Chapter 17 Operation Instruction of Soap Bubble Meter

Transcription

1 Chapter 17 Operation Instruction of Soap Bubble Meter PRINCIPLE OF OPERATION The APM 520A Flow Calibrator is designed for use as a primary standard for calibrating flow meter in the low or medium flow range. For determining the flow-rate, the traveling time of the soap film through a fixed volume marked on the glass tube is determined by the calibrated stopwatch. Figure.1 shows a typical set-up interconnecting the soap-film calibrator, flow meter under test and the Suction pump needed to cause airflow through the system. Note that air enters the calibrator at atmospheric pressure and only a soap-film and short tubing separate the Rotameter from the calibrator. As such the flow meter and calibrator operate at virtually the same pressure and temperature, no pressure and temperature correction is needed. The glass-tube provides a fixed volume with inert material that remains stable over the operating life of the calibrator. Record the s and calculate the flow rate:- Flow rate (LPM) = Volume Between two fixed point (Litres) x 60. Time taken by film to travel between fixed points (Seconds) 115

2 Envirotech APM 520 Flow Calibrator The Envirotech APM 520 Flow Calibrator is designed to provide a reliable and portable flow standard for flow verification of environmental sampling systems. The APM 520 is a primary flow calibrator based on a standard glass body soap bubble meter. A portable vacuum pump is provided to motion through a fixed volume and a calibrated watch is also provided to read the traveling time of soap film through a fixed volume. Each APM 520 calibrator is calibrated using a standard volume traceable to NPL maintained at Envirotech. Features Primary Standard based on Soap bubble meter. Dimensional & timing accuracy traceable to national standards. Suitable for verifying rotameters used in air monitoring systems. Specifications Flow Range : 500 ml/min to 3 Liters/min Accuracy : + 2% Operating Model : Single cycle with manual restart Temp. range : 5-50º C Humidity range : 0-70% non-condensing Power req. : 220 Volts AC single-phase AC mains. Warranty : 1 Year Optional Accessories Rotary Vane type pump with 3lpm free air displacement for providing suction pressure. For prices and clarifications contact: Envirotech Instruments Pvt. Ltd. A-271, Okhla Industrial Area Phase-1 New Delhi Ph , Fax

3 1.0 System Configuration The soap bubble meter Envirotech APM 520 Calibrator consists of three units: - 1. Glass Tube: This unit provides the fixed volume through which air is displaced. As it is made of glass the volume does not vary with temperature and age of the instrument. 2. Suction Pump: This unit provides the suction for air displacement through the glass tube. It is portable and 220V mains operated pump. 3. Stop Watch: It is portable and battery operated it gives reading in min: sec: milliseconds. 2.0 Operation Procedure Following steps are to be used for the operation:- 1. Switch on the pump unit. 2. Generate a few films by closing the lower opening of glass tube using figure and passing them through the tube to moisten the inner surface of the tube. 3. Now set the flow rate on a Rotameter at the value you wish to check. 4. Generate a clear film and record the traveling time through the fixed volume of glass tube using the stopwatch. 5. Take 2-3 readings at different flow rates on a Rotameter and calculate flow reading and record average flow rate. Some time, if the glass tube inner surface is dry a soap film may get ruptured midway through its travel path. Repeat the steps again after stopping stop watch Attn: - If the system repeatedly fails to generate a soap-film or if multiple films are being formed check the soap solution level in the bottom portion of the glass tube. Frequent misses in generations of film indicates the level should be topped up while formation of multiple films can be corrected by removing some liquid from the system. Format for Data recording enclosed in following page 117

4 3.0 Precautions The APM 520 calibrator is a sensitive instrument designed for precise measurements therefore its operation and handling must be done very carefully. Points given below must be always in mind while using the equipment. 1. System contains a fragile glass part so it must be handled carefully or it may be damaged. 2. Never run the pump unit freely continuously for more than 2hrs. 3. Keep the stopwatch away from high temperature. 4. Test Piece Rotameter should be clean and dry; rotor should be move freely in side the rotameter tube. 5. Vibrations must not be present at the system while in use. So putting the system on firm structure and horizontal surface is recommended. 6. While you are making air flow connections no sharp bends to be present in the piping. Also avoid long pipes. 7. While you are filling soap solution in equipment or before use it must be filled up to an appropriate level. 8. Only qualified professionals must attempt service of this instrument. 9. Recalibration of the system recommended after every one year of use. 118

5 Calibration Test Data Sheet for Flow Meter Instrument Name & Sl. No.: - Rotameter No.: - Rotameter (lpm) Time Taken in Sec. for passing 500 cc air in soap bubble tube 1 st 2 nd 1 st Actual Flow Rate (lpm) 2 nd Average (lpm) Calibration on Factor Tube Flow/ Test Piece (Calibrated by) 119

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