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AMI Analyzer Manual

Analyzer Description

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Sample Handling:

Figure 7 Flow Schematic

The sample is brought into the sample/span selection valve which contains an integral flow control needle
valve.

The sample (or span gas) passes through the sensor compartment and exhausts through the flow meter.

The exhaust must be vented in such a fashion that the line will not freeze up, but on the other hand the
flammable gas leaving the exhaust line will not pose a hazard. If there is a possibility of losing flow, a back-
diffusion assembly should be used to safeguard the sensor against high oxygen levels from air saturating it.

NOTE: Never allow the vent to become restricted, thus back-pressuring the sensor. Doing so
will cause inaccurate readings and may damage the sensor

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Содержание Watchdog

Страница 1: ...AMI Oxygen Analyzer Manual Watchdog AMI Costa Mesa CA ...

Страница 2: ...chdog Oxygen Analyzer 5 Introduction 5 Features 5 Oxygen sensor 4 Sensor Warranty 4 Instrument Warranty 4 Installation and Operation 5 Receiving the analyzer 5 Installation 5 Points to consider first 5 Location 6 Safety Considerations 6 Flashing Display 6 ...

Страница 3: ...nents 21 Leaks 21 Exhaust 21 Calibrating the analyzer 21 Gas Connections 23 Power connections 24 Output connections 24 Sample Handling 25 Gas pressures 26 Sensor Installation 26 Hydrogen Sulfide 26 Communications 26 Advanced Features 26 Maintenance and troubleshooting 27 Maintenance 27 Periodic Calibration 27 Sensor Replacement 27 Shorting clip 27 Sensor replacement cautions 28 Sensor replacement ...

Страница 4: ...AMI Analyzer Manual 3 Basics of trace oxygen troubleshooting 30 Specifications and Disclaimer 34 Specifications 34 Disclaimer 35 ...

Страница 5: ...ce Oxygen measurement is difficult because the air contains high levels 209 000ppm of oxygen and it will get into the smallest leaks Oxygen molecules will enter through a leak no matter the pressure or the nature of the gas in the line This analyzer is an exceptionally sensitive leak detector including those provided by improper installation Make sure you read this manual carefully prior to instal...

Страница 6: ...See Note 1 Calibration history stores the last five calibrations with time date span factor and calibration gas See Note 1 Brown out history stores the last five brown outs and recoveries See Note 1 Power up history stores the last ten times the unit was powered up See Note 1 Advanced analog output calibration Power requirements 10 28VDC Low minimum detection limit Excellent repeatability Fast ups...

Страница 7: ...r come down times typically under twenty minutes to 10ppm from a 1 minute air exposure Sensor Warranty The sensor is warranted to operate for a period determined by its class If the sensor ceases to operate correctly before this time has elapsed contact AMI for a return authorization for evaluation If there is any evidence of defective material or workmanship the sensor will be replaced free of ch...

Страница 8: ...e temperature range going to be where the analyzer will be installed If the temperature is going to go below freezing you need to place it in a temperature controlled meter building If this is not possible you should really be using a heated 2010BR Also make sure it won t get too hot in the summer you may need to ventilate or even air condition a building Use a solar panel as a sunshield if one is...

Страница 9: ...ected do not to mount it close to sources of electrical interference such as large transformers motor start contactors relays etc Also avoid subjecting it to significant vibration don t mount it on the side of a compressor Give yourself enough clearance on the right side that you will not have a hard time connecting the gas lines Safety Considerations The unit is designed for installation in eithe...

Страница 10: ...h quality ground with a minimum 16AWG wire 3 Confirm sample pressure is less than the analyzer specification 150psig 4 Deal with any potential condensation or liquid contamination issues 5 Connect the sample line to the sample inlet port with ss tubing 6 Turn the Sample Span Off valve to the Off position 7 Pressurize the sample line to line pressure between 1psig and 150psig 8 Leak check every fit...

Страница 11: ... 22 Remove the USB connection cable 23 Replace the access panel on the side of the analyzer 24 Purge with sample gas for half an hour or until the oxygen reading has fallen to low ppm levels 25 If desired span with known calibration gas Laptop set up procedure 1 Make sure the laptop has the FTDI driver installed a Windows 7 will probably find the driver by itself but XP probably won t b Run the pr...

Страница 12: ...al gas world 10 Make sure the security settings are the way you want them 11 Make sure the display shows the correct output type 1 5V or 4 20mA 12 Go through the analog output calibration procedure if desired 13 If you are installing the sensor click on the New Sensor button and write in the serial number 14 Check the analyzer date and time is correct we set it up for Pacific Standard time which m...

Страница 13: ...if possible at a convenient eye level not too close to the right wall The gas connections are made on the right side of the analyzer while the electrical connections are on the left side Leave enough space on the right side of the analyzer for the gas connections The analyzer can be mounted on a wall or on a two inch pipe If the analyzer is mounted outside make sure it has some kind of sun shade I...

Страница 14: ...it You can roughly calculate it by assuming that the volume of tubing the length multiplied by its internal area has to be completely replaced by the gas flowing before you get a representative reading If the sample pressure is high the volume is effectively increased because more gas is packed into the tubing AMI can provide a version of the Liquid Rejection Probe with a built in regulator that c...

Страница 15: ...a liquid soap solution such as Snoop or similar Don t spray it on You are looking for little bubbles that appear after a while indicating a leak Even the tiniest leak will allow oxygen to enter the gas stream no matter what the pressure inside the line is Check absolutely every possible source including welds valve packing and fittings both around the tube and the nut and anything else that might ...

Страница 16: ...sensor which will increase the oxygen reading 11 Leave the Sample Span Off valve on the analyzer pointing to SAMPLE and allow the sample gas to purge the unit while you wire it up You want to get rid of all the oxygen trapped in the tubing fittings and dead areas in the cell block Also at the oxygen levels we are normally measuring we essentially have to flood the whole sample system with enough g...

Страница 17: ... per the markings Positive to ve return to the ground symbol This terminal should also be used if required for any shield connections for the output or RS485 connections The output connections are made on positions 3 and 4 and the RS485 connections on 5 and 6 The analog output which may be either 1 5V or 4 20mA is connected to the and symbols 3 and 4 This signal is isolated from ground If the devi...

Страница 18: ...ull out the tag Do it in this order so that the sensor is always operating eating up oxygen that gets in through its membrane The length of time you take over this is critical in determining how long the sensor takes to get down to a low range 16 Optional in the User Interface version III press the NEW SENSOR button and record the sensor serial number You might just want to write it down Note that...

Страница 19: ... This effectively removes trapped oxygen from the air in the primary side of the regulator If you just try to purge it by flowing gas through it it will take a very long time to get rid of all the air and you may contaminate the gas in the bottle Bleeding the regulator can save days of time c Bleed low pressure side of the regulator 7 times Removes the air from the secondary side Bleeding the regu...

Страница 20: ...e leak is The longer it takes for the flow change to affect the leak the further from the analyzer is the leak source Fix it by using Snoop and try again j If so adjust the analyzer span until it reads the span gas value Press the SPAN button The SPAN flag should appear on the LCD Press the UP or DOWN arrow buttons until the reading is correct After a few seconds the SPAN flag will go out and the ...

Страница 21: ... enclosure The sample system components are all integrated into a Cell Block located behind the front panel on the right and the electronics are contained on a single circuit board also located behind the front panel on the left All the electrical connections are available under a panel on the left side of the instrument The actual oxygen measurement is performed by an oxygen sensor located behind...

Страница 22: ...AMI Analyzer Manual Analyzer Description 19 Figure 5 Outline Drawing ...

Страница 23: ...eing pure oxygen at 3 psia pressure In a pure gas stream or in natural gas there is zero oxygen ideally i e it is at zero pressure This means that if there is a leak in the piping there exists a pressure difference of 3psia forcing oxygen into the leak The oxygen doesn t care about or see the other gas in the pipe it thinks of the pipe as being a vacuum People normally don t intuitively understand...

Страница 24: ...nd breaking them too often Leaks If you suspect a leak due to high oxygen readings change the flow rate and see how long it takes for the oxygen reading to change A higher flow rate will dilute the effects of a leak so that the reading will drop as you increase the flow this is a very good way of making sure that you do not in fact have a leak by the way Turn the flow up from 1 SCFH to 2 SCFH usin...

Страница 25: ...everal minutes with a small flow of gas prior to doing this and leave the gas flowing while you make the connection to the analyzer This prevents a slug of air from giving you excessively high readings when you start spanning the analyzer Make sure the analyzer is seeing a low oxygen level gas you want the analyzer to go UP to the span gas not down to it particularly not from air Otherwise it will...

Страница 26: ...or with the UP or DOWN buttons and see what the analyzer says the gas contains If the gas value isn t what you think it should be it is the gas that is wrong not the analyzer because that air calibration is in fact very valid You will have to trouble shoot whatever has happened with your gas Gas Connections Do not install the sensor until the gas lines have been connected and the electrical connec...

Страница 27: ...8V the unit will shut down until the excess voltage goes away unless the voltage exceeds 240V in which case the unit will be damaged At some point below 7V the unit will shut down with no damage The unit is supplied with a six position connector The connections are as shown in the drawing below Figure 6 Electrical connections viewed from the analyzer side The ground stud on the bottom of the box M...

Страница 28: ...he flow meter The exhaust must be vented in such a fashion that the line will not freeze up but on the other hand the flammable gas leaving the exhaust line will not pose a hazard If there is a possibility of losing flow a back diffusion assembly should be used to safeguard the sensor against high oxygen levels from air saturating it NOTE Never allow the vent to become restricted thus back pressur...

Страница 29: ...LATOR MUST BE THOROUGHLY BLED See Bleeding a Regulator below for details Hydrogen Sulfide The standard AMI T 2 sensor can withstand up to 10ppm of hydrogen sulfide for its expected life while the optional T 4 sensor can withstand up to 500ppm of hydrogen sulfide for its expected life Communications The Watchdog supports both a USB link to a local PC and RS485 over a network Only one of these can b...

Страница 30: ...s the sensor ages during each calibration this factor will increase It will start around 450 and by the time it reaches 1000 the sensor is dead By 850 the sensor is getting pretty dubious and it would be a good idea to replace it at that point Sensor Replacement This should be done periodically rather than as a response to a dead sensor See the chart below for recommended sensor replacement Sensor...

Страница 31: ...e MSDS to learn about potential hazards and corrective actions in case of any accident Figure 8 Inserting sensor in cell block Sensor replacement procedure 1 Turn off the sample gas flow using the flow selection valve on the front panel 2 Unscrew the cell cap 3 Remove the old sensor 4 Open the bag containing the new sensor 5 Push the new sensor into the block using its handle as shown above 6 Hold...

Страница 32: ...he regulator and close it again 4 Use Snoop or equivalent to completely leak check the regulator gauges fittings and bottle valve 5 Loosen the nut connecting the regulator to the bottle and allow the high pressure gauge to bleed off to zero and then immediately tighten it again 6 Open the regulator to its full pressure 7 Repeat steps 3 and 5 seven to ten times 8 Set the regulator to its correct ou...

Страница 33: ... these things will cause the sensor to read too low Reading too high is normally caused by too much oxygen either in real time due to a leak or else because the sensor has been saturated with air You may be able to detect this latter by looking at the data log If you suspect a leak due to excessive oxygen readings you can often get an idea of where it is by changing the sample flow rate If the oxy...

Страница 34: ...eached the end of its life or there is some other calibration error Using the user interface you can read the previous span factors as well This number always goes up as the sensor ages it is changed every time you span the analyzer it doesn t change by itself So if it goes down something is wrong You have more oxygen in the span gas than you thought or there is something wrong with the analyzer b...

Страница 35: ...analyzer reads zero if not there is moisture or corrosion between the sensor contacts in the cell block clean the contacts and the area around them with isopropyl alcohol dry with dry compressed air or nitrogen then replace the cap on the cell block again Pressurize the system to no more than 10 psig and leak check all the fittings and tubing including the sensor block penetrations such as the sen...

Страница 36: ...put should be around 150 to 750 micro Amps in air This will take a few minutes to stabilize as the sensor consumes oxygen dissolved in its electrolyte Replace the sensor if it does not read this amount See sensor replacement instructions under Maintenance Incorrect readings 1 Verify that there are no leaks in the system 2 Verify that the span gas bottle is correctly marked by comparing its reading...

Страница 37: ...m detection 50ppb of oxygen Repeatability 1 of range or 0 2ppm of oxygen whichever is greater Operating temperature range 25 to 115 F Diurnal temperature specification 3 of scale over temperature range 90 upscale response times 10ppm 25 10 seconds 0 10ppm 25 seconds Typical downscale response 1 minute exposure to air down to 10ppm 15 minutes Area Classification Designed to meet requirements for Cl...

Страница 38: ...s or associated components AMI s obligation is expressly limited to the analyzer itself The AMI analyzer is not designed as a primary safety device that is to say it is not to be used as the primary means of assuring personnel safety In particular it is not designed to act as a medical instrument monitoring breathing air for correct oxygen concentration and should not be used as such when it is th...

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