Is PVC Pipe Alright to Use with Compressed Air?

A question arises every now and then on whether or not PVC pipe, yes the stuff from your local hardware store that says it is rated for 200 psi, is safe to use as compressed air supply line.   The answer is always the same,  NO! OSHA agrees – see their statement here.

Schedule 40 PVC pipe is not designed nor rated for use with compressed air or other gases.  PVC pipe will explode under pressure, it is impacted significantly by temperature and can be difficult to get airtight.

PVC pipe was originally designed and tested for conveyance of liquids or products that cannot be compressed, rather they can be pressurized.   The largest concern is the failure method of the piping itself.   When being used with a liquid that cannot be compressed, if there is a failure (crack or hole) then the piping will spring a leak and not shatter.   When introducing a compressed gas, such as compressed air, if there is a failure the method ends up being shrapnel.  This YouTube video does a good job of illustrating how the pipe shatters.

While it may seem that it takes a good amount of pressure to cause a failure in the pipe, that is often not the case.  I have chatted with some local shop owners who decided to run PVC as a quick and cheap alternative to get their machines up and running.

They each experienced the same failures at different points in time as well.  The worst one was a section of PVC pipe installed over a workbench failed where an operator would normally be standing. Luckily the failure happened at night when no one was there.  Even though no one got injured this still caused a considerable expense to the company because the compressor ran overnight trying to pressurize a ruptured line.

Temperature will impact the PVC as well. Schedule 40 PVC is generally rated for use between 70°F and 140°F (21°-60°C). Pipes that are installed outside or in non temperature controlled buildings can freeze the pipes and make them brittle.

If you haven’t worked with PVC before or do not let the sealant set, it can be hard to get a good seal, leading to leaks and a weak spot in the system.

The point of this is the cheapest, quick, and easy solutions are more often , the ones that will cost the most in the long run.

If you would like to discuss proper compressed air piping and how to save compressed air on your systems, please contact us.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

 

Image courtesy of: Dennis Hill, Creative Commons License

Heavy Duty Line Vac is a Simple Solution When Mechanical Conveyors Fail

 

Line Vacs can convey many things.
Line Vacs can convey many things.

 

A manufacturing plant had a machine that would process 6mm ceramic beads into small medical components.  They used a screw type conveyor to move the ceramic beads from a large container into a hopper above the machine.  In this situation, the customer called EXAIR prior to determining which mechanical component failed.  They contacted the conveyor manufacturer for assistance.  Because of the complexity of the conveying system, it would take time to evaluate.  They had to determine if it was the motor, the gear box, the shaft, or electrical system.  Depending on which item that failed, there was a good chance that it would not be in stock.  With this length of downtime, it would cost the company much money and delays in shipments. The operation had to be shut down until they could find a way to keep the hopper filled with ceramic beads.  Being that they were under the gun, they contacted EXAIR to see if we could help.

Heavy Duty Line Vac

Heavy Duty Line Vac

In discussing their layout, the hopper was 10 feet away from the supply container, and the opening of the hopper was 10 feet above the floor.  These lengths were well within the limits of the EXAIR Air Operated Conveyors.  I suggested the model 152200 Heavy Duty Line Vac Kit.  This unit has the highest conveyance rate, and it can move items in the range of plastic pellets to steel shot.  It does not have any moving parts, so it makes it very simple, reliable, and long lasting.  The Heavy Duty Line Vac is made of a hardened steel that makes it very resistant to abrasion.  The next question he asked was if we had it in stock.   We did!!!  EXAIR stocks every cataloged model number for same day shipping with orders placed before 3 p.m. EST.  We were able to ship the Heavy Duty Line Vac that same day to get his operation back up and running.  He did mention to me afterwards that he wished he had at least one Heavy Duty Line Vac on his shelf as a backup system.  It could have saved his company an entire day of downtime.

If your company relies on mechanical conveying systems to move product, you may want to have an EXAIR Air Operated Conveyor on hand just in case of an emergency.  When things go wrong, you do not want to be down any longer than needed.  If you need help in sizing the correct Line Vac for your application, you can contact an Application Engineers at EXAIR.

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

The (Not So) Dreaded Warranty Claim Call, Resolved

A couple of weeks ago, I wrote about warranty claims…one, specifically, that I had recently received (it’s still worth a look even if you remember it well, just for another chance to see the old luggage commercial with the gorilla again.) I also advised my readers to stay tuned, which reminds me of another blast from my past as a kid who watched way too much TV in the early 1970’s…

same_bat-time_same_bat-channel

We did, in fact, receive and evaluate the failed Stay Set Hose. This is a formal process by which our Quality Control team analyzes all the information that I can give them as to the application, installation, and use of the product. They then perform a detailed inspection, evaluation, and test (if needed) of the product in question. I won’t say we never find manufacturing or assembly problems, but our records indicate we’ve never found the same one twice…we’re keenly aware that the first time may be a mistake, but the second time is a choice.

More often than not, we find the problem is due to easily correctable installation, operation, or air supply problems. In this case, when we inspected the bendable element, we could see that it had been subjected to an unsupported, twisting motion, which had fatigued it at the point where it was bent, and sheared it away from its internal connection.  The customer and I had already gone over the common best practices for their use (which included properly supporting the hose while bending…see pictures below,) so they got a replacement Stay Set Hose, and are back in operation.

Hose is being bent with one hand, with no support at the bending point.  DON'T DO THIS.
Hose is being bent with one hand, with no support at the bending point. DON’T DO THIS.
Hose is being held firmly at connection end, providing support for the element's connection inside the fitting.  DO THIS INSTEAD.
Hose is being held firmly at connection end, providing support for the element’s connection inside the fitting. DO THIS INSTEAD.

If you’ve got questions about how EXAIR’s Intelligent Compressed Air Products…and accessories…can make better use of your compressed air, give me a call.

Russ Bowman
Application Engineer
(513)671-3322 local
(800)923-9247 toll free
(513)671-3363 fax
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Dirty Compressed Air Consequences Are Avoidable

I would like to discuss the importance of clean and dry filtered air.  This all comes from some discussions I have had with customers over my time here at EXAIR, as well as from my time in the machine tool industry. It is notable to state that we simply ask for clean/dry air to run through our products, not “instrument” or “process” air which is typically held at a different pressure, temperature, or volume and can be more expensive to generate. All of EXAIR’s products use general plant air and can be cleaned up with simple point of use filters.

Clean and dry compressed air is essential for ensuring a long and easy life of almost any compressed air product.   One product in particular that I have some data on is the EXAIR Line Vac.  The pictures below show the inside wall of a Stainless Steel Line Vac.  This unit was used in a harsh outdoor environment.   The compressor was not maintained and did not have any form of filtration on the lines feeding the Line Vac unit. The first picture shows where all the dirt and particulate were impacting the internal generator wall as it entered the air chamber.

Damaged Generator

The two dark grey marks are actually the impact points on the unit.   There is only one air inlet on the Line Vac, this means that the unit was taken apart during the two months and actually inspected then put back together and the generator was rotated slightly during this process.  These spots are similar to what sandblasting does to metal, just to illustrate how much particulate was in the air stream. Since the air has not yet reached its full velocity within the Line Vac, it has left only those visible surface blemishes.

As the air begins to exit the array of small generator holes it begins to rapidly increase in velocity while it is trying to expand to atmospheric conditions.  Because of this increased velocity, the wear the generator holes experience is greater and as seen below it is causing some extreme wear.

Worn Generator Holes

To give you an idea of what a new generator should look like is below. Here you can see uniform holes that go precisely through the generator.

IMG_4283

To prevent a disaster like this from happening to your end-use compressed air products, all you need are some simple, low maintenance filters.   EXAIR offers dirt / water filter separators that will filter your compressed down to 5 micron particulate size.   The will catch the good majority of rust, water, and dirt within your compressed air system.   Then you can also install an oil removal filter which will filter all oils and particulate out of your compressed air system down to 0.03 micron particulate level.

Each of these units are great point of use filtration to keep any of your processes from experiencing what this Line Vac experienced.   If you have any questions about the quality of your compressed air or why you are seeing failures in product on your compressed air system, contact us.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF