Posts Tagged ‘Air Compressors’

Ask a Question:
What are some good trouble shooting tips to help me maintain my compressed air system?

Here are some great Air Compressor Trouble Shooting Tips
to help you or anyone providing the regular maintenance for your compressed air system.

Below are listed several very common problems, their probable cause and some usual remedies for the trouble.

Of course, there can be multiple problems and unique circumstances to every compressor issue…but these tend to solve the most common situations.

Low pressure at point of use

Probable Cause: Remedial Action
Leaks in distribution piping: Check lines, connections and valves for leaks
Clogged filter elements: Clean or replace filter elements
Fouled dryer heat exchanger: Clean heat exchanger
Low pressure at compressor discharge: See below

Low pressure at compressor discharge

Probable Cause: Remedial Action
For systems with modulating load controls, improper adjustment of air capacity system:
Follow manufacturer’s recommendation for adjustment of air capacity system

Worn or broken valves Improper air pressure switch setting:  Check valves and repair or replace as required
Follow manufacturer’s recommendations for setting air pressure switch

Improper air pressure switch setting: Follow manufacturer’s recommendations for setting air pressure switch

Water in lines

Probable Cause: Remedial Action
Failed condensate traps: Clean, repair, or replace the trap
Failed or undersized compressed air dryer: Repair or replace dryer.  If you do not have an Compressed Air Dryer, consider adding this equipment.

Liquid oil in air lines

Probable Cause:  Remedial Action
Faulty air/oil separation: Check air/oil separation system; change separator element
Compressor oil level too high:  Follow manufacturer’s recommendation for proper oil level

Dirt, rust or scale in air lines

Probable Cause: Remedial Action
In the absence of liquid water, normal aging of the air lines: Install filters at point of use

Excessive service to load/hour ratio

Probable Cause: Remedial Action
System idling too much:
For multiple compressor system: consider sequencing controls to minimize compressor idle time
Adjust idle time according to manufacturer’s recommendations

Improper pressure switch setting: Readjust according to manufacturer’s recommendations

Elevated compressor temperature

Probable Cause: Remedial Action
Restricted air flow: Clean cooler exterior and check inlet filter mats

Restricted water flow

Remedial Action:
Check water flow, pressure, and quality; clean heat exchanger as needed

Low oil level

Remedial Action:
Check compressor oil level, add oil as required

Restricted oil flow

Remedial Action:
Remove restriction, replace parts as required

Excessive ambient temperature

Remedial Action:
Improper ventilation to compressor; check with manufacturer to determine maximum operating temperature.

Owned & Operated by
Tommy McGuire
McGuire Air Compressors, Inc.
“Real People with Real Air Compressor Experience”

For Champion Air Compressors…

For Reelcraft Hose Reels for Air, Water, Oil & fluid
plus Electric Cord Reels & Welding Cable Reels…

For Arrow Refrigerated Air Dryers
to remove moisture from your compressed air system…

Email us:

Call us:

Mailing address:
McGuire Air Compressors,Inc.
P.O. Box 1100
Graham NC  27253


  • ­­­Does your air pressure keep dropping while you are using your tools & equipment?
  • Have you added or are planning to add new equipment which uses air?
  • Are your air compressors working hard all the time- but you just aren’t sure how to figure how much more horsepower you need?

When your business counts on air – you need to know the valuable formulas and steps to help accurately determine how many CFM you use. You also need to know how to accurately figure how much additional CFM and horsepower you need when considering a new air compressor?

Here are some specific formulas that can help you determine how many CFM you presently use and how many more CFM you need to meet your desired PSIG. We will show you how to take this information and use it to determine how much air compressor horsepower you actually need.

Find out how many CFM your air compressor delivers

1. STOP the compressor unit

2. CLOSE the outlet valve on the tank/air receiver

3. DRAIN the condensate from air receiver until there is 0 PSIG –
then close the drain valve

4. NOTE THE TIME- in minutes & seconds (Best to write it down.) Then START THE UNIT.
When the compressor unit stops and unloads – then NOTE THE TIME again – in minutes & seconds. Convert the minutes into seconds and then total the number of seconds it takes between START and STOP/UNLOAD.

5. NOTE the GUAGE PSIG reading

6. NOTE the Air Receiver/Tank GALLON SIZE


TANK GALLONS x .538* x PSIG divided by SECONDS


You have an 80 gallon tank, your total start to stop/unload time was
3 minutes and 30 seconds. Change the minutes to seconds timed
(60 x 3= 180 seconds plus 30 seconds which totals 210). You will use the total number of seconds (210) and the noted 175 PSIG within the formula as shown below:

80 multiplied by .536 = 42.88
42.88 multiplied by 175 (Example PSIG) = 7504.00
7504.00 divided by 210 (total seconds)= 35.74 CFM delivered

The example shows that the air compressor is delivering 35.74 cfm

Your Response to this evaluation should be to compare this number with what your air compressor manufacturer says your CFM should be and evaluate how efficiently your compressor is running.
If your air compressor is within 10% of manufacturer’s specifications, then the unit is OK, if not – repair unit and recalculate your needs.

Find out how many more CFM you need to
raise your PSIG

1 What is your desired pressure ______?
(Our Example125 psig)

2. What is your present operating pressure_______?
(Our Example 70 psig)

3. Divide desired pressure by present operating pressure
(125 psig divided by 70 psig = 1.79)

4. This gives us the X-factor needed for this formula (1.79 )

Multiply present air compressor cfm (35.74) by your X-factor (1.79)
(35.74 X 1.79= 63.98 This gives you the total cfm needed –
which is 63.98 for our example)

6. Deduct your present cfm from the needed cfm
(63.98 minus 35.74 present cfm = 28.24)

7. This gives you the additional cfm needed to raise your psig to the level you actually need. (which is 28.24 additional cfm for our example)

Translate your answers into how much horsepower
you actually need to operate

Divide your additional cfm needed by 3.5* (see the chart for your *actual compressor type & horsepower)
(28.24 ÷ 3.5 = 8.07 hp, which would be the additional horsepower needed for our example)

This will give you the additional horsepower you actually need.

(We will need to round up the 8.07 hp to 10 hp needed for our example. You will have to round up to the nearest standard
horsepower also.)

*CFM per compressor horsepower chart:

3.5.cfm per hp for small piston compressors ½-30 hp

4 cfm per hp for large piston 40 hp up & small screw compressors
2 hp-30 hp

4.5 cfm per hp for 40 hp-150 hp medium hp screws

5 cfm per hp for 200 hp-2000 hp large screw & centrifugal compressors
Note: Always buy CFM of delivered air at the PSIG you need…not horsepower.

Note: Always invest in at least 20% more CFM than your equipment needs. This will cover extra air usage for such things as air leaks and wear.

Follow these formulas and you can figure just how much more CFM and air compressor horsepower you really need to get the job done!

Compressor Terms you should know:

Cubic Feet Per Minute (cfm) – Volumetric air flow rate.

“psig” means pounds per square inch, GAGE pressure. Gage pressure is the absolute pressure of something, with the atmospheric pressure subtracted. In practice, when someone gives a pressure in just “psi” they probably mean gage pressure. If they mean absolute, they should be using “psia.”

Gauge Pressure – The pressure determined by most instruments and gauges, usually expressed in psig. Barometric pressure must be considered to obtain true or absolute pressure.

Load Time – Time period from when a compressor loads until it unloads.

Unload – (No load) Compressor operation in which no air is delivered due to the intake being closed or modified not to allow inlet air to be trapped.

Receiver – A vessel or tank used for storage of gas under pressure. In a large compressed air system there may be primary and secondary receivers.

Tommy McGuire

McGuire Air Compressors, Inc.
“Real People with Real Compressor Experience”


Figuring the correct pipe size for your compressed air distribution system is an important task. 
Pipe that is sized too small can create big pressure losses and reduce operating efficiency. Replacing piping is costly.  On average, 70% of a contracted piping job goes for labor and 30% for materials.

Do you know the biggest mistakes made in figuring compressed air piping sizes?
Many people who plan the piping never consider the fittings or the future.

Every pipe fitting creates a certain amount of increased frictional air loss that is equal to a specified length of pipe.
For every 100 feet of pipe you will have a ONE POUND PRESSURE DROP caused by frictional air loss.
Any turns in the pipe at fittings, ells, tees, and valves increase pressure drops even more.  That’s why the EQUIVALENT LENGTH OF PIPE (FT.) for PIPE FITTINGS chart was developed to help you determine the best pipe size for your system.

Are you planning to add more equipment in the next year or two?  Then plan for larger piping now.  Since the material costs in piping are low compared to installation or replacement cost, it’s wise to select pipe of an adequate size. If there is any doubt that a pipe size may create a pressure drop, use the next largest size. Remember that an oversize pipe compensates for possible scale build-up and provides for future expansion of the overall air system.

Steps to figuring what size piping your compressed air system needs:

  1. Determine your air compressor’s maximum CFM.
  2. Draw a piping schematic and show all pipe fittings, valves, etc.
  3. Measure and write the corresponding lengths of pipe on your schematic, then total the length of all straight pipes needed and note that on your schematic.
  4. Using TABLE 1, find your compressor’s CFM number on the far left column,
    and then go to the right until you see the column header with nearest length in feet to your total pipe length. Find where the CFM & PIPE LENGTH intersect on the chart and it will show the recommended pipe size for that length.
  5. Take that pipe size to TABLE 2 and use the table to find all the EQUIVELENT LENGTHS OF PIPE needed for each PIPE FITTING.  Write these lengths on your piping schematic at each fitting.
  6. TOTAL all the EQUIVELENT LENGTHS OF PIPE needed for each PIPE FITTING and add to your total of straight length of pipe.  This will give you a new and more accurate total pipe length needed.
  7.  Take your new total of EQUIVELENT LENGTH OF PIPE IN FEET back to TABLE 1 and use this number to determine the PIPE SIZE you need.
  8. Think of the FUTURE!
    Now is the time to plan for larger piping that may needed for additional future equipment.
How to figure the right air pipe size

Table 1- The right pipe size

Table 2 - to help figure the right air piping size

Table 2 - to help figure the right air piping size

Leaks can be a big source of wasted energy in an industrial compressed air system, sometimes wasting 20 to 30 percent of a compressor’s output. A typical plant that has not been well maintained will likely have a leak rate equal to 20 percent of total compressed air production capacity. On the other hand, proactive leak detection and repair can reduce leaks to less than 10 percent of compressor output.

In addition to being a source of wasted energy, leaks can also contribute to other operating losses.
Leaks cause a drop in system pressure, which can make air tools function less efficiently, adversely affecting production. In addition, by forcing the equipment to run longer, leaks shorten the life of almost all system equipment (including the compressor package itself).

Increased running time can also lead to additional maintenance requirements and increased unscheduled downtime. Finally, leaks can lead to adding unnecessary compressor capacity.

Q. Where do most leaks usually occur?

While leakage can come from any part of the system, the most common problem areas are:

• Couplings, hoses, tubes, and fittings

• Pressure regulators

• Open condensate traps and shut-off valves

• Pipe joints, disconnects, and thread sealants.

Q. How much can compressor leaks cost my business?

A small leak – no larger than 1/16″ can cost an extra $523 a year*.
Add a few other small leaks here and there until you have leaks equal to a 1/4″ opening…and now that “small leak” can cost you $8,382 a year.*  It is easy to see that what seems like a small leak comes with a very high price tag over time.

*Costs calculated using electricity rate of $0.05 per kilowatt-hour, assuming constant operation and an efficient compressor.

Q. How do you estimate the SIZE of AIR LEAKS?
It’s not very hard.  We’ll use the “TIME METHOD” to estimate percentage % of loss due to air leaks in your plant. 

1-    Turn OFF all air operated end-user equipment.
2-    Start your air compressor and let it cycle 3 times
3-    Time the OFF-LINE / UNLOAD TIME (not pumping time) using your watch. (Example: 5 minutes)|
4-   Time the ON-LINE / LOAD TIME (pumping time) using your watch. (Example: 2 minutes)
5-   Calculate total percentage of air leaks as follows:

Add the OFF / UNLOAD and the ON / LOAD times together:

Example: T(5 minutes)  +  T (2 minutes)= 7 minutes
Divide  ON / LOAD time T (2 minutes) by the total minutes: 2 ÷ 7 = 0.29

The result tells you 29% of your air compressor’s CFM’s are maintaining your AIR LEAKS.
This would mean that you are losing almost ONE THIRD of your compressed air to air leaks. 

Q. What’s the best way to detect and fix compressor leaks?

Since air leaks are almost impossible to see, other methods must be used to locate them.

The best way to detect leaks is to use an ultrasonic acoustic detector, which can recognize the high-frequency hissing sounds associated with air leaks. These portable units consist of directional microphones, amplifiers, and audio filters, and usually have either visual indicators or earphones to detect leaks.

A simpler method is to apply soapy water with a paint brush to suspect areas. Although reliable, this method can be time consuming.

Click here to see how to estimate the SIZE of AIR LEAKS.

Q. How To Fix Leaks

Leaks occur most often at joints and connections. 

Stopping leaks can be as simple as tightening a connection or as complex as replacing faulty equipment, such as couplings, fittings, pipe sections, hoses, joints, drains, and traps. In many cases, leaks are caused by failing to clean the threads or by bad or improperly applied thread sealant. Select high quality fittings, disconnects, hose, tubing, and install them properly with appropriate thread sealant.

Non-operating equipment can be an additional source of leaks. Equipment no longer in use should be isolated with a valve in the distribution system.

Another way to reduce leaks is to lower the air pressure of the system. The lower the pressure differential across an orifice or leak, the lower the rate of flow, so reduced system pressure will result in reduced leakage rates. Stabilizing the system header pressure at its lowest practical range will minimize the leakage rate for the system. Once leaks have been repaired, the compressor control system must be re-evaluated to realize the total savings potential.

Establishing a Leak Prevention Program

There are two basic types of leak repair programs:

1. The leak tag program
2. The seek and repair program.

The” seek and repair” method is the simplest. As it states, you simply find the leak and repair it immediately.

With the leak tag program, the leak is identified with a tag and logged for repair at a later time. This is often a two-part tag; one part stays on the leak and the other part is turned into the maintenance department, identifying the location, size, and description of the leak to be repaired. The best approach depends on the type, size, and the culture/work practices of the facility. It is more likely that the best solution will be a combination of the two.

*SOURCE:  Based on definitions taken from “Improving Compressed Air System Performance” published as a cooperative effort of the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) Best Practices and the Compressed Air Challenge®.


Tommy McGuire
Owner of McGuire Air Compressors
“Real People with Real Air Compressor Experience”

Offering you Quality Industrial Equipment at a Savings…





“What is the key to maintaining an efficient compressed air system?” The best reply would have to be — Preventive Maintenance.
According to “Wikipedia”: Preventive maintenance (PM) has the following meanings:
“The care and servicing by personnel for the purpose of maintaining equipment and facilities in satisfactory operating condition by providing for systematic inspection, detection, and correction of incipient failures either before they occur or before they develop into major defects. Maintenance, including tests, measurements, adjustments, and parts replacement, performed specifically to prevent faults from occurring.”

*Source: from Federal Standard 1037C and from MIL-STD-188 and from the Department of Defense Dictionary of Military and Associated Terms
Preventive maintenance activities include partial or complete overhauls at specified periods, oil changes, lubrication and so on. In addition, workers can record equipment information and deterioration so they know to replace or repair worn parts before they cause system failure.

The ideal preventive maintenance program would prevent all equipment failure before it occurs.

-Improves system reliability and helps keep equipment working and/or extend the life of the equipment.
-Decreases system downtime and actively helps prevent unbudgeted maintenance expenses from cropping up.
-Decreases the cost of having to replace equipment as often.
-Records operational data that can help you troubleshoot an emerging problem (called “Data Trending”)
Data trending is the recording of basic operation parameters including pressures, temperatures, and electrical data. For example, a slowly increasing temperature indicates a variety of maintenance requirements including cooler core cleaning, overloading of system and possible mechanical problems. Another example might include slowly decreasing pressure, indicating increased system flow requirements, reduced compressor performance or increased system leakage. Make sure someone is looking at this data on a regular basis. If the data is never reviewed then the benefit is lost.

To determine how valuable regular air compressor PM is to you and your business… you need to know what your “down-time” is worth. In some operations, down-time can cost hundreds, even thousands of dollars an hour.
There are many misconceptions about preventive maintenance…one being that it costs too much.

This line of thinking says regularly scheduled downtime for maintenance costs more than operating the equipment until repair is absolutely necessary…or until the equipment breaks. This may be true for some components, but don’t forget to consider the long-term benefits and savings associated with preventive maintenance that have been previously mentioned.

If regular Preventive Maintenance can help reduce unexpected downtime that results in loss of production, time and materials or the ruining of an expensive plant process–then it is well worth the investment. Not to mention that unscheduled shut-downs can be extended if the correct equipment parts or repair technicians are not readily available.

“How effective is your PM program?”
The answer is: “If your PM program isn’t finding problems, it isn’t effective.”

Corrective maintenance, usually called “repair”, is conducted to get equipment working again or fix any problems found during Preventive Maintenance.
The primary goal of maintenance is to avoid or reduce the consequences of failure of your compressed air equipment. PM is designed to preserve and restore equipment reliability by replacing worn components before they actually fail.

Key #3: ASSESSING YOUR EQUIPMENT: When to maintain and when to replace.
Here are several factors to consider when assessing your compressed air equipment:
-How critical is your compressed air equipment? If equipment fails, what is the impact on production or safety.
-What is the age & history of your equipment.
Equipment histories will prove that most failures occur during infancy (newly installed or recently overhauled) and old-age (self-explanatory).
How many times has this equipment failed in the past?
-How much do you trust this equipment to perform as designed when scheduled to run?
-Do you need newer technology on your equipment?
Assessing the answers to these questions will help you determine when your older equipment needs fixing or replacing. Preventive Maintenance will help your equipment last longer, run better, and save you loads of money in the long haul.

-Every piece of compressed air equipment should come with a set of MAINTENANCE INSTRUCTIONS and some type of operations& parts manual. Your operators should review the equipment information and keep it handy for future reference. If you purchased used equipment and don’t have the manuals, contact your equipment distributor for a copy.
– Follow the maintenance guidelines for your equipment.

The best thing you can do for your compressed air system is establishing a regular, well-organized maintenance program and strictly following it. Such a program is critical to maintaining the performance of a compressed air system and will save you time and money in the long haul. One person should be given the responsibility of ensuring that all maintenance is performed properly, on schedule, and is adequately documented.

Contact Us 1-888-229-9999

Owned and Operated by McGuire Air Compressors, Inc.
“Real People with Real Air Compressor Experience” 

Champion Advantage Air Compressor
Ask a Question:
What are the standard recommended minimum maintenance procedures for air-cooled reciprocating compressors? 


Routine Maintenance for Air-Cooled Reciprocating Compressors

Every 8 Hours (or Daily)
• Maintain lubricant level between high- and low-level marks on bayonet gauge. (Discoloration or a higher lubricant level reading may indicate the presence of condensed liquids). If lubricant is contaminated, drain and replace.
• Drain receiver tank, drop legs and traps in the distribution system.
• Give compressor an overall visual inspection and be sure safety guards are in place.
• Check for any unusual noise or vibration.
• Check lubricant pressure on pressure lubricated units. Maintain 18 to 20 psig when compressor is at operating pressure and temperature. High-pressure rated compressors should maintain 22 to 25 psig of lubricant pressure.
• Check for lubricant leaks.

Every 40 Hours (or Weekly)
• Be certain pressure relief valves are working.
• Clean the cooling surfaces of the intercooler and compressor.
• Check the compressor for air leaks.
• Check the compressed air distribution system for leaks.
• Inspect lubricant for contamination and change if necessary.
• Clean or replace the air intake filter. Check more often under humid or dusty conditions.

Every 160 Hours (or Monthly)
• Check belt tension.  

Every 500 Hours (or 3 Months)
• Change lubricant (more frequently in harsher environments).
• Check lubricant filter on pressure lubricated units (more frequently in harsher environments).
• Torque pulley-clamp screws or jam-nut.  

Every 1,000 Hours (or 6 Months)
• When synthetic lubricant is used, lubricant change intervals may be extended to every 1,000 hours or every 6 months, whichever occurs first (change more frequently in harsher conditions).
• Inspect compressor valves for leakage and/or carbon build-up. The lubricant sump strainer screen inside the crankcase of pressure-lubricated models should be thoroughly cleaned with a safety solvent during every lubricant change. If excessive sludge build-up exists inside the crankcase, clean the inside of the crankcase as well as the screen. Never use a flammable or toxic solvent for cleaning. Always use a safety solvent and follow the directions provided.  

Every 2,000 Hours (or 12 Months)
• Inspect the pressure switch diaphragm and contacts.
Inspect the contact points in the motor starter. 

Compressors may be shipped without lubricant in the crankcase. Before starting the compressor, add enough lubricant to the crankcase to register between the high and low marks on the dipstick or on bull’s eye sight gauge. Use the specified lubricant or consult the manufacturer for recommendations.
 Certain synthetic lubricants have proven under extensive testing to minimize friction and wear, limit lubricant carryover, and reduce carbon and varnish deposits. They will support the performance characteristics and life and are highly recommended. Refer to the manufacturer’s specifications to determine the correct amount of lubricant and viscosity to use for your model and application. Use the supplier’s lubricant analysis program.

For your next order of Compressor Lubricants and Filters – call 1-888-229-9999…

Or click here for SERVICE KITS and Lubricants for your compressor.

*SOURCE: Improving Compressed Air System Performance: A Sourcebook for Industry is a cooperative effort of the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) Best Practices and the Compressed Air Challenge®.