Tag: compressor

Any Machine Is A Smoke Machine If You Operate It Wrong Enough

Published on by Russ BowmanLeave a comment

While most folks think this old adage applies only to personnel not being familiar with the OPERATION of machinery, it’s also a reminder that ‘operating it right’ necessarily includes keeping up with regularly scheduled preventive maintenance. This includes pretty much anything with moving parts and components in a system that fluids might flow through. But today, I’m going to focus on certain parts of a typical industrial compressed air system. Failing to change oil in an industrial air compressor, for example, will “let the smoke out” just as fast (and sometimes faster) than anything a day-to-day operator can do to it.

The folks at Compressed Air Challenge are dedicated to (and this is right from their website) “helping you enjoy the benefits of improved performance of your compressed air system.” Their “Best Practices For Compressed Air Systems” stresses the importance of:

  • Proper maintenance as a means to ensure operational efficiencies and systems reliability.
  • Continuous checks for preventive maintenance items.
  • Implementing a detailed system maintenance program, including schedules of required maintenance, and records of its performance.

And that’s just from the introduction. It goes on to list the major components that should be included in this program: the compressor, heat exchanger surfaces, lubricant, lubricant filter, air inlet filter, motors, belts, and air/oil separators. The steps for properly maintaining these components range from standard housekeeping practices, to mechanical operations that are typically performed by trained operators, to services that might be best handled by qualified manufacturer’s representatives:

  • Cleaning: The air compressor itself, and any heat transfer surfaces, have to be kept clean & free of contaminants. Moving parts generate heat, and dirt, scale, corrosion, etc. are essentially insulation that’ll prevent that heat from being dissipated.
  • Lubrication: It’s critical to service the lubricant & any lubricant filtration per the manufacturer’s specifications. Again – not doing this is one of the best ways to “let the smoke out” of any machine.
  • Power transmission components: Regular inspection, including alignment checks, of belts & couplings is probably the 2nd best way (next to lubrication maintenance) of keeping the moving parts of the air compressor, and its drive, in good working order.
  • Intake filter: An air compressor will try to compress anything that’s drawn in with its air intake. If it pulls in particulate, that can damage internal surfaces, especially moving parts with tight tolerances to each other, like pistons & cylinders, scrolls & casings, rotary screws & chambers, impellers & volutes, etc., depending on the type of compressor. Plus, anything that makes its way into your compressed air header will also have a chance to foul up your pneumatic tools & devices, and get on anything that you use compressed air to blow off.
  • Motors & drives: Simply put, if you can’t turn the shaft of the compressor, it won’t compress any air. Periodic checks of electric motor windings, bearings, ‘soft start’ capacitors, phase converters, etc., are among the basic maintenance items that operators can inspect.

In addition to the compressor itself, the air distribution system should be properly maintained as well:

  • Filtration: The intake filter is there primarily to protect the compressor. Many times, the aforementioned tight tolerances between the moving parts in the air end will result in (hopefully) small amounts of particulate being carried over into the compressor discharge. There’s usually a main particulate filter, along with a dryer (for entrained moisture – the intake filter won’t do anything about that either), and possibly even a coalescing filter for oil & oil vapor. Good engineering practice calls for servicing those filters when the differential pressure across them reaches a certain value (5psid is a common one), but those elements, being relatively inexpensive, can also be replaced during regularly scheduled downtime as well.
  • Leak detection & repair: Leaks make the compressor run harder, so any reduction in the amount of compressed air leakage will, by definition, reduce the wear & tear on the compressor. EXAIR makes it easy to find them with the Ultrasonic Leak Detector.
  • Filtration Part 2: Don’t forget about contaminants that can enter the system downstream of the compressor, too. Iron pipe headers are subject to internal corrosion, which can result in rust particulate. Environmental pollution can enter if flanges or fittings are broken & made up during maintenance. Point of use filtration, like EXAIR Automatic Drain Filter Separators, can keep this debris (and any moisture that’s not removed by the compressor’s dryer) out of your pneumatic tools & products.
EXAIR has a number of Accessories and Optimization Products to help you get the most out of your compressed air system.

Compressed air is expensive enough without throwing in a bunch of easily preventable repair costs. Schedule time for maintenance, or it’ll schedule the time for you…and it may even send you a ‘smoke signal’ when it’s ready. If you’ve got questions about getting the most out of your compressed air system, we’ve got answers.

Russ Bowman, CCASS

Application Engineer
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Critical Components of Your Compressed Air System

Published on by Tyler DanielLeave a comment

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 after coolers, and compressed air dryers. An after cooler 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 after cooler uses a fan to blow ambient air across coils to lower the compressed air temperature.

When air leaves the after cooler, 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 Tampere Hacklab via Creative Commons License

Air Compressors: Centrifugal Type.

Published on by johnball2014Leave a comment

There are two main ways to compress air for supplying pneumatic systems; Positive Displacement and Dynamic.  Positive Replacement reduces the volume of air within a confined space to generate pressure.  The dynamic type raises the air pressure by using kinetic energy and velocity with rotating impellers that continuously brings in airflow.  In this blog, I will cover the centrifugal type of the dynamic branch. 

As mentioned, the centrifugal compressor works by transforming kinetic energy and velocity into pressure.  Ambient air passes through guide vanes into the center of a rotating Impeller with radial blades and is then pushed outward by a centrifugal force. This radial velocity of air results in an increase in pressure due to kinetic energy.  Let’s look at the equation for kinetic energy in Equation 1:

Equation 1: 

K = ½ * m * V2  

K – Kinetic Energy (J)

m – mass (Kg)

V – velocity (m/s)

As you can see, the energy increases with the square of the velocity.  How do we increase the velocity?  Let’s look at Equation 2:

Equation 2:

V = w * r

V – linear velocity (m/s)

w – angular velocity (rad/sec)

r – radius (m)

As you can see, as the air travels along the impeller towards the outside, the radius increases.  Since the rotations per second are constant, the velocity will increase.  In combination with Equation 1, you can see how the energy will increase, thus increasing the pressure. 

 With the increase in pressure, you will get an increase in heat.  It is a natural occurrence with air compressors.  Heat from the centrifugal compressor is dissipated with heat exchangers before moving onto the next stage.  Multiple stages are required to raise the pressure to a sufficient level for typical industrial plant requirements.  The most common centrifugal air compressors have two to four stages to generate pressures up to 100 to 150 PSIG.  Centrifugal compressors are near the middle of the road regarding efficiency.  Their typical operating cost is 16 to 20 kW/100 CFM. 

Advantages:

  • Up to 1500 HP systems are available
  • Price per Horsepower drops as system size increases
  • Supplies lubricant-free air
  • Special installation pads are not required for installation

Disadvantages:

  • Costs more Initially
  • Requires specialized maintenance

No matter the type of air compressor that you use, they are very costly to operate.  To help you use them efficiently and safely, EXAIR offers a range of products that can clean, cool, blow, conserve, and convey.  This would include our Super Air Knives, Super Air Nozzles, Safety Air Guns, Cabinet Coolers, and much more.  If you want to save energy, increase safety, and cut costs no matter what size air compressor you have; you can contact an Application Engineer at EXAIR.  We will be happy to help you. 

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

Images Courtesy of the Compressed Air Challenge

The Importance Of Preventative Maintenance

Published on by Russ BowmanLeave a comment

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 Compressor1 – creative commons license