Removing Condensation Is Key To Maintaining Performance

When air is compressed, it is heated to a point that causes the water or moisture  to turn to vapor. As the air begins to cool, the vapors turn to condensation, which can cause performance issues in a compressed air system. Many times this condensation forms in the basic components in the system like a receiver tank, dryer or filter.

Condensation is formed from water vapor in the air

It’s important to remove this condensation from the system before it causes any issues. There are four basic types of condensate drains that can be used to limit or prevent loss of air in the system.

The first method would be to have an operator manually drain the condensation through a drain port or valve. This is the least reliable method though as now it’s the operator’s responsibility to make sure they close the valve so the system doesn’t allow any air to escape which can lead to pressure drops and poor end-use device performance.

Example of a float drain

Secondly, a float or inverted bucket trap system can be used in plants with regular monitoring and maintenance programs in place to ensure proper performance.. These types of drain traps typically require a higher level of maintenance and have the potential to lose air if not operating properly.

An electrically actuated drain valve can be used to automatically drain the condensate at a preset time or interval. Typically these incorporate a solenoid valve  or motorized ball valve with some type of timing control.  These types of systems can be unreliable though as the valve may open without any moisture being present in the line, which can result in air loss or it may not be actuated open long enough for acceptable drain off. With these types of drains, it’s best to use some type of strainer to remove any particulate that could cause adverse performance.

Lastly,  zero air-loss traps utilize a reservoir and a float or level sensor to drain the condensate and maintain a satisfactory level. This type of setup is very reliable but does require the reservoir be drained frequently to keep the system clean and free of debris or contaminants.

If you have any questions or would like to discuss a particular process, contact an application engineer for assistance.

Justin Nicholl
Application Engineer
justinnicholl@exair.com
@EXAIR_JN

 

Condensation image courtesy of Anders Sandberg via creative commons license

Float drain image courtesy of the Compressed Air Challenge

Estimating the Cost of Compressed Air Systems Leaks

Leaks in a compressed air system can waste thousands of dollars of electricity per year. In fact, in many plants, the leakage can account for up to 30% of the total operational cost of the compressor. Some of the most common areas where you might find a leak would be at connection joints like valves, unions, couplings, fittings, etc. This not only wastes energy but it can also cause the compressed air system to lose pressure which reduces the end use product’s performance, like an air operated actuator being unable to close a valve, for instance.

One way to estimate how much leakage a system has is to turn off all of the point-of-use devices / pneumatic tools, then start the compressor and record the average time it takes for the compressor to cycle on and off. The total percentage of leakage can be calculated as follows:

Percentage = [(T x 100) / (T + t)]

T = on time in minutes
t = off time in minutes

The percentage of compressor capacity that is lost should be under 10% for a system that is properly maintained.

Another method to calculate the amount of leakage in a system is by using a downstream pressure gauge from a receiver tank. You would need to know the total volume in the system at this point though to accurately estimate the leakage. As the compressor starts to cycle on,  you want to allow the system to reach the nominal operating pressure for the process and record the length of time it takes for the pressure to drop to a lower level. As stated above, any leakage more than 10% shows that improvements could be made in the system.

Formula:

(V x (P1 – P2) / T x 14.7) x 1.25

V= Volumetric Flow (CFM)
P1 = Operating Pressure (PSIG)
P2 =  Lower Pressure (PSIG)
T = Time (minutes)
14.7 = Atmospheric Pressure
1.25 = correction factor to figure the amount of leakage as the pressure drops in the system

Now that we’ve covered how to estimate the amount of leakage there might be in a system, we can now look at the cost of a leak. For this example, we will consider a leak point to be the equivalent to a 1/16″ diameter hole.

A 1/16″ diameter hole is going to flow close to 3.8 SCFM @ 80 PSIG supply pressure. An industrial sized air compressor uses about 1 horsepower of energy to make roughly 4 SCFM of compressed air. Many plants know their actual energy costs but if not, a reasonable average to use is $0.25/1,000 SCF generated.

Calculation :

3.8 SCFM (consumed) x 60 minutes x $ 0.25 divided by 1,000 SCF

= $ 0.06 per hour
= $ 0.48 per 8 hour work shift
= $ 2.40 per 5-day work week
= $ 124.80 per year (based on 52 weeks)

As you can see, that’s a lot of money and energy being lost to just one small leak. More than likely, this wouldn’t be the only leak in the system so it wouldn’t take long for the cost to quickly add up for several leaks of this size.

If you’d like to discuss how EXAIR products can help identify and locate costly leaks in your compressed air system, please contact one of our application engineers at 800-903-9247.

Justin Nicholl
Application Engineer
justinnicholl@exair.com
@EXAIR_JN

 

 

 

 

 

Super Air Knife = Super Blow Off

Super Air Knife Blow Off

Earlier this morning I had the opportunity to guide an end user through the use of our Super Air Knife.

We began the discussion surrounding a blow off need during machining of a 5/8″ blind hole.  The end user needed a strong, consistent air flow to remove debris over a variable surface area.  We considered using Super Air Nozzles, but the variable location of the blind hole at different times in the process proved to warrant this solution impractical.

We arrived back to the original idea of using a Super Air Knife to blow out the blind holes.  To be sure we had the same conceptual view of the application, the engineer with whom I spoke sent a component photo (above).  One of the notes we made about the setup above was to increase the distance between the armature and the Super Air Knife, just a bit.  We generally advise to provide at least 3-6” of space between the Super Air Knife and the surface/material to be blown off because this allows the Super Air Knife to entrain more surrounding air.  Referencing the actuator on the left side of the drawing, it was decided to raise the armature to allow for this spacing.

This setup will be repeated on the opposite side of the machine to ensure satisfactory quality of the parts being made.  We also went on to discuss the Electronic Flow Controller and the possibilities of controlling the Super Air Knives through already installed PLCs (we are fond of both, for efficiency purposes).

This application was an excellent example of the versatility of a Super Air Knife.  If you have an application question or related need, contact an EXAIR Application Engineer.

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE