Opman AVG2 v09.qxd - Fieldpiece Instruments
Contents
1. to 200 microns in a couple of minutes If you are unable to draw the vacuum down to these levels check for leaks and or thoroughly clean the well of the sensor with isopropyl rubbing alcohol How it works Power is delivered to a thermistor which is exposed to the vacuum being tested Molecules from the gas conduct heat from the thermistor The fewer gas molecules there are the less heat is taken away The power to the resistor is adjusted to keep the temperature of the thermistor within a nar row range The lower the power required by the resistor the lower the pressure The power deliv ered to the thermistor is measured and scaled to pressure It is very important that the thermistor sensor be kept clean and free of oil to enable unim peded flow of heat from the thermistor LED Indicators INC When the pressure is increasing the LED will blink at a rate relative to the rate of pressure increase DEC When the pressure is decreasing the LED will blink at a rate relative to the rate of pressure decrease STABLE When the rate of change of pressure is zero the LED will light ON When the AVG2 is on the LED will light LO BAT When the batteries need replacement the LED will light Cleaning the sensor Drip isopropyl rubbing alcohol into the opening of the sensor and pour it out flushing any contami nants along with it Leave the sensor opening uncovered long enough to completely evaporate any leftover alcohol D2. Vacuum Gauge Accessory Head Model AVG2 VAA Fieldpiece aver _ VAA Fieldpi ce LEO NLL OPERATOR S MANUAL Specifications Sensor Precision thermistor Fitting Standard 1 4 flared brass fitting male Conversion rate 1 mVDC 1 micron of mercury Range 50 to 2000 microns of mercury Resolution 1 micron of mercury Accuracy 10 or 10 microns 50 to 1000 microns 73 F 9 F 23 C 5 C lt 90 RH Operating environment 32 to 122 F 0 to 50 C lt 75 RH Storage environment 4 to 140 F 20 to 60 C lt 80 RH with battery removed Pump down indication When pumping down from atmospheric pressure to 2000 microns output of head goes from over 3VDC to 2VDC Overload 500psi 3400kPa Battery 9V Battery life 35 to 40 hours typical alkaline Red LED indicates battery is below operating level Auto off To extend battery life the AVG2 auto matically turns off after 5 minutes when reading above 70 000 microns The auto off switch is located beneath the rubber covering Use it to disable auto off function gt AUTO OFF Description The AVG2 vacuum gauge accessory head is a thermistor based digital multimeter accessory that enables most digital multimeters to digitally meas ure very low pressures associated with evacuating moisture from air conditioning and refrigeration sys tems It measures pressures between 50 and 2000 microns of mercury By selecting the prope
3. o not use an object such as a cotton swab to clean the sensor you may cause damage to the sensor Warranty The product is warranted to the original purchas er against defects in material or workmanship for a period of one 1 year from the date of purchase During the warranty period Fieldpiece Instruments will at its option replace or repair the defective unit This warranty does not apply to defects resulting from abuse neglect accident unauthorized repair alteration or unreasonable use of the instrument Any implied warranty arising out of the sale of Fieldpiece s products including but not limited to implied warranties of merchantability and fitness for purpose are limited to the above Fieldpiece shall not be liable for incidental or consequential dam ages WARNING When connecting hoses to the AVG2 vacu um gauge head HAND TIGHTEN ONLY DO NOT USE WRENCHES OF ANY KIND Use only hoses with knurled fittings How to use 1 Connect AVG2 vacuum gauge head to VOLTS OHMS and COM jacks on meter and select mVDC Slide onto Stick meter EHDL1 Electronic Handle or DL3 Data Logger You can also connect to meters with a mVDC scale and industry standard jacks by using ADLS2 test leads or AHDL1 Adapter Handle 2 Hand tighten your service hose from the refrig eration AC system service port to the AVG2 3 Your meter will readout pressure in microns of mercury Disable auto off for long evacuation
4. r range on the DMM you can verify that everything is properly connected and the pressure is going down from atmospheric pres sure to 2000 microns The sensor has been designed to withstand pres sures up to 500 psi 3400kPa so that no damage to the AVG2 will occur if it is exposed to full system pressures Applications Measure the vacuum on a refrigeration system when evacuating refrigerant The digital readout shows even small drops in pressure While target vacuum pressures vary the technician typically wants a vacuum between 300 and 400 microns for small systems and 700 for large systems Precautions and troubleshooting Before working on the system make sure there are no leaks A leak can make it impossible to pull the desired vacuum If there are no leaks the vacuum gauge is prop erly connected and working and the pump is work ing properly it may just be a matter of time before the vacuum reaches the desired level Moisture or gas pockets can cause the vacuum level to remain high until they are completely drawn out With the DMM in the VDC position you can see even small changes in pressure as the system pumps down If the vacuum gauge doesn t seem to work prop erly and you are sure you don t have leaks check for contamination of the sensor To check the vacuum gauge and the pump con nect it directly to a refrigerant pump using a very short hose If the pump is in good shape you should be able draw a vacuum down
5. s or for data logging with the DL3 4 To view the pressure dropping from atmospheric pressure to 2000 microns set DMM to VDC range Once reading is below 2 0 change range to mVDC to display pressure in microns Service Return any defective AVG2 to Fieldpiece for war ranty service along with proof of purchase Contact Fieldpiece for out of warranty repair charges Fieldpiece Designed in USA MADE IN TAIWAN v09
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