The Importance Of Preventative Maintenance

The first new car I ever bought was a 1995 Ford Escort Wagon. It got GREAT gas mileage (which was important for my 25 mile one-way commute to the day job), and had ample room to haul my keyboards & amplifier rig (which was just as important to my side hustle as a potential rock star). Since it only had four miles on the odometer – and, it was the first purchase I ever financed over a period of YEARS, I decided to follow the owner’s manual’s maintenance schedule religiously. And it paid off: I got eleven years and just shy of 200,000 miles out of one of the least expensive cars ever made. It was actually still running like a top when I sold it to “upgrade” to a minivan, which suited my needs at the time for a vehicle that fitted the car seats for our little boys (who are now a U.S. Marine and a hippie college student, respectively). I actually followed the maintenance schedule for that minivan too, and got 14 years & almost 180,000 miles out of it, without a major breakdown.

Whether you call it “preventive”, “preventative”, “scheduled”, or “planned” maintenance, there’s an old adage that applies in any case:

“If you don’t plan maintenance, it’ll plan itself without regard to your schedule.”

While following the proverbial “owner’s manual’s maintenance schedule” doesn’t guarantee against catastrophic failures, it’s awfully good insurance against them. For your privately owned vehicles, I encourage you to follow the owner’s guide as best you can. For your compressed air system – from the compressor to the devices it provided compressed to (and everything in between) – there’s likely similar documentation to follow, and for good reason. Consider:

  • Air compressor maintenance. Failure to properly maintain a compressor can increase energy consumption by not keeping it operating as efficiently as possible. For example, just like not periodically replacing your car engine’s air filter will impact your gas mileage, failure to do the same for your compressor’s intake air filter will impact its production of compressed air.
  • Air leaks are costly. Not only do they waste the money you spent on running the compressor (a leak that’s equivalent to a 1/16″ diameter hole costs you over $700.00 annually – let me know if you want to do the math on that), your system pressure takes a hit too. Pressure drop caused by those leaks (plural because there’s rarely just one) can create what’s known as “false demand”, which costs you money as well: every 2psi increase in compressor discharge pressure makes for a 1% increase in power consumption. So, it’s really important to stay on top of them. Regularly scheduled surveys with an instrument like EXAIR’s Model 9207 Ultrasonic Leak Detector allows you to quickly find – and then fix – those leaks.
EXAIR Model 9207 Ultrasonic Leak Detector comes with everything you need to find out if you have a leak (with the parabolic disc, lower right) and then zero in on its exact location (with the tubular extension, bottom).
  • Filters, part 1: I already mentioned the compressor intake filter above, but the rest of the filters in the system need attention from time to time as well. Filter manufacturers typically call for replacing the element in a filter when pressure drop reaches a certain point. I’ve seen published values of 2-5psi for that. Of course, that may not occur at a convenient time to shut down everything downstream of that filter, so lots of folks replace those elements as part of planned maintenance evolutions that require depressurization of that particular part of the system anyway. Dirty filters mean you have to increase their inlet pressure to maintain the same outlet pressure you had when they were clean – and the same 1% increase in power consumption for a 2psi pressure increase applies here too.
  • Filters, part 2: most compressed air operated products have small passages that the air has to flow through, and without filtration, those can get clogged with dirt that the intake filter doesn’t catch, solid particulate from compressor ‘wear & tear’, and rust from header pipe corrosion, just to name the “usual suspects”. An argument could be made that installation & upkeep of properly rated Filter Separators at the point of use of these devices is part of those devices’ planned maintenance. In any case, it’s akin to the awfully good insurance against catastrophic failures I mentioned earlier.
Good engineering practice calls for point of use filtration and moisture removal, such as that provided by EXAIR Filter Separators.

Again, many of the components that make up a typical industrial compressed air system will have a manufacturer’s recommended maintenance schedule, but if they don’t, how can you properly plan for it? Monitoring of certain system parameters can be a valuable tool for determining how often some planned maintenance should be performed:

  • Power consumption of the compressor. The benefit of measuring & logging this on a regular basis is, if you see sudden changes, you can start looking for what’s causing them. Maybe a bearing or belt is wearing out, some leaks have popped up, or a filter’s clogged. In any case, it’s an indication that SOMETHING needs attention. Large industrial compressors might even have power monitoring in their control scheme. If not, there ARE other parameters you can measure…like:
  • Pressure and flow. EXAIR’s Pressure Sensing Digital Flowmeters make monitoring these parameters quick and easy. Managing the readings can be done with our USB Data Logger, or you can get it on your computer, via a Zigbee Mesh Gateway, with our Wireless Models.
EXAIR Digital Flowmeters are made for iron, copper, or aluminum compressed air pipe in sizes from 1/2″ to 8″ diameters. Options include Pressure Sensing, Wireless Output, USB Data Logger, Hot Tap, and Metric display.

At EXAIR, we’re committed to helping you get the most out of your compressed air system. If you’d like our help with that, give me a call.

Russ Bowman, CCASS

Application Engineer
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Featured image courtesy of Compressor1creative commons license

Manufacturing’s 4th Utility: Compressed Air System Components

In any manufacturing environment, compressed air is critical to the operation of many processes. You will often hear compressed air referred to as a “4th utility” in a manufacturing environment. The makeup of a compressed air system is usually divided into two primary parts: the supply side and the demand side. The supply side consists of components before and including the pressure/flow controller. The demand side then consists of all the components after the pressure/flow controller.

The first primary component in the system is the air compressor itself. There are two main categories of air compressors: positive-displacement and dynamic. In a positive-displacement type, a given quantity of air is trapped in a compression chamber. The volume of which it occupies is mechanically reduced (squished), causing a corresponding rise in pressure. In a dynamic compressor, velocity energy is imparted to continuously flowing air by a means of impellers rotating at a very high speed. The velocity energy is then converted into pressure energy.

Still on the supply side, but installed after the compressor, are aftercoolers, and compressed air dryers. An aftercooler is designed to cool the air down upon exiting from the compressor. During the compression, heat is generated that carries into the air supply. An aftercooler uses a fan to blow ambient air across coils to lower the compressed air temperature.

When air leaves the aftercooler, it is typically saturated since atmospheric air contains moisture. In higher temperatures, the air is capable of holding even more moisture. When this air is then cooled, it can no longer contain all of that moisture and is lost as condensation. The temperature at which the moisture can no longer be held is referred to as the dewpoint. Dryers are installed in the system to remove unwanted moisture from the air supply. Types of dryers available include: refrigerant dryers, desiccant dryers, and membrane dryers.

Also downstream of the compressor are filters used to remove particulate, condensate, and lubricant. Desiccant and deliquescent-type dryers require a pre-filter to protect the drying media from contamination that can quickly render it useless. A refrigerant-type dryer may not require a filter before/after, but any processes or components downstream can be impacted by contaminants in the compressed air system.

Moving on to the demand side, we have the distribution system made up of a network of compressed air piping, receiver tanks when necessary, and point of use filters/regulators. Compressed air piping is commonly available as schedule 40 steel pipe, copper pipe, and aluminum pipe. Some composite plastics are available as well, however PVC should NEVER be used for compressed air as some lubricants present in the air can act as a solvent and degrade the pipe over time.

Receiver tanks are installed in the distribution system to provide a source of compressed air close to the point of use, rather than relying on the output of the compressor. The receiver tank acts as a “battery” for the system, storing compressed air energy to be used in periods of peak demand. This helps to maintain a stable compressed air pressure. It improves the overall performance of the system and helps to prevent pressure drop.

Finally, we move on to the point-of-use. While particulate and oil removal filters may be installed at the compressor output, it is still often required to install secondary filtration immediately at the point-of-use to remove any residual debris, particulate, and oil. Receiver tanks and old piping are both notorious for delivering contaminants downstream, after the initial filters.

Regulator and filter

In any application necessitating the use of compressed air, pressure should be controlled to minimize the air consumption at the point of use. Pressure regulators are available to control the air pressure within the system and throttle the appropriate supply of air to any pneumatic device. While one advantage of a pressure regulator is certainly maintaining consistent pressure to your compressed air devices, using them to minimize your pressure can result in dramatic savings to your costs of compressed air. As pressure and flow are directly related, lowering the pressure supplied results in less compressed air usage.

EXAIR manufactures a wide variety of products utilizing this compressed air to help you with your process problems. If you’d like to discuss your compressed air system, or have an application that necessitates an Intelligent Compressed Air Product, give us a call.

Tyler Daniel, CCASS

Application Engineer
E-mail: TylerDaniel@EXAIR.com
Twitter: @EXAIR_TD

Compressor Image courtesy of Compressor1 via Creative Commons License

Drying Supply Side Air With Heat of Compression Dryers

The supply side of a compressed air system has many critical parts that factor in to how well the system operates and how easily it can be maintained.   Dryers for the compressed air play a key role within the supply side are available in many form factors and fitments.  Today we will discuss heat of compression-type dryers.

Heat of compression-type dryer- Twin Tower Version

Heat of compression-type dryers are a regenerative desiccant dryer that take the heat from the act of compression to regenerate the desiccant.  By using this cycle they are grouped as a heat reactivated dryer rather than membrane technology, deliquescent type, or refrigerant type dryers.   They are also manufactured into two separate types.

The single vessel-type heat of compression-type dryer offers a no cycling action in order to provide continuous drying of throughput air.  The drying process is performed within a single pressure vessel with a rotating desiccant drum.  The vessel is divided into two air streams, one is a portion of air taken straight off the hot air exhaust from the air compressor which is used to provide the heat to dry the desiccant. The second air stream is the remainder of the air compressor output after it has been processed through the after-cooler. This same air stream passes through the drying section within the rotating desiccant drum where the air is then dried.  The hot air stream that was used for regeneration passes through a cooler just before it gets reintroduced to the main air stream all before entering the desiccant bed.  The air exits from the desiccant bed and is passed on to the next point in the supply side before distribution to the demand side of the system.

The  twin tower heat of compression-type dryer operates on the same theory and has a slightly different process.  This system divides the air process into two separate towers.  There is a saturated tower (vessel) that holds all of the desiccant.  This desiccant is regenerated by all of the hot air leaving the compressor discharge.  The total flow of compressed air then flows through an after-cooler before entering the second tower (vessel) which dries the air and then passes the air flow to the next stage within the supply side to then be distributed to the demand side of the system.

The heat of compression-type dryers do require a large amount of heat and escalated temperatures in order to successfully perform the regeneration of the desiccant.  Due to this they are mainly observed being used on systems which are based on a lubricant-free rotary screw compressor or a centrifugal compressor.

No matter the type of dryer your system has in place, EXAIR still recommends to place a redundant point of use filter on the demand side of the system.  This helps to reduce contamination from piping, collection during dryer down time, and acts as a fail safe to protect your process.  If you would like to discuss supply side or demand side factors of your compressed air system please contact us.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

Heat of compression image: Compressed Air Challenge: Drive down your energy costs with heat of compression recovery: https://www.plantservices.com/articles/2013/03-heat-of-compression-recovery/

Compressed Air Efficiency Results in Better Business!

Time and time again we write about how compressed air is considered the fourth utility in a manufacturing setting. Compressed air is a great resource to use, however it needs to be used responsibly!

How you use it in your business is important, for a couple of key considerations:

The Cost of Compressed Air

Compressed air isn’t free.  Heck, it isn’t even cheap.  According to a Tip Sheet on the U.S. Department of Energy’s website, some companies estimate the cost of generation at $0.18 – $0.30 per 1,000 cubic feet of air.  A typical industrial air compressor will make 4-5 Standard Cubic Feet per Minute per horsepower.  Let’s be generous and assume that our 100HP compressor puts out 500 SCFM and is fully loaded 85% of the time over two shifts per day, five days a week:

500 SCFM X $0.18/1,000 SCF X 60 min/hr X 16 hr/day X 5 days/week X 52 weeks/year =

$22,464.00 estimated annual compressed air cost

So to minimize the compressed air use and the over all generation costs there are six easy steps to follow!

  1. Measure: the air consumption You must create a baseline to understand your demand requirements. How can you measure your improvements if you do not understand your total demand or baseline? Installing an EXAIR Flow Meter to your main air lines will help identify the amount of compressed air demand you have and help identify areas of concern.
  2. Find and fix leaks in the system: The repair of compressed air leaks is one of easiest ways to gain energy savings. In most cases all you need is a keen sense of hearing to locate a leak. Once a you have confirmed a leak then the make the necessary repairs. Harder to find leaks may require tools such as EXAIR’s Ultrasonic Leak Detector. This is a hand held high quality instrument that can be used to locate costly air leaks.
  3. Upgrade your blow off, cooling and drying operations: Updating your compressed air process tooling can save you energy and help you comply with OSHA noise and safety regulations. An example would be to replace old blow off or open pipe systems with EXAIR Safety Air Nozzles. Replacing open copper tubes or pipes can amount up to 80% air savings. You achieve lower sound levels and significant energy savings.
  4. Turn off the compressed air when it isn’t in use: It sounds obvious but how many times has an operator left for a break or lunch and doesn’t shut off the compressed air for his/her station? The minutes add up to a significant amount of time annually meaning there is opportunity for energy savings. The use of solenoid valves will help but EXAIR’s Electronic Flow Control (EFC) will dramatically reduce compressed air costs with the use of a photoelectric sensor and timing control.
  5. Use intermediate storage of compressed air near the point of use: The use of storage receivers can improve your overall system efficiency in a number of ways. For example, using a main air receiver at the compressor room can make load/unload compressor control more efficient. Localizing receiver tanks such as EXAIR’s 9500-60 sixty gallon receiver tank by the point of use for a high demand process will stabilize the demand fluctuations allowing a more fluid operation.
  6. Control the air pressure at the point of use to minimize air consumption: The use of pressure regulators will resolve this issue. Using regulators you can control the amount of air being processed at each point of use. EXAIR offers different sized pressure regulators depending upon your air line and process requirements. Regulating the compressed air to the minimum amount required and will reduce your overall demand resulting in annual savings and a payback schedule.

Health & Safety

Injuries and illnesses can be big expenses for business as well. Inefficient use of compressed air can be downright unsafe.  Open ended blow offs present serious hazards, if dead-ended…the pressurized (energized) flow can break the skin and cause a deadly air embolism.  Even some air nozzles that can’t be dead ended (see examples of cross-drilled nozzles on right) cause a different safety hazard, hearing loss due to noise exposure.  This is another case where EXAIR can help.  Not only are our Intelligent Compressed Air Products fully OSHA compliant in regard to dead end pressure, their efficient design also makes them much quieter than other devices.

Efficient use of compressed air can make a big difference in the workplace – not only to your financial bottom line, but to everyone’s safety, health, and livelihood.  If you’d like to find out more about how EXAIR can help, give me a call.

Jordan Shouse
Application Engineer

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