Operation Of The Perkin-Elmer 1300 Series Infrared Spectrophotometer In Scheduled Oil Sampling{0645} Caterpillar

Introduction

Any one of several infared spectrophotometers are acceptable for use in the Scheduled Oil Sampling program. This instruction shows the correct procedure for operation of the Perkin-Elmer 1300 Series Infrared Spectrophotometer. Installation of this instrument may vary due to physical differences in the layout of each Laboratory. In all cases, however, follow the installation instructions of the manufacturer.

NOTE: This instruction is intended to be used along with Perkin-Elmer instruction manuals.

Operation Principle

(1) Infrared radiation is produced by an electrical heat source. The radiation from the source is divided into two beams. It is then focused into the sample area by mirrors (M1) and M2).

(2) The reference beam passes through the reference cell (if present) and the sample beam passes through the sample cell.

(3) The reference beam now passes through the attenuator and is reflected by mirror (M3) to the rotating sector mirror (M5). Next, the reference beam is alternately reflected to mirror (M6) or is allowed to pass out of the optical system. The reference beam is now an intermittent beam.

(4) The sample beam is reflected by mirror (M4) to the rotating sector mirror (M5). This allows the sample beam to reflect to mirror (M6) or be blocked out of the optical system. The sample beam has now become an intermittent beam.

(5) The alternating segments of the reference and sample beams are focused by mirror (M6) to the flat mirror (M7) and reflected to mirror (M8) at the entrance slit (S1).

(6) The combined beam now continues to mirror (M9), then to the monochronometer which disperses the infrared energy into its component frequency.

(7) The beam is now reflected back to mirror (M9) and on to mirror (M10) at the exit slit (S2). The beam then continues to mirror (M11) and is focused on the detector. Filters are automatically inserted in order between mirror (M1) and the detector during scanning to eliminate unwanted radiation. The grating is mechanically linked to the chart drive.

(8) The thermopile detector measures the radiant energy received by measuring its heating effect. The intensities of the two beams at any frequency are compared.

(9) When the intensity of one beam changes, the detector develops an electrical signal which causes a motor to position a linear optical attenuator in the reference beam so the intensities of the beams become equal.

(10) The amount the attenuator must move to equalize the intensities of the two beams is directly proportional to the sample beam intensity.

(11) The recorder pen drive is mechanically coupled to the attenuator.

(12) The movement of the attenuator and recording pen is a direct measure of the absorption of the sample.

(13) Since the chart is mechanically linked to the grating, which determines the frequency of the radiator detected, the absorption at each frequency is recorded.

Optical diagram for Perkin Elmer Infrared Spectrophotometer

Chart Paper

Since measurements can be read directly, the 1/2 scale absorbance paper (Perkin-Elmer Part # 199-104) is used. This paper has a logrithmic ordinate scale and markings of .1, .2, .3, .4, .5, and 1.0. Use this type of paper only.

The numbers along the top and bottom are both wavelengths in absorbance. At the top is the length of one wave in micrometers or millionths of a meter. At the bottom is the number of waves per centimeter.

Cells

(A) Construction - Two types of cells are available. They are sealed and demountable sealed. The sealed cells are permanently assembled with the desired arrangement of spacers and windows. The demountable sealed cells can be disassembled and assembled with the desired arrangement of spacers and windows. The sealed cells have film thickness consistency, therefore they are more uniform. The optimum spacer thickness has been found to be 0.1 mm. Demountable cells are recommended because the windows can become discolored due to heavy sooted oils.

(B) Cleaning and Filling - A vacuum arrangement is suggested for cleaning cells. It can include a pressure-vacuum pump (Wilkens Anderson Part # 73020-00), a tank as a reservoir (approximately 1/2-1 gallon), a connector for attaching the vacuum line to the cell, and the necessary fittings and tubings.

The cell is cleaned simply by flushing solvent (hexane) through the cell while applying a vacuum. When air is observed flowing through the cell, spray solvent in the open FILL port using a wash bottle. The cell is clean when all the streaks have disappeared. The hexane is evaporated in a few seconds by the air drawn through the cell by the vacuum pump.

Before filling the cell, shake the oil sample thoroughly in a paint shaker. Allow the sample to stand for 15 minutes to let the air bubbles escape. If the sample has stood for more than 60 minutes, shake it again by hand for 5 seconds.

To fill the cell, set it on a table at an angle approximately 30° from horizontal. Stir the sample briefly with a stirring rod. Use the stirring rod to transfer 2-3 drops of the sample into the lower FILL port of the cell. Very gently, with slow and steady pressure, insert a plug in the lower FILL port. This pushes the oil into the cell. Check for air bubbles by holding the cell up to the light. If there are any, repeat the procedure.

(C) External Attenuator - On heavily soiled oil samples, the 100% control will not raise the baseline enough on the chart paper to generate a usable spectrum. On some samples from other compartments, the baseline cannot be lowered enough to keep the pen from running off the top of the chart paper. For these samples, an external attenuator is mounted on the cell to further block the light beam. To raise the baseline, the attenuator is mounted on the reference cell.

The attenuator recommended is the slotted comb type available from Perkin-Elmer. The attenuator is modified by replacing the mounting plate with a bracket available from Caterpillar. To obtain this, contact Service Development G.O.

How To Run A Sample

(1) Complete the heading on the chart paper.

(2) Insert cells and pen into the correct holders. Put the reference cell (new oil) in compartment (1). Put the sample cell (used oil) in compartment (2).

(3) Check and adjust the gain for 10% deflection at 2000 WN (Wave Number).

(4) Set the 100% control.

a) For diesel engines only, get the soot index by moving the table to 2000 WN and turning the 100% control for maximum T (Transmittance).

b) While still at 2000 WN, set to 80% T. If 80% T cannot be reached using the 100% control, use the external attenuator comb.

(5) Move the table to 4000 WN.

(6) When all the samples have been run, remove the pen from the holder (3) and cap it.

General Operation Instructions

(1) Start Up

a) Make sure the sample beam and reference beam are not blocked.

b) Push the POWER switch ON.

c) Wait 60 seconds for the system to initialize. the CHART EXPANSION 1 LED (default parameter) and SCAN TIME 12 LED (default parameter) will light.

(2) Setting the Starting Wave Number

a) Press the WAVE NUMBER control (The WAVE NUMBER LED will light.) The wave number the instrument is set at will appear on the display.

b) Press the PARAMETER ADJUST control to set the wave number to the desired value. The chart paper can reposition itself up to ± 1.0 cm during these adjustments. Press PARAMETER ADJUST

to move the grating to higher wave numbers. Press PARAMETER ADJUST

to move the grating to lower wave numbers. If the WAVE NUMBER LED is not illuminated, the chart will move together with the wave number.

(3) Selecting the Chart Expansion

a) Press the CHART EXPANSION CONTROL 0.5, 1, or 5 to select the chart expansions. The appropriate LED will light.

(4) Setting the Chart Paper

a) Press the CHART control (the CHART LED will light).

b) Press the PARAMETER ADJUST controls to move the chart paper left or right in one centimeter intervals until correctly aligned.

(5) Determining and Setting the Scan Time/Slit Program

a) Press the SCAN TIME "3" control to select a three-minute scan with wide slits (the SCAN TIME "3" LED will light).

b) Press the SCAN TIME "3" and "X4" controls to select a twelve-minute scan with wide slits. Wide slits are twice the width (in wave numbers) of narrow slits (the SCAN TIME "3" and "X4" LED will light).

c) Press the SCAN TIME "12" to select a twelve-minute scan with narrow slits (the SCAN TIME "12" LED will light).

When switching from wide to narrow or narrow to wide slits, while in the automatic slit mode, the instrument automatically scales the gain by a factor of 4 (the SCAN TIME "12" LED will light).

d) Press the SCAN TIME "12" and "X4" controls to select a forty-eight minute scan with narrow slits (the SCAN TIME "12" and "X4" LED'S will light).

(6) Checking the Gain (Use of the Baseline Control)

a) Make sure the monochronator is set to 4000 cm-¹.

b) Press the GAIN CHECK control (the GAIN CHECK LED will light). A unitless gain value will appear on the display and the pen will deflect on the recorder. If the gain is set correctly, the pen should deflect ten divisions (10% T).

c) If the pen does not deflect ten divisions, press the PARAMETER ADJUST control until a ten-division pen deflection is obtained. The instrument will normally initialize at the correct gain setting.

NOTE: The gain setting should normally be checked at 4000 cm-¹. The gain can be adjusted at a frequency within this region if the scan is to be made over a limited frequency region. It should not be adjusted in regions where atmospheric absorption occurs.

d) To adjust the baseline, with nothing in either beam, set the pen at 100% transmittance with the Baseline Control.

(7) Use of the Time Drive Control

a) Press the TIME DRIVE control (the TIME DRIVE LED will light). The chart paper moves at a rate determined by the CHART EXPANSION selected.

b) To cancel the Time Drive, press the TIME DRIVE control.

(8) Starting the Scan

After selection of the appropriate instrument settings, put the sample in the sample beam and press the SCAN control. The instrument automatically records the spectrum over the full wavelength range of the instrument.

(9) Ending the Scan

To stop a scan in progress, press the SCAN control.

Memory Load Operation

The Parameter Memory Accessory can be used to index to a wave number stored in memory, when installed in a 1300 Series Infrared Spectrophotometer. It can also be used to perform memory scans, repetitive scan overlays, sequential repetitive scans, and scans longer than 50 cm-¹. Single-beam mode operation is possible too.

(A) Loading Memory

1) To load memory, press the MEMORY LOAD CONTROL. The MEMORY LOAD LED lights and the instrument goes to the first wave number in memory. If no wave number has been loaded in memory, the instrument goes to 4000 cm-¹ default position.

2) If desired, change the CHART EXPANSION, SLIT PROGRAM, MANUAL SLIT, WAVE NUMBER, and GAIN.

3) Press the MEMORY LOAD control. The MEMORY LOAD LED will blink (go on and off). The instrument parameters selected are stored in memory and the memory location just loaded is displayed.

4) Repeat steps 1 through 3 to load up to 34 (thirty-four) memory locations. (Each time step 1 is initiated, the instrument will go to the next wave number stored in the next memory location. If no wave number is stored the display will read "0000".)

5) Press the MEMORY USE control, while the MEMORY LOAD LED is blinking, to remove the Memory Load mode. The instrument will go to the first wave number in memory then the Memory Load is erased.

6) The following example shows the procedure to load wave numbers 3700 cm-¹ and 1600 cm-¹ into memory.

a) Press the MEMORY LOAD control (the MEMORY LOAD LED lights).

b) Press the WAVE NUMBER and PARAMETER ADJUST controls and go to 3700 cm-¹.

c) Press the MEMORY LOAD control (the MEMORY LOAD LED blinks, 3700 cm-¹ is now stored in memory and "0001" is displayed).

d) Press the MEMORY LOAD control (the MEMORY LOAD LED lights).

e) Press the WAVE NUMBER and PARAMETER ADJUST controls and go to 1600 cm-¹.

f) Press the MEMORY LOAD control (the MEMORY LOAD LED blinks, 1600 cm-¹ is now stored in memory and "0002" is displayed).

g) Press the MEMORY USE control. The Memory Load is now erased. 3700 cm-¹ and 1600 cm -¹ are now in the memory locations 0001 and 0002.

(B) Erasing Parameters Stored In Memory

1) Press the MEMORY LOAD control (the MEMORY LOAD LED lights).

2) Press the MEMORY USE control until the MEMORY USE LED lights (there is a 2 second wait).

All memory locations are now erased and "0000" is found in each memory location. Default value 4000 cm-¹ is still stored in the first memory location.

(C) Performing A Memory Scan

1) Press the MEMORY USE control. The instrument goes to the first wave number in memory.

2) Press the MEMORY USE control again (the MEMORY USE LED lights). No parameters can be adjusted at this time. If the MEMORY USE LED is illuminated by accident, it can be put out by pressing the MEMORY USE control again.

3) Press the SCAN control to start the Memory Scan. A cross will be drawn at each wave number in memory. If X4 was selected, the pen traces % T at the 48 minute scan rate for a distance of 50 cm-¹. This occurs after the wave number in memory, instead of drawing a cross. After all the locations in memory have been scanned, a beep (sound) will be heard.

4) The following example shows how to perform a Scan when memory has been loaded.

a) Press the MEMORY USE control (the MEMORY USE LED lights). The instrument then goes to the first wave number in memory.

b) Press the CHART control, then the PARAMETER ADJUST control, to synchronize the chart paper with the wave number on display.

c) Press the MEMORY USE control (the MEMORY USE LED lights). No parameters can be adjusted at this time. If the MEMORY USE LED is illuminated by accident, it can be put out by pressing the MEMORY USE control again.

d) Press the SCAN control. The instrument performs a Memory Scan and beeps when finished.

(D) Removing the Memory Scan

To remove the Memory Scan, press and hold the Scan Control until a beep is heard.

(E) Indexing the Instrument to the First Wave Number in Memory

Press the MEMORY USE control. The instrument goes to the first wave number in memory. If no wave number has been loaded into the memory the instrument goes to the default value 4000 cm-¹.

(F) Stopping the Memory Use During Indexing

Press the MEMORY USE control.

(G) Performing A Repetitive Scan Overlay

The following example shows how a Repetitive Scan Overlay is loaded into memory and run. A scan of 3800 to 3750 cm-¹ was run. This mode is useful when time-dependent reactions are observed.

1) Press the MEMORY LOAD control (the MEMORY LOAD LED lights).

2) Press the WAVE NUMBER control (the WAVE NUMBER LED lights).

3) Press the PARAMETER ADJUST control and set the wave number to 3800 cm-¹.

4) Press the SCAN TIME/SLIT PROGRAM X4 control (the X4 LED lights).

5) Press the GAIN CHECK control (the GAIN CHECK LED lights and the gain setting is shown on the display). If a ten-division pen deflection does not occur, use the PARAMETER ADJUST controls to adjust the gain.

6) Press the MEMORY LOAD control (the MEMORY LOAD LED blinks, indicating the wave number 3800 cm-¹ has been loaded.

7) Press the MEMORY LOAD two times to store each additional scan of the 3800 to 3750 cm-¹ region to be performed (the maximum number of scans that can be done is thirty-four).

8) Press the MEMORY USE control while the MEMORY LOAD LED is blinking to remove the loading mode (the MEMORY LOAD LED goes off).

9) Press the CHART control (the CHART LED lights).

10) Press the PARAMETER ADJUST control to set the chart paper to the wave number on the display.

11) Press the MEMORY USE control (the MEMORY USE LED lights).

12) If the MEMORY USE LED stays on, press the SCAN control. If the MEMORY USE LED is not on, press the MEMORY USE control again (the MEMORY USE LED will light). Then press the SCAN control.

13) The Repetitive Scan Overlay will proceed (a beep then indicates when the procedure is complete).

(H) Performing a Sequential Repetitive Scan

The following example shows how a Repetitive Sequential Scan is loaded into memory and run. A 50 cm-¹ was repeated a number of times with each plot being separated by a 20 cm-¹ distance.

1) Press the MEMORY LOAD control (the MEMORY LOAD LED lights).

2) Press the WAVE NUMBER control (the WAVE NUMBER LED lights).

3) Press the PARAMETER ADJUST controls and set the wave number to 3900 cm-¹.

4) Press the CHART EXPANSION 1 control (the CHART EXPANSION 1 LED lights).

5) Press the SCAN TIME/SLIT PROGRAM X4 control (the X4 LED lights).

6) Press the GAIN CHECK control (the GAIN CHECK LED lights and the gain setting is displayed). If a ten-division pen deflection does not occur, use the PARAMETER ADJUST controls to adjust the gain.

7) Press the MEMORY LOAD control (the MEMORY LOAD LED blinks).

8) Press the MEMORY LOAD control again (the MEMORY LOAD LED lights and stays on).

9) Press the WAVE NUMBER control (the WAVE NUMBER LED lights).

10) Press the PARAMETER ADJUST control. Set the wave number to 3830 cm-¹ to separate the plots by 20 cm-¹. (Any value greater than 50 cm-¹ below the first wave number of the scan may be used for a different format.)

11) Press the X4 control (the X4 LED goes off).

12) Press the CHART EXPANSION 5 control (the CHART EXPANSION 5 LED lights).

13) Press the MEMORY LOAD control (the MEMORY LOAD LED blinks).

14) Press the MEMORY LOAD control again (the MEMORY LOAD LED lights and stays on).

15) Press the WAVE NUMBER control (the WAVE NUMBER LED lights).

16) Press the PARAMETER ADJUST controls and return the display to the first wave number (3900 cm-¹ for this example).

17) Press the CHART EXPANSION 1 control to return to the original chart expansion.

18) Press the SCAN TIME/SLIT PROGRAM X4 control (the X4 LED lights).

19) Press the MEMORY LOAD control (the MEMORY LOAD LED blinks). Two 50 cm-¹ plots from 3900 to 3850 cm-¹ are now loaded in memory.

20) Repeat Steps 8 through 19 to store each additional plot (17 scans is the maximum number that can be performed).

21) Press the MEMORY USE control (the MEMORY USE and MEMORY LOAD LED'S go off).

22) Press the CHART control (the CHART LED lights).

23) Press the PARAMETER ADJUST control to set the chart paper to the wave number on the display.

24) Press the MEMORY USE control (the MEMORY USE LED lights).

25) Press the SCAN control.

26) The repetitive sequential scan continues (a beep then indicates when the procedure is complete).

(I) Performing a Scan Longer than 50 cm-¹

(A maximum of thirty-four 50 cm-¹ scans can be chained together.)

1) Press the MEMORY LOAD control (the MEMORY LED lights).

2) Press the WAVE NUMBER control (the WAVE NUMBER LED lights).

3) Press the PARAMETER ADJUST controls and set the wave number to the desired value.

4) Press the SCAN TIME/SLIT PROGRAM X4 control (the X4 LED lights).

5) Press the GAIN CHECK control (The GAIN CHECK LED lights and the gain setting is displayed). If a ten-division pen deflection does not occur, use the PARAMETER ADJUST controls to adjust the gain.

6) Press the MEMORY LOAD control (the MEMORY LOAD LED blinks and "0001" stays on the display).

7) Press the MEMORY LOAD control again (the MEMORY LOAD LED lights and stays on).

8) Press the WAVE NUMBER CONTROL (the WAVE NUMBER LED lights).

9) Press the PARAMETER ADJUST controls and set the wave number to a value 50 cm-¹ below the first wave number selected.

10) Press the MEMORY LOAD control (the MEMORY LOAD LED blinks and "0002" is shown on the display). A 100 cm-¹ scan is now loaded in memory.

11) Repeat steps 7 through 10 to add additional 50 cm-¹ segments to the scan.

12) Press the MEMORY USE control (the MEMORY USE LED and MEMORY LOAD LED go off).

13) Press the MEMORY USE control again (the MEMORY USE LED will light).

14) Press the SCAN control to begin the scan.

(J) Single Beam Operation

Single Beam Operation is generally used to evaluate routine performance. Use the following steps to operate in the single beam mode.

1) Press the TEST button under the instrument cover; "ABCD" appears on the display.

2) Press the CHART EXPANSION 1 control; "BBBB" appears on the display for 2 seconds.

3) Block the sample beam completely and press the MEMORY LOAD control. The instrument is now in the single beam mode.

4) Press the Test button to exit from the single beam mode ("0000" appears on the display).

5) When operating in the Single Beam mode, the following controls work differently from their function during Double Beam operation. The controls and single beam functions are given below: