Plant Air Systems – What You Need to Know to Save Money
The design of your plant air system could be wasting energy and money. Learn a few key design tips that makes all the difference.
By K. G. Sims
Date Posted: 10/1/2011
If your plant is like many manufacturing plants around the country, your air system may be extremely inefficient forcing your air compressors to work harder, wasting energy and money in the process. Think your system is fine? Well, mmm…… maybe not.
Some systems are only about 70% efficient with the air that is being generated. Why is this poor design such a common problem? One of the biggest causes is a lack of knowledge. Very few suppliers of air compressors have a trained field personnel to advise you on piping for the most efficient operations. If they did, many systems in pallet plants would be more efficient.
It is a sad day in the life of a pallet factory owner when he spends thousands of hard-earned dollars for a new compressor, dryer, and baffle or storage capacity, only to discover that he only marginally improved his air situation. The gains he was promised are never realized because of the piping arrangement of the plant.
How does this happen? Most plants are works-in-progress; or they are always in some mode of adjustment or expansion. Without advice or instruction, most plants build branch-type air piping systems. This means they run single lines out from the compressor room and branch off to each needed location. The problem with this system is that air is being pumped in only one direction creating dead-ends at the end of the piping. If they had been properly advised, they would have “closed the loop” and returned the main trunk air piping back to the original line coming from the compressor room.
With air being supplied bi-directionally, you would no longer have the severe pressure and air volume drops associated with non-closed loop systems. How does this all work? Air flowing in one direction cannot flow easily 90-degrees down into the branch pipe that goes down to your nailing machine or station. Air does not act like water in a piping system. It is not as easily affected by gravity. Thus, the flow downward is strained because the demand of air from your equipment causes turbulence at the entrance of the downward pipe. This occurs as the air tries to flow over the opening in the direction of least resistance.
When a closed loop system is employed, air flow is more like water and the air “flushes downward” into the branch piping.
This turbulence, and the resulting pressure and volume drop, leads to inefficiencies. It can cause you to run your compressor head pressure up to 140 psi in an attempt to maintain 90 psi out toward the end of the branch system. In the same situation with a closed loop system, the pressure drop may only be 10 psi. And where there is adequate pressure, you may still lose volume quickly in a branch system. If your nailers are “stair-stepping” nails; meaning they drive the first one or two then begin to leave them up higher and higher, then the tool is not recovering adequate air volume to refill and cycle quickly. Thus, you either slow your nailing down or use a hammer to drive the nails in, neither of which is an attractive option.
Looking at plant layout details like this can make all the difference as energy costs continue to rise. Taking a good look at your air system is a first step to see if you are losing efficiency due to the piping arrangement. Also look at how close together your drops from the main trunk piping are. It is recommended that you keep a distance of 10’ between drops. Poor air flow costs you money because the more that compressor has to run, the more it costs. It is also advisable to have someone patrol the plant after shift end, once per week, listening for leaks. A small leak may not seem like much. However, if you are on the edge of your capacity, that small leak may be causing your compressor to cycle on and off one or two additional times per day. These frequently missed problems can add up quickly when it comes to your plant costs.
Mid Continent Nail Corp. trains its field sales and service personnel to assist customers in reviewing their air systems when requested. Frequently, Mid Continent personnel spot piping or equipment arrangement issues that cost customers money. When considering expansion or equipment replacement in your air system, it is generally best to have potential suppliers provide you with a free air system audit to evaluate all of the components of your air system. This will require them to bring in one of their trained professional staff. Even if you are not planning anything new or an expansion, it is a good idea to have a trained professional from the equipment supplier or an engineering firm come in and evaluate your system. The only thing you have to lose is cost.
K.G. Sims is the manager of industrial sales and pneumatics at Mid Continent Nail Corp. He can be reached via email at email@example.com or by calling cell: 573/778-7787, office: 800/867-6245.
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