(AS AT 31 st MARCH, 2002)

Transcription

1 ACACA PROTOCOL 2000 (AS AT 31 st MARCH, 2002) ACACA PROTOCOL 2000 INCLUDES (A) CODE OF PRACTICE FOR MANUFACTURERS AND/OR SUPPLIERS OF COMMERCIAL AIR COMPRESSORS AND METHOD FOR DETERMINING (B) RECIPROCATING AIR COMPRESSOR PUMP DISPLACEMENT (C) FREE AIR DELIVERY OF AN AIR COMPRESSOR PACKAGE WITH A PUMP DISPLACEMENT OF UP TO 600 LITRE/MINUTE AND (D) TEST REPORT. Table of Contents A. Code of Practice Page 2 B. Pump Displacement Page 2 C.Free Air Delivery (FAD) of Air Compressor Page 3 (i) Pump Up Test (Simplified Method) Page 3 (ii) General Pump Up Formula Page 4 (iii) Specific ACACA Pump Up Test Method Page 4 (iv) Calculation of FAD Page 4 (v) Protocol 2000 FAD Standard Testing Procedure Page 5 D. Test Report Record Page 7

2 2 A. CODE OF PRACTICE Members of the Australian Commercial Air Compressor Association agree to : i) Actively promote the aims and objectives of ACACA in the market, and to other suppliers in the industry. ii) iii) iv) To manufacture and/or supply air compressors which are safe to use and which comply with both Federal and State Government regulations in respect of workplace, electrical and pressure vessel safety and the Electromagnetic Compatibility (EMC) Scheme. Where regulations so require, to apply the relevant Australian Standard or equivalent International Standard to components used in the air compressor package such as motor, pump, air receiver tank etc. Act in accordance with ACACA Protocol 2000 when calculating the pump displacement and free air delivery ratings of each air compressor package. v) To affix the approved ACACA Protocol 2000 label on each and every air compressor package sold by them. a) Each ACACA label shall show both Pump Displacement (PD) and Free Air Delivery (FAD) b) each member may choose to show PD and FAD in litres/min or CFM but not both. That is, if PD is shown in litres/min then FAD also shall be shown in litres/min. vi) To encourage other manufacturers, assemblers, and importers to join ACACA and to adopt ACACA Protocol B. PUMP DISPLACEMENT Displacement is the theoretical volume of air that can be pumped by a reciprocating air compressor, if it was 100% efficient. The four critical parameters that must be known for calculating displacement are: 1. Cylinder Bore Diameter measured in mm 2. Cylinder Bore Area [= π (Bore diameter)_ ] 4 3. Length of piston movement (Stroke) measured in mm 4. Number of pistons or cylinders 5. Rotational speed of pump shaft which shall be determined by the speed of rotation (rpm) of the pump shaft under load when the air receiver is showing a pressure of 700 kpa (7 Bar). The shaft speed shall be measured by means of a standard tachometer with an accuracy of ± 0.5% or better. Formula for calculating Pump Displacement (PD): The calculation requires the area of the cylinder bore to be multiplied by the piston stroke, this give cylinder volume or capacity. This is then multiplied by the number of cylinders and then multiplied by the rotational speed of the pump shaft.

3 3 PD(litres/min) = Bore Area (mm_) x Stroke (mm) x No. of cylinders x pump speed (rpm) 1,000,000. Conversion Factors a) π = b) To convert litres/min to litres/sec divide by 60. c) To convert litres/min to cubic feet/min (cfm) divide by Example To calculate the displacement of a pump of the following dimensions: Bore diameter (d) = 2 π.d 60mm (Bore Area = ) 4 Stroke length = 40mm Speed of pump shaft = 933rpm as measured by a tachometer Number of cylinders = 2 Then PD (litres/min) = Bore Area (mm_) x Stroke (mm) x No. of cylinders x pump speed (rpm) 1,000,000 60x60 = [(3.142x ) x40x2x933] 1,000, = 211 litres/min (rounded to nearest litre) PD (cfm) = = 7.5 cfm (rounded to nearest 0.1) C. FREE AIR DELIVERY (FAD) OF AIR COMPRESSOR PACKAGE a) FAD is the volume flow rate of air (measured at ambient pressure and temperature and humidity) which has been compressed and delivered to the terminal discharge point of the air compressor package. It is a measure of the volume of air available for use at the exit point of the air compressor package. b) Pump Up Test (Simplified Method) i) The pump up test consists of operating a compressor at a constant speed and observing the time required to increase the pressure in the air receiver (tank of measured volume) from 600 kpa(g) to 800 kpa(g) ie when the compressor is operating under load. The approximate air output of the compressor or FAD can then be calculated. The pump-up test is a simplified method of estimating Free Air Delivery. Normal Variations in ambient temperature, atmospheric pressure and relative humidity are ignored so the results are indicative only and cannot be taken as authoritative. However the pump up test is a useful comparative measure and has been selected as being suitable to rate commercial air compressors for Pump Displacements up to 600 litre/min. Larger compressors will continue to be rated in accordance with ISO 1217.

4 4 ii) General Pump Up Formula To estimate the average free air delivered by the compressor during the pump up pressure change the following formula may be used. The result disregards temperature differences and changes throughout the system Where V ( P2 P1 ) FAD = P. T 0 FAD is the average volume of air delivered by the compressor during the pump up pressure change. V P0 P1 P2 T is air receiver volume is atmospheric pressure is air receiver pressure at commencement of test is air receiver pressure at end of test is the pump up time taken to increase the pressure in the air receiver from P1 to P2 And where P0 P1 and P2 are expressed in absolute units. iii) Specific ACACA Pump Up Test Method FAD shall be based on the average pump up time for the gauge pressure in the air receiver to increase from 600 kpa to 800 kpa (or 6 Bar to 8 Bar). This recognises that as the pressure builds from zero the pump efficiency decreases. The test to determine Pump Up Time shall be carried out indoors under normal operating conditions which have been defined as ambient conditions where:. Room temperature is in the range 15ºC 30ºC. Atmospheric Pressure is that between sea level and 300 metres. Relative humidity is between 50% and 85%. These conditions have been taken to approximate the compressor package performance when in normal use. Actual FAD may vary from the stated FAD by up to an estimated 5% when the air compressor is operated at the extremes of the above ambient conditions. Testing shall be carried out strictly in accordance with Protocol 2000 FAD Standard Test Procedure refer (v) below. (iv) Calculation of FAD Using the general formula (refer (ii) above) V ( P2 P1 ) FAD = P. T 0

5 5 P2 P1 = 800 kpa 600 kpa = 200 kpa (2 Bar) P0 Then FAD = 1 Bar (100 kpa) 2V = T V The air receiver capacity in litres. This must be verified by filling the air receiver with water and measuring the volume of water in litres, to the nearest 0.2 litre. T The average time in minutes and decimals of a minute, for the pressure of air in the receiver to increase from 600 kpa to 800 kpa. The average time shall be taken as the mean of three time rest results. FAD The Free Air Delivery is then calculated by dividing twice the capacity of the air receiver by the pump up time (measured in minutes and decimals of a minute) taken for the pressure in the air receiver to ncrease from 600 kpa to 800 kpa (6 Bar to 8 Bar). FAD (litres/minute) = 2V (twice the volume of receiver - litres) T (time in minutes to pump up from 600kPa to 800kPa) Example V = 54 litres T = 25 sec = minutes Then FAD = 2 x = 259 litres/min (9.15 CFM) To convert from litres/min to CFM divide by 28.3 (v) Protocol FAD Standard Testing Procedure Testing Free Air Delivery of an Air Compressor Package using ACACA Pressure Timing Instrument (Test Box) Step 1 - Preliminary Requirements a) Measure the volume of the air receiver tank by filling the air receiver with water and measuring the volume in litres or cubic feet to an accuracy of ± 0.4%. For example, for a nominal 50 litre air receiver tank measure its volume to the nearest 200ml. b) Ensure stable 240 volt supply to compressor package under test. If voltage varies it may affect RPM of compressor pump and therefore affect accuracy of the test. Step 2 Connect Test Box Connect Test Box to (a) outlet valve of compressor package using no more than 1 metre of 6 mm O.D. nylon tube. (b) Plug in Test Box to 240 volt supply.

6 6 Step 3 Warm up to operating temperature Operate compressor for between 5-10 minutes under a load of 700 kpa to ensure that the compressor has reached normal operating temperature before starting the test. Turn compressor off, drain air and condensate completely from Air Receiver, Close air bleed valve and press re-set button on Test Box. Step 4 Time Tests (must be carried out whilst air compressor unit is at operating temperature a) With compressor at operating temperature and air receiver empty start compressor pumping b) Timer will activate when pressure reaches 600 kpa and stop when compressor reaches 800 kpa. c) Read off time and record it. Record time to nearest 0.01 second. d) Press reset button to zero timer for next test. e) IMPORTANT: bleed all pressure in unit back to zero kpa. If pressure is not bled back to zero the timer WILL NOT ACTIVATE on your next test. Red OUT1 LED must be off for the next test to proceed. f) Do not remove connection tube between compressor and test box until all testing for unit is completed. Drain residual air via another port (bleed valve). g) Repeat procedure 3 times and record the test results on ACACA Protocol 2000 Test Report. h) Testing must be completed within twenty minutes after the Compressor has reached normal operating temperature. i) After the results of 3 tests have been recorded, take the average and calculate FAD of compressor package in accordance with the ACACA Protocol 2000 formula. j) Round the results as follows:- i) CFM should be rounded to the nearest 0.1 CFM eg to under 9.2 should be rounded up to 9.2, and between 9.10 and below 9.15 would be rounded down to 9.1 CFM. ii) litres/min should be rounded to the nearest litre eg litres/min to under 283 is rounded up to 283, and between and below is rounded down to 282 litres/min. Step 5 - Recording After test is completed record on the Test Report information regarding this particular model ie: Model No. Serial No, Speed of Pump, Horsepower of Motor, Volume of Tank, Displacement of Pump, Free Air Delivery figure. Retain Test Report for future reference. Note: ACACA Protocol 2000 relates to Pump Displacement and Free Air Delivery as measured in accordance with the above procedures. ACACA Protocol 2000 does not imply approval of or performance guarantee of an air compressor unit, or the individual components of that air compressor unit. Refer to manufacturers warranty conditions.