We recently had a customer approach us the SSPC show to discuss the differences between our compressed air drying systems and some of the others in the industry. This particular customer spoke at great length about the size of the air motor on our 1600 CFM air dryer package. They told us that they recently purchased a competitor's package and they were amazed to find out that our air motor was double the size of the competitor's unit. At first, it was merely an observation, but after sending the dryer out on a few rentals, they found that it was quickly becoming a maintenance nightmare. The smaller air motor had to work
harder to spin at the same RPMs and achieve the same approach temperature performance. This additional wear and tear on the air motor caused premature failure and the customer was forced with a tough decision. To rebuild the air motor or spend the money to replace the current air motor with a larger, more suitable size. This is just one example that size does matter.
This guide was written to help you and/or your customers purchase a properly sized air dryer system for your application requirements. One of the biggest issues we come across when helping our customers is their units not working properly due to water in their airlines. Which is usually caused by an incorrectly sized unit.
The most critical part of any portable air drying package is the size of the vessel. Since the dryer vessel is the most critical part of any dryer package, it can also be the most expensive component. Often times, manufacturers will undersize a dryer vessel or use thinner steel to remove some cost out of their portable dryer packages. Knowing operating flow rates and pressures is essential to sizing a compressed air dryer system properly. Take a close look at the questions below before you purchase a compressed air dryer. Knowing the answers ahead of time may save you headaches later due to problems from an undersized dryer package.
To further explain - The bigger the vessel, the more desiccant it can hold and the more SCFM you can flow through the dryer without sacrificing performance. The longer the air remains in contact with the desiccant, the lower the dew point and the better your dew point performance will be at the outlet. Since a larger dryer vessel will hold more desiccant, you will also be able to extend your maintenance cycles.
Below is a recommended vessel size based on your flow at 100 psig, 125 psig, and 150 psig.
|Dryer Example: Van Air Blast Pak Model #||Vessel
|SCFM Flow Rate
@ 100 psig
|SCFM Flow Rate
@ 125 psig
|SCFM Flow Rate
@ 150 psig
Where do I find my operating pressure? Most production machinery lists air consumption in the specifications or operating manual. Digging through old files to find a manual may be tedious, but it’s a sure way to avoid a sizing mistake for the filter and dryer. Plan B is to put a flow meter in the line and actually measure what is going through it. In most applications, the price to rent a flow meter is cheap insurance versus spending money for equipment that’s too big or small and not getting the job done properly.
You Get What You Pay For:
Purchasing a properly sized dryer will save you headaches as well as money from issues caused by an undersized unit. Purchasing an air dryer system is an investment, so make sure it will outlast any application. We all have heard the old adage..."You get what you pay for" and also "Do it right, do it once". Getting a properly sized unit may cost a little more upfront but in the long run but it will save you from breakdowns in the future. In the rental market, longevity of the equipment translates into higher profit from your purchase. Spending a little more on the initial purchase to get a high quality dryer package with oversized components will eliminate down time, improve performance, and reduce maintenance costs. Ultimately it will be more profitable over the 15 year life of the equipment to base your decision on quality and not price alone
As always the technical team here at Van Air Systems is more than willing to share our experiences (good and bad) so that you and your customer get the appropriate size unit for the application. Call 1-800-840-9906 or send an e-mail at any time, we would be happy to work with you.