Torque Values and Tapered Threads – Do They Go Together?

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Over the past few weeks, I have been working on various cars in the garage with some good friends. We generally get together and help each other out to make the jobs go easier as well as help each other learn more about keeping our family’s vehicles safe and even helping out some others that don’t have the means to work on their own vehicles. Throughout these repairs, we always end up in some type of discussion over something fairly technical. Sometimes it is the proper installation of a part such as take the bolts to snug, back them out, then torque to half the total torque value, back off again, then finally tighten to the complete torque.

We also share different ways of doing the jobs, such as how to lessen the amount of hot oil you are about to pour all over your hand, or how to get that rusted bolt out without a torch and without breaking it. One discussion that comes up quite frequently is torque specs and then the torque spec for a tapered thread.

In case you were not aware, the NPT or BSPT (male) inlets on EXAIR products are both a tapered thread. Tapered threads are generally used on pipe fittings under pressure to seal better and provide a secure engagement. When comparing this to a standard bolt, or straight thread, one is generally accustomed to receiving a torque spec on just how tight to get the fitting or threaded product. For example, the 1/4-20 bolts used in our Super Air Knives are torqued to 7.5 ft-lbs. in order to properly seal the cap, shim, and body together. These are straight threads and thus a torque spec is often driven by the material, size, and thread of the bolt. Torque on tapered threads such as NPT or BSPT fittings is not as easy to find, and not really reliable.

For tapered threads, the engagement of the thread is not always at the same point due to differing tolerances on thread dimensions. These differences create different points of thread engagement with the corresponding thread it is tightening into. For these scenarios, the torque specification is not always best suited as a numeric value. If you search hard enough you can find a table like the one shown below, but again, not the best value to use when installing a tapered thread.

Size in-lbs N-m
1/16″ 5 0.57
1/8″ 7 0.79
1/4″ 16 1.81
3/8″ 23 2.6
1/2″ 30 3.39
3/4″ 54 6.1
1″ 78 8.81

I personally would not use a straight numeric torque when tightening something with stainless steel thread into a brass fitting, or other dissimilar materials together. For this scenario, I would recommend using something like the table below. The TPFT value is, turns past finger tight. This means you would snug the super air nozzle, vortex tube, or other fittings by hand to finger tight. Then using a wrench or two if needed, turn the fitting to the correct number of revolutions for the given thread size. By utilizing this method and the correct amount of thread sealant, see John Ball’s video blog below, you can ensure there will not be a concern on whether or not the joint will leak and also if the fitting is tight enough.

NPT Size TPFT
1/8″ 2-3
1/4″ 2-3
3/8″ 2-3
1/2″ 2-3
3/4″ 2-3
1″ 1.5-2.5

If you would like to discuss torque settings, installation of your engineered compressed air solution, or even what might be wrong with your minivan, contact us.

Brian Farno
Application Engineer/Garage Mechanic Extraordinaire
BrianFarno@EXAIR.com
@EXAIR_BF

Not All Quick Disconnects Are Equal

Quick disconnect pneumatic fittings have been a staple in any manufacturing facility I have ever visited in my 10+ years as part of the manufacturing world.   The fact is, they have been around for a lot longer than 10 years.   The style we see most often is the 1/4″ Quick Disconnect Fitting, and we are typically troubleshooting a lack of air volume problem because they are not sized properly for the application.  These can be found in any industrial supply companies catalog, your local hardware stores, and even auto parts stores.   Quick Disconnects are even sold with certain EXAIR Industrial Housekeeping products, the key being they are properly sized.

Properly sizing the quick disconnect is a critical step in the process of deciding how to lay out your piping system as well as how to ensure products operate at optimal performance.  As you can see in the picture above, the two quick disconnects on the left are both larger quick disconnects as well as larger NPT thread sizes.   The two on the right are smaller and probably a bit more common to see.  Also notice the thread sizes on each, these are also manufactured in many other NPT thread options.   The through hole on the quick disconnects is decided by the size of the QD, not the thread size on the other end.   The example I am illustrating is comparing the 3/8 NPT and 1/4 NPT quick disconnects: Even though you can have 3/8 NPT threads, your throat diameter of the QD is still restricted to .195″ I.D., the same as the 1/4 NPT.  This can be a large restriction on a product with a 3/8 NPT thread size.

The Inner Diameters of the Quick Disconnects

Also to be noted is that all QD’s of the same size are not made equally, tests have shown that you can lose as much as 20 psi through a quick disconnect and up to 40 psi when not properly matched with the female QD.   This leads to the next step which is to ensure that you are not purchasing a QD on appearance.  MAke sure to choose the QD designed to permit the amount of air you need to operate your point of use product without a volume or pressure loss.

These two points are reasons why quick disconnects can diminish your point of use compressed air product performance.  If you have questions on which size to use with your EXAIR product or need help determining why your point of use product is not performing how you would like, contact us.

Brian Farno
Application Engineer Manager
BrianFarno@EXAIR.com
@EXAIR_BF

 

There IS a Better Way to Vacuum

I spent some time this past weekend straightening up my garage. It wasn’t all that bad, but it had become a bit cluttered…over the past few weeks, it became the staging area for Christmas presents, and then, right after Christmas, it served as the ingress/egress area (for provisions, laundry, etc.) for a long weekend of winter camp for my sons, while my lovely bride and I enjoyed some R&R at a quaint little cabin retreat.

Then we were back to real life, and a situation not unlike those cosmic alignments of the planets that make astrologers wonder and astronomers marvel…both of our cars were due for an oil change at the EXACT SAME TIME.  As I was pushing the broom across the garage floor, a couple of thoughts crossed my mind. First, I have a teenage son with tremendous athletic ability, who I’m sure is more than capable of using a broom…but that’s another story. That led to thinking of other ways I could make the job easier and quicker, and I thought about how cool it would be to have a Chip Vac. That led to my third – and final – thought, about how cool it would be to have an air compressor in my garage. Again; that’s another story.

Perhaps you have a compressed air system, and a need to perform various housekeeping or cleanup operations. Maybe you’re using electric vacuums with motors that burn out and impellers that clog or break. If so, EXAIR’s Chip Vac is just what you’re looking for. There are no moving parts to wear out or break, it’s quieter than electric vacs, and has a powerful suction for fast pickup.

For more aggressive cleanup jobs – say, if your debris is especially dense (steel shot, abrasive garnet, etc.), and/or if there’s a LOT of it, our Heavy Duty Dry Vac may be better suited for you. In addition to the extra power, it’s made of a hardened steel alloy, for extended life, even when used for abrasive materials.

These are available in a variety of sizes (5, 30, 55 and 110 Gallon) and configurations: the standard kit includes everything you need to turn an open top drum into a powerful air-operated industrial vacuum. Our Deluxe Kits add tools and a Drum Dolly for added convenience and flexibility, and our Premium Kits include a drum.

For smaller, more portable jobs, our Vac-u-Gun Systems are just the thing. The Model 6192 Collection System comes with an assortment of tools and a re-usable bag with a shoulder strap. The Model 6292 Transfer System replaces the bag with a 10 foot vacuum hose. The Model 6392 All Purpose System gives you both the hose and the bag.

If you have a need for long lasting, durable, maintenance free Industrial Vacuums, EXAIR has what you’re looking for. We look forward to seeing how we can help with your clean up!

Russ Bowman
Application Engineer
EXAIR Corporation
(513)671-3322 local
(800)923-9247 toll free
(513)671-3363 fax
Web: http://www.exair.com
Blog: https://blog.exair.com/
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If Money Weren’t An Issue.

For every year I grow older I find it harder and harder to open my wallet for certain things.  I guess some would say “cheap” where I believe I have just learned from experience the things that I prefer to keep my money for.  However, if money weren’t an issue there is plenty I would love to indulge in.  For instance, a garage with enough “toys” to keep myself and any number of friends race needs met, or a driveway like the video below.

At this current point in my life, I won’t have to worry about the upkeep on either of those.  However, there is one thing I do have to worry about and that is the upkeep and cost of compressed air.   While some operators believe compressed air is free or that a single blowgun with no engineered solution really doesn’t cost that much, they are sadly mistaken.  It is because of this that EXAIR offers the most efficient way to use your compressed air in many point of use applications.

Take the real life example below.

It boils down to this:

Less Compressed Air Usage = Lower Operating Costs = More Profit = Race Track in Front Yard.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF