and attach a thin suture the bone. The suture is then threaded under the skin towards the floppy nostril area, looped about the nostril, and tunneled back out of the eyelid incision, and tied under a mild degree of tension. This suspends the nostril so that it doesn't fall in. This procedure can be performed under local anesthesia and it literally can take about 30 minutes and recovery is very quick. Unlike the more formal procedure, your nose is less likely to widen, since you're only suspending or "hanging" your nostrils to the bone above.

About the Author

The above article is an excerpt from my E-Book, Un-Stuffing Your Stuffy Nose. Download for FREE by clicking here: http://tinyurl.com/23dgf38. Steven Y. Park, MD is a surgeon and author of the book, Sleep, Interrupted: A physician reveals the #1 reason why so many of us are sick and tired. Endorsed by New York Times best-selling authors Christiane Northrup, M.D., Dean Ornish, M.D., Mark Liponis, M.D., Mary Shomon, and many others. http://doctorstevenpark.com.

how to replace a spun bearing?

we have been replacing everything in the ngine to get this knocking noise to stop. replaced push rods, exhaust valves lifters gaskets shaved the heads and re-adjusted the rockers. rhe only thing left is to change the bearings incase one is spun. its a 97 camaro rs 3.8, can i replace the bearings without pulling the engine? if so how?

You will have to pull the engine to replace crank bearings. If the bearing has "spun" it means it has stuck to the crank & is spinning in the con-rod. If this was the case you would have virtually little or no oil pressure. If the oil pressure is in the normal range then a wrist pin is the likely culprit. This would require complete disassembly & a full rebuild.

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