The LP Meter

If your plant utilizes steam, hydraulic or compressed air energy sources for production, there is no question that compressed air power is the most expensive to produce. Plant maintenance staff will not tolerate hydraulic fluid leaks, while they often overlook air leaks simply because air is invisible. Air leaks and compressor inefficiency cost industries millions annually. The LP mechanical compressed air flow meter will enable you to get a firm handle on this valuable loss by allowing you to measure air leaks and assess compressor performance. Easy to install and operate, it takes minutes to perform a compressor capacity test, air leak test or production consumption test and all within 2% accuracy. Some industrial plants that have incorporated the LP meter are saving thousands of dollars annually through improved air leak maintenance and knowing when to adjust or repair malfunctioning compressors. The LP range of flow meters cover flows from 10 to 3400 cfm & more.

The LP range of meters has a successful history in British Columbia Canada, where BC Hydro, through the Power Smart program has supported the LP Meter to customers. Over 350 meters have been installed in BC, Quebec and Ontario Canada and are continuing to provide end users with substantial savings in the area of compressed air.

See what an LP meter has done for a denim manufacturer or a paper mill.

The flow meter operates on the principle of a plurality of precision machined orifice plugs. It holds true that if you precision machine a hole or orifice to an exact size and profile, and polish it, the amount of compressed air which will escape out of that hole to atmosphere can be predetermined with a considerable degree of accuracy. Since these parameters never change, one can expect the same results from year to year. Since there is no programming to perform, no batteries to change or go dead, the LP range of meters show benefits over other devices like the pitot tube or orifice plate with pressure taps and electronic transmitter type flow measuring devices.

EXAMPLE :The LP07 model (Capacity of 1600 CFM) is fitted with a 100, 200, 400 and 800 CFM orifice plugs. in addition it also has 4 smaller orifices of 10, 15, 25 and 50 CFM for fine tuning the flow measurement.

It is therefore possible to test flows between 10 CFM and 1600 CFM (FAD) at 100 psig pressure. Although almost all industrial compressors are rated to deliver full output at 100 psig pressure, there will be times when you may have to perform the test at some pressure lower than 100 psig because the compressor, for whatever reason, may not be able to develop its full rated pressure. Since the orifices are precision machined to allow a definite amount of air flow at 100 psig, when performing a test below 100 psig, for every 1 psig below 100, derate the orifice flow by 1%, for every 1 psig above 100, increase the orifice flow by 1%.

EXAMPLE : You are testing a 200 HP compressor and you have 1000 CFM of orifice capacity open with the compressor running flat out at 95 psig. The correct flow will be 1000 x 95% = 950 CFM at 95 psig pressure.

1. Close plant shut off valve (between the receiver and the plant) Operate compressor flat out by dumping whatever amount of air is necessary to maintain a steady 98-100 psig on the LP meter calibrated pressure gauge. Add the orifice designations that are open and this is true compressor air delivery.(TEST # 1) (For best accuracy perform test at 100 psig.)

2. Next, open plant shut off valve (between the receiver and the plant) and allow a few minutes to charge the plant system to full pressure. Repeat the test as described in step 1, except the compressor must now satisfy air leaks so that you will be dumping less air when maintaining a steady 98 - 100 psig.

3. Subtract the amount (CFM orifice designations ) you dumped on the second test (TEST # 2) from the first test (TEST # 1) and the difference is plant air leaks.(TEST # 2)

4. All this takes about 15 minutes in an average production plant. The results can be quite accurate if properly carried out. Both tests should be performed at the same pressure.

5. Testing can only be performed when plant production is down, ie.. weekends, maintenance shutdown, shift changes, lunch breaks etc...

6. If your system is fitted with a proper aftercooler and moisture drain, the result will represent the true air flow entering your plant and often referred to as CFM of FAD*. (* Cubic feet per minute of free air delivery) This is the proper way to rate compressors.

First, test compressor(s), which would normally be operating to satisfy production needs, for maximum delivery output at 98 - 100 psig. (This test would be done during off shift.) It now becomes a simple matter to determine how much air is actually used to satisfy production needs.

Once production goes on stream, get to the controls of the LP meter and drain off (by opening individual orifices) whatever amount of air it takes for the compressor(s) to be operating flat out and to be holding a steady 98 -100 psig on the calibrated LP pressure gauge. Next, add up the orifice designations open, subtract that amount from the true compressor air delivery test (TEST # 1) and subtract also the amount taken from the plant air leak test (TEST # 2). The remaining difference is the production consumption. (TEST # 3)

For pricing information on the LP range of products contact:

Impact RM

Click HERE to submit a form to Impact RM so that we can tell you how much money you can save and what your return on investment will be.

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