Don't use a needle valve to control your air cylinder speed!

This blog post addresses an issue that is all too common in the industry. That is, people are not always aware of the optimal air cylinder speed for certain applications. We've put together this article with some tips on what you should be looking for to ensure that you're using your air cylinders at the most appropriate speed.

It's important to note before we start that there are many factors beyond just needle valve setting that can affect air cylinder speed and pressure output, such as compression and leak rates, regulator settings, system leakage rates, etc. These are all factors we'll touch on in this blog post, but do keep in mind that there may be other variables that contribute to the air cylinder speed and pressure output you're seeing.

We've put this article together to address the need for an easy reference to the various speeds available to you with a typical needle valve, what these speeds mean and when each of these speeds should be used. We'll also cover some suggestions of what you should look for if you're experiencing an issue with slowing air cylinder speed at higher pressures or a lack of pressure at lower pressures. What you don't need to worry about is what needle valve settings some air cylinder fanatics have been advocating over the past few years.

It's important to note that with most air compressors there's a "sweet spot" where the available pressure delivered by an air cylinder will reach a maximum before the compression output begins to drop back off again. You can typically see this "sweet spot" by raising the air regulator pressure on your compressor, or slowing down the compressor speed and then slowly increasing it, observing how quickly you start seeing changes in your output pressure.

Both of these methods are referring to the compression setting you're using on your compressor. The sweet spot will change from unit to unit and from compressor to compressor as well as from cylinder to cylinder based on age, condition and wear. However, this is typically around a 20-25% increase in regulator pressure from a standard 50% output setting. For example, if the "sweet spot" for your compressor is normally at 70-80 psi (it may be slightly higher or lower depending on factors mentioned above), you'll want to increase the pressure setting on your regulator to approximately 95-100 psi before seeing changes in output pressure again.

The pressure ranges above are the typical "sweet spots" for most compressors, but there may be other sweet spots depending on your compressor, system and use. Therefore, if you're not seeing changes in pressure output when you raise the regulator pressure on your compressor to this range, it's likely that you're not using the air cylinder at the optimal speed. This is a natural progression of efficiency losses that occurs as we try to get more from our compression systems when operating at higher pressures.

One way to help avoid this efficiency loss is to use a needle valve orifice setting (i.e., an adjustable needle valve) on your compressor. This way, you can adjust the needle valve so that you're getting a "sweet spot" closer to the output pressure you need. The issue with this is that a common set of needle valve orifice settings for all compressors may not exist. So, what if you don't have an adjustable needle valve? Not to worry, we'll cover this in more detail below as well!

So to summarize what we just covered…

Picking the correct speed of your air cylinder depends on several factors including the application and how much pressure is available to your system.

Most air cylinder speeds are available in the 65% to 80% range, but these can change from one supplier to another or from compressor model to model.

The actual speed at which you want your air cylinder to run will be determined by looking at your desired system pressure, the compressor output pressure and how quickly you're reaching that pressure on your system.

As noted above, air cylinder speeds may also vary based on system safety, regulator settings and other factors. The sweet spot will also be different for each set of all of these factors for each application.

One possible way to get closer to the output you want, especially when using an adjustable needle valve, is to adjust your needle valve to be faster. Again, this will depend on your compressor and system type.

Another option is to delay the time that your compressor is taking to achieve its desired pressure as you raise the regulator pressure on it by adjusting your needle valve. This will be at the expense of more friction loss and efficiency loss when flowing more air through your compressor at lower pressures (i.e., 70%~80% of maximum).

Another consideration is how much air you're getting at each of these pressure points. For example, with an increase in pressure on the compressor you may not be able to flow all of the air you want through your system before the output pressure drops off again.

So that's it! We hope this blog post was helpful and will help you improve your air cylinder performance. If you have any other tips or suggestions please feel free to leave them as comments! We'll try to answer or incorporate into future articles if appropriate.

Next week we'll continue our series with a blog post covering how to source and ship air cylinders from the United States to various countries worldwide without incurring large import fees!

Until then, thanks for reading. If you have any questions or need additional information, please feel free to contact us at sales@elijincorp.com or (877) 956-4458 ex.2.

Conclusion

The primary point we're trying to get across here is that you don't want to designate a particular speed as the "recommended speed" for any air cylinder. As mentioned, there are variables that determine the correct speed for your air cylinder. These variables include your system type (i.e., powder actuated tools, pneumatic tools or power tools), application and pressure settings on the compressor being used.

We hope this helps clarify why our product literature does not have a recommended speed for each air cylinder that we manufacture, but rather lists general ranges of speeds for our different size and pressure capabilities of air cylinders.