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Airometrix LP Flow Meter Choose A topic you would like to Learn more about:
The LP meter is based on the principle of using multiple orifices of different sizes and known flow rates to quantify the air flow from a compressor. By opening valves to allow known flows to escape to atmosphere, the LP meter acts as a load bank for the compressor. To test, isolate an air compressor from the system. Plumb the flow meter so the full flow of compressed air goes to the meter. Open valves on the meter to allow known quantities of compressed air to escape to atmosphere through the precision machined orifices. Open valves until the compressor can just barely keep up at the selected test pressure and add the valves that are open. This is the Free Air Delivered (FAD) for the compressor at that pressure. By testing at various pressures, a performance curve for the compressor can be built in a matter of minutes. Simultaneous power measurements give a complete picture of compressor operation. System leak volume and consumption can also be determined once the compressor performance has been established. For more information, see our How to Test Page. Compressed air is the most expensive utility most industrial facilities have. It is twice the cost of hydraulic power and 8-10 times the cost of direct electrical power and it is widely used and readily wasted. Compressed air waste is tolerated mainly because it does not make a mess, is odorless, tasteless, and in many cases the waste is very difficult to find and quantify. Many devices are now available to help diagnose aspects of compressed air systems including ultrasonics for leak detection, in-line flow meters for flow monitoring, and pressure profiling for system response. Yet, none of these devices can quantify air leaks, determine system performance, or allow diagnosis of compressor controls under load. These are the parameters which are needed to properly quantify energy savings and minimize operational costs. At an electrical rate of $0.06/kWh, the cost to operate a 25hp compressor (~100cfm) is $10,000 per year based on a three shift operation. A 250hp compressor (~1000cfm) would cost $100,000 per year to operate. These costs do not include water, maintenance, and other operational costs. This is likely as much as twice the original cost of the compressor that is being paid out on an annual basis. Many facilities can easily save 20% of their compressor costs with low-cost/no-cost (non-capital) projects with payback under one year. Savings from 20-50% or more can usually be achieved in a more comprehensive approach. More than 1600 compressors in over 400 plants have been testing using the LP flow meters and the average facility is usually found to have between 20-40% of their system volume feeding leaks.Some have been greater than 60%. reducing these leaks to an acceptable 10-15% can save tens of thousands of dollars per year. Compressor performance and controls are areas which are often overlooked or inadequately addressed in a typical system analysis or audit. Pump up tests or load/unload tests are used to match operating points to a manufacturer's curve and the controls and compressor performance are assumed to meet with the specifications as installed. Many times the power consumption is used as the gauge of compressor performance with no actual flow measurements taken. This can lead an auditor astray since problems with the controls, loading characteristics, or output are not being measured. Any deficiencies in the compressor room will be blamed on the system since there is no way of checking the compressor's true performance. Inappropriate or unnecessary recommendations may be made which will eventually cost the facility more and may or may not cure the problem. Controls for inlet throttling and blowoff are often found to be set inappropriately or malfunctioning even when set by a factory authorized technician or when set following strict guidelines set out by the OEM. This is prevalent in both dynamic and positive displacement type compressors. During a period of testing in British Columbia, when over 230 plants were tested, over 80% of the rotary screw compressors featuring modulating air inlet controls were found to produce 3.5 to 3.8 cfm/hp at 100psig instead of the the rated 4.0to 4.25cfm/hp. This is not necessary a flaw of the controls, it is rather a problem of detection and diagnosis. The fix is usually simple (maintenance or replacement of the diaphragm valve) at less than $100 per compressor. With the LP meter, this and other problems can be diagnosed in a matter of minutes. The LP Flow Meter is a tool you can use to make informed decision regarding the operation of your compressed air system. You don't send your electrician out without an amp and volt meter, why shouldn't you have the same basic tool to diagnose your air system. These meters are of greatest benefit to a facility with 50 hp or more of on-line compressor capacity. In areas where electrical costs are high ($0.09 per kWh or more) smaller systems may benefit as well. The main applications for the Flow meters are in industrial settings and other facilities with specialized compressed air needs such as hospitals and Universities. The LP flow meter is used to diagnose air compressor output and controls functions as well as optimize timing of maintenance and overhauls. Facilities and maintenance professionals as well as those who have direct responsibility over compressor operations can benefit directly by having real operating data upon which to base their decisions. Production and engineering professionals can use the consumption information to better determine their air needs within the facility and assess need for expansion or replacement of equipment. Management can benefit by quantifying costs associated with this often overlooked utility.
All meters measure from zero to the maximum rated cfm in 10cfm increments. Options include: wheel mounted for portability, metric ratings, electronic pressure gauge, and storage/travel cases. Standard flow meters are rated for flows between 50psig and 150psig. Flow applications up to 500psig or flows greater than 10,000cfm can be accommodated.
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