DURATECH FINISH ANALYZER

Transcription

1 DURATECH FINISH ANALYZER MIDAC M2000 FTIR UPGRADE MANUAL This manual contains additional information concerning the extraction unit settings, not found in the extraction unit hardware manual. Please read this manual. Duratech, Inc. 440 N. Commerce Ave. Waynesboro, VA Web: PHONE (540) FAX (540)

2 DURATECH FTIR UPGRADE MANUAL TABLE OF CONTENTS REVISION GNE WARRANTY 1.0 INTRODUCTION 2.0 MIDAC M2000 FTIR SPECTROMETER 3.0 GENERAL SYSTEM INFORMATION 4.0 FTIR SETUP AND CONNECTIONS 5.0 ALIGNMENT 6.0 DURATECH FTIR SOFTWARE 7.0 DURATECH JFOY v2.0 SOFTWARE 8.0 SYSTEM STARTUP 9.0 SCANNING YOUR FINISH OIL 10.0 SELECTING WAVELENGTHS 11.0 SYSTEM SETTINGS, PROCEDURES, AND HINTS 12.0 TROUBLESHOOTING AND MAINTENANCE

3 LIMITED WARRANTY - DURATECH FTIR UPGRADE PACKAGE DURATECH, INC. warrants all products of its manufacture to be free from defects in material and workmanship. This warranty is effective for one year from the date of delivery to the original Purchaser. DURATECH, INC. warrants all other products not of its manufacture but sold as part of this DURATECH, INC. system to be free from defects in material and workmanship. This warranty is effective for ninety days from the date of delivery to the original Purchaser. Upon prompt notification by the Purchaser, DURATECH, INC. will, at its option, repair or replace equipment that proves to be defective during the warranty period, provided the equipment is returned to DURATECH, INC. at the expense of the Purchaser. Parts, labor and return shipment to the Purchaser shall be at the expense of DURATECH, INC. Parts used and labor performed during on-site warranty service requested by the Purchaser shall be at the expense of DURATECH, INC. Travel costs shall be at the expense of the Purchaser. This warranty shall not apply to defects originating from: 1. Improper maintenance or operation by the Purchaser. 2. Purchaser-supplied accessories or consumables. 3. Modification or misuse by the Purchaser. 4. Operation outside the environmental and electrical specifications for the product. 5. Improper or inadequate site preparation. 6. Purchaser induced contamination or leaks. DURATECH, INC. reserves the right to make changes in design or construction at any time without incurring any obligation to make any changes whatsoever on units previously purchased. DURA- TECH, INC. assumes no obligation of any kind with respect to design or construction of products not of DURATECH, INC. manufacture. This warranty is expressly made by DURATECH, INC. and accepted by Purchaser in lieu of all other warranties, including warranties of merchantability and fitness for a particular purpose, whether written, oral, expressed, implied, or statutory. DURATECH, INC. shall not be liable for normal wear and tear, nor for any contingent, incidental or consequential damage or expense due to partial or complete inoperability of its products for any reason whatsoever. 440 North Commerce Avenue Waynesboro, Virginia Phone (540) FAX (540) duratech@cfw.com

4 1.0 INTRODUCTION Thank you for purchasing the upgrade package to replace your 980 with the latest in infrared spectrometers, the FTIR. The following sections will describe the installation and setup of the FTIR and the associated hardware. 2.0 MIDAC M2000 FTIR SPECTROMETER The Midac M2000 Series FTIR was chosen for this upgrade due to its ruggedness and high quality. Before proceeding, please read the FTIR SPECTROMETER OPERATOR MANUAL. You may disregard the Software section, as the Grams/386 and Spectra software packages are not included. The Installation section of the manual provides installation instructions and requirements. Connection to the DFA and cell installation are covered in the FTIR SETUP AND CONNECTIONS section of this manual. 3.0 GENERAL SYSTEM INFORMATION The FTIR uses a DMA (direct memory address) board that is installed in the P.C. It does not use an RS-232 interface, like the 980 that it is replacing. Duratech decided the easiest and fastest way to interface the data from the DMA board to the JFOY software was to write an interpreter program. JFOY v2.0 is written for DOS. All the software drivers and programs for the Midac FTIR were written for Windows. For this reason, the interpreter program was also written for Windows 95/98. The interpreter s function is to communicate with the FTIR through the Windows interface, and to provide the data to the JFOY software (in DOS). We communicate between the Windows program and the DOS program via the hard drive. Each program watches for a file on the hard drive, written by the other program. We call this bouncing the data off the hard drive. Basically, what the interpreter program does is this (see Figure 1 below): When a measurement needs to be taken, the JFOY software creates a specific file on the hard drive. The interpreter watches for this file to appear on the hard drive. When the file is seen, the FTIR is commanded to scan. When the scan is complete, the data is processed. The 4 wavelengths are converted to absorbances and placed in a second file on the hard drive, in the same order as the 980 would have transmitted them over the RS-232 cable. The JFOY watches for this file, retrieves the four absorbance values, and processes them as usual. Figure 1 - Bouncing the data off the hard drive to interface a Windows program to a DOS program. FTIR SOFTWARE (WINDOWS 95/98) JFOY SOFTWARE (DOS) HARD DRIVE

5 4.0 FTIR SETUP AND CONNECTIONS If you purchased a new DFA with the FTIR and are not upgrading, some steps do not apply. Please refer to each step to see it applies to you. Please do the following to set up your new FTIR: Remove the 980 (only if upgrading 980 to FTIR) Remove the flow cell from the 980 (if you purchased an FTIR cell, remove the tubing from your old cell and set the old cell aside). Turn off the 980, and unplug the power cord. Disconnect the RS-232 cable. Remove the 980 from the bench. Set Up The New P.C. Turn off old P.C., disconnect all the cables. Install new P.C., and connect all the cables. Set Up The FTIR Place the FTIR next to the DFA. Locate the tubing pass-thru plate on the rear of the FTIR. Pull on the clamping pin to release the top half of the plate. Feed the cell tubing through this opening, Insert the flow cell into the cell holder, and lock in place with the thumbscrews. Attach the cell tubing to the cell, routing the tubing so that it does not interfere with the IR energy path. This path is the circular area between the two round windows on opposite sides of the sample chamber. There is a cable tie above the left-hand window to secure the tubing, to insure that the tubing will stay out of the way. When done properly, only the cell stand and cell will be in the IR energy path. Replace the tubing plate on the rear of the FTIR, and push in the locking pin to secure the plate. Connect the FTIR cable to the rear of the FTIR and the P.C. Plug in the power supply and connect to FTIR. Turn on the FTIR and allow to warm up for minutes. Verifying FTIR Operation We have found that sometimes during shipment, the FTIR gets knocked out of alignment. This can cause a repeating knocking sound when the FTIR is powered up. A single knock when powering up is normal. If the FTIR is making unusual knocking noises, then it may need alignment. There are two types of alignment procedures outlined in this manual: Standard and Gross. Standard Alignment is used when the signal strength of the FTIR is low. Gross Alignment is performed when there is no signal at all and the FTIR won t respond (or there is the constant knocking noise). To verify FTIR operation and alignment, go to MODE and then ALIGNMENT in the Duratech FTIR software. The standard (or fine) alignment steps are covered in the Midac manual on pages 6-14 through 6-17 in the Maintenance Section and also under ALIGNMENT in this manual. For all steps in the alignment procedure, the Duratech software is used instead of the software referred to in the Midac Manual.

6 We recommend that you read the Midac manual, Chapter 5 Theory of Operation before you continue here. Examine Figure 2, showing the basic outline of the IR energy and the mirrors: M1 FIXED MIRROR SAMPLE MOVING MIRROR TO DETECTOR BEAM SPLITTER M2 Figure 2: Typical Michelson Interferometer SOURCE The two mirrors, M1 & M2, must be exactly perpendicular, both vertically and horizontally. The two Allen screws at the front of the FTIR that are used to adjust the alignment move the FIXED MIRROR to get it perpendicular to the moving mirror. The moving mirror moves back and forth slowly. If the alignment is off, the moving mirror can bump the stops at both ends causing the knocking noise. Or, it might not be not moving at all. To check the alignment, go to MODE and then ALIGNMENT in the Duratech FTIR software. Click on START ALIGNMENT. If the moving mirror is scanning, you should should see the screen below:

7 The previous screen shows an FTIR with good alignment. The shape in the center is called a centerburst. The MIN VALUE and the MAX VALUE are what we are checking. Notice that the MIN peak can be larger than the MAX peak (this is normal, the values may be the same or reversed). The maximum value of each peak is 32,768. Examine the LARGER peak value. Midac recommends that the signal be about 70% - 90% of full scale, or between 23,000 and 29,500. A value of greater than 90% may saturate the detector and cause errors in results. If your Midac is poorly aligned, you may see something like this: As you can see, the centerburst is very small. The (larger) peak value is far too low for good operation. An FTIR with this value needs a standard (fine) alignment. NOTE: IF YOU CANNOT DISPLAY THE CENTERBURST, THE FTIR MAY BE TOO FAR OUT OF ALIGNMENT TO PRODUCE ANY SIGNAL AT ALL. THE FTIR WILL NOT COMMUNICATE WITH THE COMPUTER IN THIS CASE. GO TO THE GROSS ALIGNMENT PROCEDURE AND CHECK OPERATION OF THE MOVING MIRROR.

8 5.0 ALIGNMENT The Midac manual shows you how to make the adjustments using the wrenches. We are showing the same basic information here. Use these as a guide. However, with practice you will develop a "feel" for the procedure that will enable you to quickly achieve good signal strength. The LARGER peak value should be higher than 23,000 for best performance, but no more than 29,500. This is the section that is in the Midac manual, starting on page We are re-wording it here because the software you will use is not covered in the manual. First, start the Duratech FTIR Software. It is located in the Duratech Folder, or on your desktop. Under MODE on the menu, select ALIGNMENT. Click on START ALIGNMENT. Standard (Fine) Alignment Procedure When making FINE adjustments, move the wrenches very slowly (only a few degrees). NOTE: The Midac manual does not mention this, but when moving ONE wrench, the other wrench also moves. So when moving ONE wrench, you should hold the other wrench tightly. A B MOVE BOTH CLOCKWISE C MOVE BOTH COUNTERCLOCKWISE D MOVE APART MOVE TOGETHER SLOWLY adjust the two Allen wrenches while you observe the reading displayed beneath the interferogram. Very fine adjustments can affect the signal greatly, so it is important to move the wrenches very gradually. After you adjust the wrenches, pause for a moment to give the reading a chance to stabilize before making your next adjustment. This procedure may take a long time, until you get the "feel" of the adjustments. Very little movements may make a large difference! A. Begin by slowly rotating both wrenches together in a clockwise direction. If this increases the signal, continue with gradual adjustments in the same direction until you reach, then pass, a maximum value. When the value starts to decrease, back up to the maximum and proceed to 'C' below. B. If the first clockwise adjustment caused the signal to fall, slowly rotate both wrenches counterclockwise until you reach, and pass, a maximum value. Once you pass through the maximum, back up until you reach it again and proceed to 'C' below.

9 C. Turn the two wrenches in opposite directions (away from one another) in very small increments. Repeat steps 'A' and 'B' and observe the signal value. If the value increases, move the wrenches a little farther apart and adjust clockwise / counterclockwise to achieve a maximum signal. D. If the first adjustment in step 'C' did not increase the signal strength, turn the two wrenches slightly toward each other. Repeat steps "A' and 'B' and check the signal value. If it increases, repeat until you find a new maximum. When your signal level falls in the satisfactory range, the mirror is aligned. Remove the Allen wrenches. Replace the adjustment port cover and put the flow cell back in.

10 Gross Alignment Procedure First, check the operation of the moving mirror: TURN OFF POWER TO THE FTIR. #1 Remove the left top cover. #2 You will see the laser on top of a metal box. Look under the rear of the laser (the left end) inside the box, and you will see a wire coil around a square bar. You should be able to slide the coil back and forth very easily. The coil is bronze colored. If you look inside the box the laser is sitting on, you can see two arms that rock back and forth as you move the coil. This coil is attached to the scanning mirror inside the box. When the FTIR is working properly, this coil should slowly move back and forth about 3-4mm on the square bar. WHEN YOU FIND THE COIL, GO TO THE STEP. #3 TURN ON POWER. Is the coil slowly moving back and forth? If it is NOT, or if the coil is banging one or both ends, then the alignment is very bad. The FTIR may not communicate with the PC if the alignment is this bad. The Midac FTIR manual does not describe the next steps. This is something that Duratech found, that helps the process considerably. #4 On the side of the box, above the large hole, is a laser sensor. It is below the front of the laser. There are two small white wires coming from the sensor and going into the box. It s location is shown in the above diagram. #5 Gently remove the laser sensor. It is in a black plastic container. Set it on top of the box.

11 #6 Turn on the power. You will see one or two laser spots on the back wall of the FTIR, coming out of the laser sensor hole. One is fixed, and the other spot moves when you adjust the fixed mirror with the wrenches. HINT: Put a piece of dark paper against the wall to reduce the laser brightness and glare so it is easier to see the tiny spots. #7 Use the wrenches to adjust the fixed mirror as you did before, and watch the two spots. You want to get the moving spot directly on top of the fixed spot, so it looks like there is only one spot. This means that the two mirrors are very close to being properly aligned. #8 When you have the moving spot on top of the fixed spot, put the laser sensor back in it's hole. The coil should start moving. If you got the moving spot on top of the fixed spot, the coil should be moving slowly back and forth about 3-4mm. HINT: If you cannot clearly see two spots, move the wrenches until the two spots separate. This way it is easier to get them lined up. #9 Go to the STANDARD (FINE) ALIGNMENT PROCEDURE section and optimize the FTIR.

12 6.0 DURATECH FTIR SOFTWARE The figure below shows the screen of the FTIR software, after a reference scan of polystyrene. General: Wave Number - Shows the current wave number for the VERTICAL red line. Center Position - Shows the current center position of the graph. Use the arrows on either side to scroll the spectrum right and left. (This is not available when a full spectrum has been selected. See Options settings below.) Amplitude - Shows the current amplitude for the HORIZONTAL red line. If displaying an Absorbance plot, shows Absorbance Units. If displaying a %Transmission plot, shows %Transmission. Graph Area - Shows the current scan. Can be either a Reference Scan or Sample Scan and be displayed in either Absorbance Units or %Transmission.

13 Menu Items Description: File Exit - Exits the program Collect Params Set Default - Returns all configuration settings to their default values. Gain - Sets gain to AUTO, 1, 2, 4, 8, 16, 32, 64, or 128. The default value is 1. Resolution - Sets the resolution. The resolution setting affects how much time it takes to complete the scan. The default value is 2. With a setting of 2, it takes about 10 seconds to complete a scan. Higher settings are unusable for the DFA. However, if you are performing some routine scans and need a higher resolution, you may temporarily change this value. IF YOU DON T RESET IT TO 2, THE DFA WILL STOP WORKING!! Scans - Sets the number of scans that will be averaged. The default number of scans is 4. The FTIR will average 4 scans then report the result. This setting gives more than adequate performance for the DFA. Higher settings are unusable for the DFA, as the increase in time will be too large. However, if you are performing some routine scans and need higher sensitivity, you may temporarily change this value. IF YOU DON T RESET IT TO 4, THE DFA WILL STOP WORKING!! Mode Alignment - Sets the FTIR to Alignment mode. This is used to align the mirrors on the FTIR. Analysis - Sets the FTIR to Analysis mode. This is used for normal operation and when running scans. Options Slave Y to X - Slaves Y slider movement. When scrolling the X slider, the Y slider will automatically follow the X. This is useful when locating peak values. Spectrum - Selects the minimum and maximum displayed wavenumbers or microns. Test Points - Selects wavenumbers (microns) for your analytical & reference testing (see SELECTING WAVELENGTHS section). Units - Sets the displayed units to either microns of wavenumbers. Zoom None - Sets the zoom setting to 1 X1.5 - Sets the zoom setting to 1.5 X3 - Sets the zoom setting to 3 X6 - Sets the zoom setting to 6 Help About - Gives latest program release version. Check the Duratech Web page for updates.

14 Button Description: Get Reference - Gets the background spectrum. Used only when PURE solvent is in the cell or when scanning a polystyrene card without a cell. Get Sample - Gets the sample spectrum. Used when a sample is in the cell or when scanning a polystyrene card without a cell. Absorbance - Shows the absorbance plot for both reference and sample spectra. %Transmission - Shows the %T plot for both reference and sample spectra. Clear Plot - Clears the generated plot from the screen.

15 7.0 DURATECH JFOY v2.0 SOFTWARE The software that came installed on the P.C. and with the FTIR must be used. It has been modified to work with the FTIR. If you have any problems with communication to the DFA ( like DFA ID DOES NOT MATCH DISK ID ) you will have to run the factory setup. To do this, go to F-CONFIG. Be sure your caps lock key is OFF. Type in irvin then press enter. (Just start typing, you won t see anything on the screen.) The factory setup menu should appear: Enter your DFA serial number, and select Y when asked if you want to program the serial number into the DFA. Enter the rest of the values as shown above. When you reach the concentration analyzer screen, select Midac FTIR as shown below: When done, operate the JFOY software as before. The FTIR operations are transparent.

16 8.0 SYSTEM STARTUP The power to the DFA, P.C. and FTIR should be left on at all times. If you are turning on the P.C. or had to reset it for any reason, start the software as follows: #1 - Start the FTIR program. You can minimize it if you wish, it will simply run in the background. #2 - Start the JFOY program. The software will be located on the Desktop and also in a Duratech folder under the Start Menu. To run the software from the Desktop, double click on the FTIR icon to start the FTIR software and then double click on the FOY icon to start the JFOY software. To run the software from the Start Menu, click on the Start menu, move the mouse arrow up to Programs, then onto Duratech, and then click on the FTIR icon. Repeat to start the JFOY software.

17 9.0 SCANNING YOUR FINISH OIL The FTIR software has default values that should work well to measure DMAC and silicon oil. However, you are free to select your own wavelengths. IF SELECTING YOUR OWN WAVELENGTHS, DO NOT USE THE NUMBERS FROM YOUR 980 The 980 s are not perfectly repeatable unit to unit like FTIR s. Follow the instructions below to find appropriate wavelengths: Have both JFOY and FTIR running. (Use ALT + TAB to switch between the two programs.) In F-Manual, fill a cup and rotate it under the drain tube. Press F4 - Drain Cup to drain the cup, placing the pure solvent into the flow cell. Press ALT + TAB to switch to the FTIR software. Click GET REFERENCE and wait for the spectrum to appear. Press ALT + TAB to switch to the JFOY software. Place a cup with oil or DMAC or both in the turntable, fill it, and rotate it under the drain tube. Drain the cup, placing the sample into the flow cell. Press ALT + TAB to switch to the FTIR software. Click GET SAMPLE and wait for the spectrum to appear. Click %TRANSMISSION to view the spectrum. HINT: To convert wave numbers to microns: MICRONS = 10,000 / WAVENUMBER You should find the DMAC peak near 6.0µm (1667 wavenumbers), and the silicon peak near 8µm (1250 wavenumbers). Zoom in using the x3 scale to place the red line at the peak for best accuracy. Select a reference where the %T is high, and in a valley. Look near 5µm (2000 wavenumbers). You can use a single reference for both DMAC and oil, or select a reference next to the base of each of the analytical peaks. IMPORTANT: The JFOY software only recognizes the Other Component when calibrated as Finish #0. THIS IS THE ONLY FINISH LOCATION THAT WILL WORK WITH THE SECOND COMPONENT. When calibrating the second component, enter Finish #0 when prompted. If a calibration curve exists for Finish #0, DMAC will automatically be calculated and appear on the printout. If you are upgrading to FTIR, you already know this. Calibrate the DMAC as usual. If for any reason you are not allowed to enter Finish #0 when prompted, the CONFIG.DAT file needs to be modified. Use the HEADERS.EXE program (if you have it), or simply use DOS s EDIT to edit the file. Locate the line: Denier: standard and change to: Denier: lycra

18 10.0 SELECTING WAVELENGTHS From OPTIONS select TEST POINTS. The screen below will appear: You can enter your chosen wave numbers in this window. The box Finish Component is for the primary finish oil of interest, and the box Other Component is for a secondary material in the solution that you wish to monitor. NOTE: This window contains a set of default values that represent Silicon oil as Finish Component and a solvent called DMAC as the Other Component. FLOW CELL DISCUSSION: The DFA8980 / FTIR is a system optimized for measuring two components that are dissolved in perclene. Perclene itself has a background spectra at shorter wavelengths in the infrared region. It is important to be sure that you minimize the effect of perclene s background by using a short pathlength when testing above 6-7 microns. Silicon oil has a peak at approximately 8µm. Perclene has a background here also. To see the background for perclene, do the following: Remove the flow cell. Click GET REFERENCE (using air as reference). Insert flow cell and flush with clean solvent. Click GET SAMPLE to scan the perclene. Click %TRANSMISSION to view perclene's waveform. Examine the area at 8µm to see how much background (or blocking ) perclene has at 8µm. Typically, we have used a 1mm flow cell for all systems measuring silicon oil and DMAC to minimize the perclene background. These cells were either a Duratech Variable Pathlength cell, using standard 13mm x 2mm CaF2 windows, or a Foxboro cell with 22mm CaF2 windows. Both the Duratech and Foxboro cells have a 3/8 aperture. However, since we are using an FTIR, we are shipping an off the shelf FTIR cell with new DFA systems. FTIR cells have a 1/2 aperture to allow more energy through them. These cells are available to upgrade FTIR users also. However, the 3/8 aperture cell has tested satisfactorily for use with the FTIR. We are shipping the FTIR cell because it is an off the shelf item, and uses standard sized windows.

19 11.0 SYSTEM SETTINGS, PROCEDURES, AND HINTS SYSTEM SETTINGS There is only one system setting on the DFA that must be changed if upgrading to the FTIR. This system setting is the SAMPLE PUMP UP TIME, located in F-CONFIG, (under F3 - Extraction Unit). When a cup is ready to be tested, the sample pump goes through the following cycle: 1 - goes down, drawing in the sample. 2 - reaches bottom and starts the SETTLE TIME delay to let the sample settle in the flow cell. 3 - goes up and discharges the sample to waste. The DFA orders a reading to be taken when the sample pump goes up, after the sample has settled. The usual time for the SAMPLE PUMP UP is 5 seconds. The Duratech DTIR s reading is ready immediately; The Miran 980 and Duratech 980's response is about 4 seconds. However, the FTIR takes about 10 seconds for a response. If the SAMPLE PUMP UP time is only 5 seconds, this means that the sample pump can start the flush (pure solvent) before the reading is finished. THEREFORE, PLEASE BE SURE THAT THE SAMPLE PUMP UP TIME IS SET TO A MINIMUM OF 10 SECONDS. WE RECOMMEND A SETTING OF 15 SECONDS, AS LONG AS YOUR CYCLE TIME ALLOWS IT. The usual cycle time for the DFA8980 is 2 minutes, which easily allows a 15 second setting. PROCEDURES Gain Setting (in Duratech FTIR Software): After the alignment has been checked and adjusted if necessary, insert the flow cell and perform the following to insure best operation of the FTIR: Flush the cell with pure solvent. Go to ALIGNMENT and start alignment. You will see a reduced signal from having the cell and solvent in the path. Stop the alignment and increase the gain setting (usually a setting a 2 is fine). Go back to the alignment screen and verify the following: PEAK VALUE (MAX & MIN) : No larger than 29,500 each. Check BOTH values! One peak may be larger than the other (this is normal).

20 12.0 TROUBLESHOOTING AND MAINTENANCE Verify System Operation By Scanning A Polystyrene Card A good way to verify the operation of the FTIR is to scan a polystyrene card. This is a standard method of verifying the FTIR, as the card has many identifiable peaks. Included with your FTIR is a card and a scan of what the waveform should look like. To perform a scan, remove the flow cell and set it aside, out of the path of the 3 windows in the cell compartment, then: Close cover and wait about 5 seconds for the FTIR to stabilize. Click GET REFERENCE. Wait for the background spectrum to appear. Open the cover and insert the card. Close the cover. Wait about 5 seconds, then proceed. Click GET SAMPLE. Wait for the background spectrum to appear. Click %TRANSMISSION to view the waveform of the polystyrene card. Now is a good time to familiarize yourself with the ZOOM settings, the CENTER POSITION arrows, and the scroll bars as discussed in the DURATECH FTIR SOFTWARE section of this manual. Slide the horizontal scroll bar until the red line is at any peak of the waveform (peaks point DOWN when viewing %Transmission). You do not need to use the vertical scroll bar at this time. The wavenumber is shown in a box at the top of the screen. You can verify this measurement by referencing the diagram below. An example is shown checking peak #3:

21 Peak Values PEAK WAVE NUMBER PEAK WAVE NUMBER Your measured values generally should be within ±6 wavenumbers of the values above. In some cases you may not be able to obtain the exact number above (i.e. the display jumps from 1945 to 1943). Use the ZOOM to measure the peaks more accurately. You may also type a wave number in the text window to get the desired value. FTIR Maintenance The Midac FTIR requires very little maintenance. Once set up, it should run for a very long time without incident. Please read the Maintenance section of the Midac FTIR manual for more information. However, during shipping, the FTIR may have lost alignment of it s fixed mirror. This requires an alignment procedure to be performed (discussed previously in this manual). FTIR Flow Cell Maintenance The optional FTIR flow cell is off-the-shelf from Wilmad except for the spacer. It uses standard 19mm diameter x 2mm thick CaF2 windows. The spacer is 316 stainless steel. To clean the cell: Unscrew the bezel from the front of the cell and remove all components, noting the order that they came out. Clean windows with a solvent other than perclene that is also safe for the window material. Rinse the stainless steel spacer with the solvent. Re-insert components in reverse order, being sure to line up the thin sections of the spacer with the inlet and outlet holes on the cell body. If possible, place the spacer so that the thin sections block the smallest portions of the openings as possible. Screw on the clamping bezel being careful not to overtighten. Flush the cell 2-3 times and inspect for air leaks. NOTE: Some amount of tiny bubbles is normal in the 1/4 line, due to the perclene being pulled through the small holes in the cell at a fast rate. Replacement parts can be ordered from Duratech, or directly from the manufacturer.