Q4 2019

Air Compressors and Compressed Air Systems

COMPRESSED AIR SYSTEMS and components will be the subject of this series of articles. In drycleaning and laundry, compressed air is mostly used to expand and/or contract cylinders to actuate valves and position parts of machinery (the head on your pants press or the buck on your shirt unit). In addition, compressed air is also used to “blow out” moisture and debris from fabric on your spotting board, and on far too rare occasions, dust and lint from the surface of machinery.

Some of the basic components of the compressed air system we will cover are as follows:

  1. Air Compressor
  2. Filters
  3. Regulators
  4. Lubricators
  5. Valves
  6. Cylinders

Well what is compressed air?  The answer is, air forced into a closed container raising its energy level and storing this air as a source of energy for later use. This process is called “compression.” The AIR COMPRESSOR, a device I’m sure almost all readers could find in your plant, is designed to accomplish this task. Unlike steam, which once outside the boiler has one basic quality, pressure; the compressed air powering your equipment has many important qualities. Pay attention to these qualities and you’ll be rewarded with smooth trouble-free operation of both the air compressor and the productive machinery it powers. Ignore them and you’ll leave yourself open to lost production time, higher utility and more frequent repair costs. There are several subjects to cover but first a warning:

COMPRESSED AIR CAN BE DANGEROUS!

BEFORE ATTEMPTING ANY MAINTENANCE TO YOUR AIR COMPRESSOR OR COMPRESSED AIR SYSTEM BE SURE THE ELECTRIC POWER IS OFF, NO SAFETY DEVICES HAVE BEEN DEFEATED AND THE INTERNAL AIR PRESSURE HAS BEEN BLED OFF UNTIL THERE IS NO AIR PRESSURE PRESENT.

The Air Compressor – An air compressor is comprised of a pump which compresses the air, a tank where the compressed air is stored for use and several components including check and relief valves as well as electrical and mechanical pressure switches located in different areas on the compressor used to ensure its safe operation. Several families of compressor pumps exist but I’ll limit this discussion to reciprocating compressors, the most common in our industry.

Reciprocating compressors use pistons moving inside cylinders working with associated valves to compress the air. They’re constructed similar to a two-stroke gasoline engine and require basically the same type of maintenance.

In a gasoline engine expanding gases generated by the explosion of a mixture of gasoline/air vapor pushes a piston, linked to a crankshaft to turn a flywheel and generate rotary motion. In an air compressor an electric motor provides the rotary motion and is linked to a flywheel (usually via belts) to rotate the crankshaft. The crankshaft translates rotary motion into reciprocating motion by sliding a piston inside a cylinder and compressing the air in front of the piston head. This works in the reverse principal of the gasoline engine.

Now, as you can imagine there are lots of moving parts in this portion of the compressor along with seals and gaskets requiring lubrication. To minimize friction and wear all this linear and rotary motion must take place in an oil bath. Not just any oil, but oils engineered for the type of lubrication service required for air compressors. Not only must the oil be designed to be compatible with the rubber, plastic, and metal parts in the compressor, it must not degrade components in the machinery that use the compressed air.

Check the oil levels in compressors weekly; there should be a sight glass toward the bottom of the compressor pump. With the compressor off, a level of about ½ way up the height of the sight glass should be visible. Add oli if it is lower.  The oil itself should be drained and disposed of properly then replaced at least once annually. A fill as well as drain plug is usually located near the sight glass.

A second maintenance concern is the belts coupling the electric motor to the compressor pump. These belts are subject to wear and need to be monitored at least monthly. You’ll know when they begin to fail because you’ll hear them squeal when the compressor starts. Do not use “belt dressing” to avoid adjusting or replacing failing belts.

BE SURE THE ELECTRIC POWER IS OFF BEFORE ATTEMPTING TO ADJUST OR REPLACE BELTS. MAKE SURE THERE IS NO RESIDUAL AIR PRESSURE IN THE RECEIVER TANK. ALWAYS REPLACE THE BELT GUARD WHEN FINISHED.

When the belts are properly adjusted pressing your thumb against the belt about ½ way between the motor pulley and flywheel should result in about a ½ displacement on the belt. When adjusting belt tension do not overtighten the belts, this causes premature belt wear and bearing failure. Look carefully at your belts. If there are loose threads, separations between layers of rubber, or cracks across the face of the belt do not wait, replace them. Belts should always be replaced with new ones with the exact specifications as the originals.

I’ll continue this subject next issue with more easily accomplished tasks that can help you save big bucks.

 

Bruce Grossman is the Chief of R&D for EZtimers Manufacturing. EZtimers is the manufacturer of the EZ Level return tank water level control which replaces the troublesome ball float valve in the return tank. The SAHARA and DROP IN THE BUCKET line of high purity separator water mister/evaporators also the TATTLER steam trap tester an accurate and easy to use device are also part of our EZtimer product line. See our Ad in this issue and for further information on EZtimers products visit  www.eztimers.com   Please address any questions or comments for Bruce to  bruce@eztimers.com  or call 702-376-6693.

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