MTEC PAC300 User manual

1
MTEC PAC300
Photoacoustic Detector
Operating Instructions
August, 2023
MTEC Photoacoustics, Inc.
3507 Oakland St.
Ames, IA 50014 USA
Telephone: [phone]
www.mtecpas.com
[email protected]

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Table of Contents
1. First and Foremost: Three Key Precautions to Protect PAC300 from Damage
1.1 Protecting Microphone during Purging ………………………………............3
1.2 Caution to Avoid Breaking Window ……………………………………………….3
1.3 Protecting Window from Moisture Damage …………………………………..3
2. Unpacking
2.1 Unsealing the Hermetically Sealed Shipping/Storage Case ……………..3
2.2 Packing List …………………………………………………………………………………...3
2.3 Damage Inspection …………………………………………………………………………4
3. PAC300 Description
3.1 Introduction to the PAC300 ………………………………………………………………….4
4. Set-Up Directions
4.1 Insert Rear Lever …………………………………………………………………………….5
4.2 Mounting and Alignment of the PAC300 in the FTIR ……………………..…6
4.3 Electrical Connections …………………………………………………………………….9
4.4 Purge Gas Connections …………………………………………………………………..10
5. Operation
5.1 Preamplifier Gain Control …………………………………………………………..….10
5.2 Rear Lever Operation …………………………………………………………………….11
5.3 Sample Cup Loading ……………………………………………………………………..11
5.4 Sample Cup Insertion …………………………………………………………………..…13
5.5 Purging ………………………………………………………………………………………....14
5.6 FTIR Spectrum Acquisition Parameters ………………………………………..…14
5.7 Test Procedure ……………………………………………………………………………….15
5.8 Acquiring and Normalizing a Sample Spectrum …………………………..…15
5.9 Advanced Methods of Photoacoustic Spectroscopy ……………………...16
5.10 Storage of the PAC30 ……………………………………………………………………16
6. User Adjustments and Servicing
6.1 Setting the Sample and Reference Cup O-ring Seal Compression …..17
6.2 Window Replacement ……………………………………………………………………17
7. Service Assistance
7.1 Returning Units for Factory Servicing ……………………………………………..19
7.2 Foreign Returns ……………………………………………………………………………….19
8. Product Warranty and Disclaimer …………………………………………………………………..….20

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1. First and Foremost: Three Key Precautions to Protect PAC300 from Damage
1.1 Protecting Microphone during Purging
Purging with zero grade helium gas is used to enhance the sensitivity of photoacoustic
measurements and to reduce the moisture level in the sample chamber which
superimposes a water vapor spectrum on the sample spectrum and also interferes with
condensed sample signal generation. However, a too high gas flow rate can easily damage
the PAC300’s sensitive microphone. Accidental high flow rates may occur when gas valves
are being opened or adjusted. The PAC300 microphone is protected from gas flow surges
as long as the rear lever is in the SEAL position.
1.2 Caution to Avoid Breaking Window
Do not place samples in the brass sample cup that extend above 1 mm from the top of the
cup. Samples that extend above the top of the cup will break the PAC300’s window.
1.3 Protecting Window from Moisture Damage
The PAC300’s KBr window is moisture sensitive. The window can be protected from
moisture damage by storing the unit in its hermetically sealed case with a 10 g packet of
indicating silica gel ( http://silicagelpackets.com/indicating-silica-gel-packets/indicating-
silica-gel-packets/10-gram-indicating.html ).
2. Unpacking
2.1 Unsealing the Hermetically Sealed Shipping/Storage Case
In cold weather, it is advisable to let the case warm up for 24 hrs. before opening to
prevent moisture condensation on the KBr window.
2.2 Packing List
All PAC300 photoacoustic accessories include:
1. PAC300 with focusing mirror and KBr window.
2. Black handled sample holder (inserted in PAC300) with brass sample nest, five
small and five large removable sample cups, five nest spacers to elevate samples,
sample cup fixture and funnel, tweezers and Allen wrench to adjust cup o-ring
compression.
3. Carbon reference sample mounted in black handle.
4. Liquid crystal for imaging IR beam position.
5. Helium flow meter.
6. Hermetically sealed shipping/storage case

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Some accessories may also include one or more of the following:
1. FTIR specific baseplate mounting.
2. Desk-top power supply.
3. Glassy carbon phase reference.
4. FTIR specific connection cable(s).
5. PAC300 elevation adjustment shims.
6. FTIR purge coupling.
7. SH003 and/or SH004 options.
2.3 Damage Inspection
Please examine items for evidence of shipping damage. Report any damage to the carrier
and to MTEC for direct purchases or the reseller that shipped the accessory.
3. PAC300 Description
3.1 Introduction to the PAC300
The PAC300 enables direct measurement by photoacoustic detection of
optical absorption spectra of s o lid s and semisolids and is primarily used in
FTIR spectrometers:
http://www.mtecpas.com/Docs/Photoacoustic%20Technology%20Overview.p
df .
The detector can be used for a wide range of measurements as described in
the applications liter atur e and literature bibliography:
http://www.mtecpas.com/applicationslibrary.html ,
http://www.mtecpas.com/Docs/FTIR%20PAS%20Bibliography%20Draft%205.pdf .
The PAC300 can also be used with nonvolatile liquid and noncorrosive gas samples which
are not toxic.
The PAC300 is designed for ease of use. It mounts in the s t a n d a r d FTIR slide-
mount fixture or on FTIR specific baseplates. Sample changing, purging,
and sealing ar e controlled by a single lever, detector preamplifier gain is
controlled by a 12 position switch on the detector, and the detector is
powered either by the FTIR or by a 115/230 V, 60/50 Hz desk top power supply
with an international standard IEC 320 input connector. This allows the power
supply to be used with appropriate cord sets for any country of the world .
Inserts into FTIR Slide Mount
Inserts into FTIR Sample compartment
PAC300 for slide mount fixture (left)
or baseplate mounting (right).

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4. Set-Up Directions
4.1 Insert Rear Lever
The stainless steel rear lever is packed separately from the PAC300 in the shipping case
and should be inserted into one of the three slots on the back of the PAC300. Use the slot
that allows the lever to rotate most conveniently in your FTIR through the 90 degrees of
rotation necessary to purge and seal the sample. Note that the sample holder can be
inserted from either side of the PAC300 to accommodate both right-to-left and left-to-
right beam directions in different FTIRs.
Purge Inlet
Sample Holder
Rear Lever
FTIR Purge
Coupler
Baseplate

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4.2 Mounting and Alignment of the PAC300 in the FTIR
The PAC300 is either mounted on an FTIR specific baseplate or in the standard sample
slide mount found in all FTIRs. Baseplate and slide mounted PAC300s are prealigned and
usually will not require the adjustments described below.
Alignment can be checked using the i nfrared heat sensitive liquid crystals supplied
with the PAC300.
Lever
Slots
Color Change Indicates
FTIR beam focal spot. If the
spot is centered in the cup,
the PAC300 is aligned.
PAC300 needs to be moved
horizontally perpendicular
to the IR beam to center the
spot in sample cup.
IR Beam
1
2

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In order to check alignment, place a liquid crystal in the sample cup following
these directions in its package:
Heat Sensitive Liquid Crystals (HSLCs)
The HSLCsare usedto alignthe photoacoustic detector in the FTIRby imaging the focal spot of the IR beam in the sample
cup. Each HSLC covers a slightly different ambient temperature range. The one best suited for a given ambient
temperature should be selected by trying each. Place a HSLC in the large sample cup supported on the foam spacer. A
brass spacer should be used under the foam to elevate the HSLC to a point near the cup rim. The heat sensitive side of
the HSCL can be identified by finger touch induced heating. The detector position should be adjusted to center the
focal spot image in the sample cup. See the Instruction Manual for additional information.
Then block the infrared beam and insert the sample holder with the li qu id
crystal into the PAC300. Fully open the aperture of the FTIR. Elevate the crystal
by moving the rear lever to the CLOSED PURGE position. Remov e the beam
block, wait several seconds, remove the sample cup, and examine the image
pattern before it fades as the temperature falls.
The types of images that may be observed are shown above. Image 1
indicates ideal alignment. Image 2 shows s ide - t o- s ide misalignment. This can
be corrected by moving the PAC300 perpendicular to the beam in the
direction opposite to the misal i gnment direction. The side-to-side
adjustment can be made as shown below either by loosening the screws on the
baseplate and sliding the PAC300 side-to-side or by adjusting the slide plate
relative to its mounting yoke.
Image 3 indicatesthat the PAC300 needs to be raised. The height of
baseplate mounted PAC300s can be adjusted with the screws that support
the accessory on the baseplate as shown below.
PAC300 needs to be
moved vertically to
center the spot in sample
cup.
3
Shims for height adjustment
Side-to-side adjustment
Side-to-side adjustment

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In the case of slide mounted PAC300s, some FTI R slide fixtures have provision for
height adjustments while others do not. If th e r e is no adjustment provided
on the FTIR, height adjustments are made by placing, as shown above, small
shims provided with the detector between the PAC300 s lide mount and the
yoke coupling plate. Adding shims lowers the detector and moves th e image
in the direction of the front of the PAC300 .
In some cases it may be desirable with slide mount fixtures to support the
PAC300 directly on the FTIR’s or other instrument’s baseplate. Four 5-40
thread screws can be used as adjustable legs as shown below.
If slide mount fixture’s position is designed to be adjustable in the direction of the IR beam
, it may be observed that the infrared beam image on the liquid crystal is large
and weak. This may be caused by the PAC300 not being positioned properly relative
the IR beam’s focal spot which is normally at the midpoint of the beam’s path through the
FTIR's s a mple compartment. The PAC300’s optics require that the PAC300’s
slide plate be coincident with the FTIR’s focal plane with the hole in its slide
plate centered on the focal spot of the FTIR. To achieve this, the slide mount’s
position can be adjusted while watching the PAC300’s interferogram signal to
maximize it.
This nut is one of four used to
raise or lower the PAC300 on
a baseplate mounted unit.
Four 5-40 Screws Support
the PAC300 and allow for
height adjustment.
FTIR’s focal spot

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4.3 Electrical Connections
The PAC300 is powered either by the FTIR or an MTEC desktop power supply. The power
and signal cables are connected to the vibration isolated part of the accessory after first
being secured to the stationary part to avoid transmitting mechanical vibrations to the
PAC300’s sensitive microphone.
The desktop power supply has +15 and -15 Volt outputs and connects to either 115V 60 Hz
or 230V 50 Hz power lines. It has an IEC 320 power cord connector and an RJ9 output
connector.
The PAC300’s preamplifier gain is adjustable in 12 steps from 2X to 10,000X to
accommodate samples with different thermal properties and FTIR mirror velocities.
Power In
Signal Out
Gain Switch
On-Off switch
120/230 Volt
switch

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4.4 Purge Gas Connections
Purging with Zero Grade Helium increases the signal by a factor of 2 to 3 and helps to exhaust
moisture and CO2 from the sample chamber. A two stage gas regulator valve should be
connected to a helium tank with its output connected to the MTEC flow meter. The
flowmeter output is connected to the inlet of the stationary part of the PAC300. Its outlet is
connected to the vibration isolated sample chamber. Consult Section 5.5 before purging the
PAC300.
5. Operation
5.1 Preamplifier Gain Control
A twelve position switch controls the gain as fo llows :
step# 1
2
3
4
5 6 7 8 9 10
11
12
gain 2
5
10
20
50 100 200 500 1000 2000
5000
10,000
factor
The gain should be set high enough to give an inter f er ogr a m amplitude of
several volts but not too high to either cause preamplifier clipping (<20V pe ak -
to-peak) or to overloadthe FTIR's A to D converter.
Higher gains are used for higher FTIR mirror velocities because the signal
amplitude decreases as modulation frequency increases. Higher gai ns are
also used when sample spectra are being acquired relative to c a r bon
reference background spectra because totally absorbing carbon gener a tes
higher signal amplitudes than partially absorbing samples whichusually a l s o
have higher thermal mass.
To Gas
Cylinder
Line Pressure
Tank Pressure
Control Flow Rate
Only with this Valve
Leave This Valve
Always Open
Rear Lever Always In the SEAL
Position When Adjusting Valves
Flow Rate 10cc/s or Less

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5.2 Rear Lever Operation
The rear lever rotates over an angle of 90 degrees to elevate the sample hol d er
into the detector's sample chamber and to compress the holder’s o-ring to
seal the chamber. The lever also automatically controls the purg e valve during
the 90 degree rotation. A detent snap device indexes four rota ti onal positions
over the 90 degree rotation. These are the OPEN, OPEN PU RGE, CLOSED
PURGE, and SEAL positions which are shown schematically on the detector's
sides for easy reference during operati o n.
In the OPEN position the sample holder may be withdrawn or i nserted
for sample cha n g e .
In the OPEN PURGE position purge gas flows through the sample chamber and
out the bottom because the sample holder o-ring is not s e ale d .
In the CLOSED PURGE position purge gas flows past a hole leading to the
sample chamber but not through it. Consequently, purging is slower but
there is no flow over the sample whichmight blow powders out of the cup.
In the SEAL position the sample chamber is sealed and spectra may
be acquired. The purge gas still can flow but is sealed from the sampl e
chamber so the microphone is protected from any surges in the gas flow that
might occur when gas valves are being opened, adjusted or closed.
5.3 Sample Cup Loading
The PAC300 is supplied with five small and five large samp le cups and five
brass spacer inserts. The cups and inserts fit into a b r a ss nest which is
attached to the black sample holder handle. The slot in the brass part
should be kept oriented perpendicular to the handle length. The o-ring seals
the detector when the lever is rotated fully to the SEAL location and must be
kept clean.
v
Brass nest rim
Sample cups
Sample cup
elevation spacers

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To avoid breaking the detector window, do not place anyth i n g which
extends higher than the rim of the brass nest because when the rear
lever is rotated to the SEAL location, the rim is located just below the
detector window. An yth i ng extending above the rim will be forced into
the window and break i t .
Samples, depending on size, are placed in the small sample cups or in the
large brass cup holder (in the latter case with or without a large sample cup).
The brass spacer inserts ar e used to eliminate excess volume in the sample
cup. A higher signal level is consequently obtained because the signal is
inversely proportional to the g a s volume. The inserts and sample levels in
cups should be chosen so that th e sample is approximately 1 mm or more
below the brass cup holder rim. T h i s distance allows the photoacoustic signal
to be generated in the gas withou t thermal interference by the window
above the sample.
Course samples ma y be placed in cups using tweezers. Fine powders may
be loaded with the funnel by first placing cups either directly in the brass
nest or in the slotted cup fixture and then placing the funnel in position .
An alternative approach is to scoop powders from storage containers
with the sample cups held by tweezers and then use the slotted cup fixture
to align the tweezers in order to facilitate easy insertion of the cu p into the
brass cup holder. Be careful not to spill samples onto the o-ring. On ly enough
sample to cover the bottom of the sample cup is necessar y .
Samples (both micro and macro)that evolve H20 vapor should be r un
with a desiccant in the sample chamber to avoid vapor bands in s pe c tr a.
Magnesium perchlorate is a very effective desiccant and can often be used
safely. This chemical is, however, a strong oxidizing agent and may create a
hazard when used in close proximitywith certain samples. It is the operator's
responsibility to consult and observe appropriate safety in fo r m at io n

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The desiccant is placed in a large sample cup. This cup is inserted in to the
brass holder , a slotted spacer insert is placed over the desi ccant cup, and the
slots are aligned to permit gas circulation between the desi cca nt and sample
cups. Finally, the sample is put in a second cup which is inserted above the
desiccant cup. Never leave desiccant in the sample cup when the detector
is not sealed because a corrosive liquid will form as moisture is collected
by the desiccant from the room a i r. If the detector is stored for an extended
time, check the status of the desiccant periodically.
There are several effective approaches in addition to the desiccative
cup, which may be used alone or in combination to reduce vapor b a n d
interference from a sample. These approaches include vacuum and/or oven
drying of samples prior to measurements, reduction of the amount of sampl e
placed in the cup, dry gas purging (zero grade helium), and spectral
subtraction. In terferen ce bands may also be present due to residual vapors
in the detector from the previous samples, degassing of internal
components, or from the storage bo x. These bands can be readily reduced to
an acceptable level by purging. Note that bands due to vapor absorption
in the detector are always p o s i tive pointing whereas vapor absorption in
the spectrometer produces negati ve pointing b a nds.
5.4 Sample Cup Insertion
The sample cup can be inserted from either side of the detector si nce
different sides of the detector are accessible with different FTIRs. The
sample holder is ready to be slid into place for elevation into th e sample
chamber and sealing by the rear lever.
Desiccant
Slotted Spacer

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5.5 Purging
Purging increases the signal level by approximately a factor of 2 to 3 and
reduces moisture in the sample chamber. Care must be taken in purg i n g the
detector, however, to avoid large pressure fluctuationsthat could damage the
microphone.
Use clean dry helium gas such as "zero grade". Only the primar y
pressure regulator valve on the gas cylinder should be used to control the
flow rate as indicated in Section 4.4. If the regulator has a second valve at
the regulator output set this valve to the full open position and leave it so
set. Keep the detector lever i n the SEAL position whenever the gas is being
turned on or off and when the flow is being adjusted. These are the times
when pressure surges are most likely to occur and the SEAL position isolates
the microphone.
Use a flow rate of 10-20 cc/s for most sa mples.
For fine powders just fill sample cups with a thin layer. To insure that the
powder cannot be blown out of the cup during purging, just before inserting the sample
into the PAC300, reduce the helium flow to zero as per Section 4.4, insert the sample cup
into the PAC300 and rotate the rear lever to the SEAL position. Now increase the helium
flow to 5 cc/s and rotate the rear lever just to the Closed Purge position and wait 30 s.
Next rotate the rear lever to the SEAL position and collect the spectrum of the sample.
Reduce the helium flow to zero, rotate the rear lever to the OPEN position, and remove
the sample. Rotate the rear lever to the seal position, set the helium flow to between 5
and 10 cc/s, and rotate the rear lever to the OPEN position. Prepare the next sample to be
loaded and repeat the sample insertion steps given above starting with reducing the
helium flow to zero.
Ten seconds purge time in each of the purge locations is usually suffi ci ent.
Longer times may be necessary if considerable moisture is p r e s e n t.
Leaving the detector sealed with desiccant under the sample cup for a n
extended time during measurements is the best way to remove the last traces
of moi s ture.
When the detector is initially purged with helium there will be a
gradual decrease in signal amplitude as helium exchanges with air in th e
rear volume of the microphonethat is connected to the sample chamber by a
fine capillary. This drift will be minimized if helium is kept sealed in th e
detectorat all times. The signal will also gradually decrease due to di ff u s i on of
helium at the o-ring seals. Signal drift can be eliminated by purging with dry
nitrogen but the signal enhancement of helium is lost.
5.6 FTIR Spectrum Acquisition Parameters
For general use, the followingare usua lly appropriate:
1. Minimum mirror velocity tha t is stable
2. Maximum source ap e r tu r e
3. Resolution of 8 cm
-1
4. Scan number depending on signal-to-noise ratio

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5.7 Test Procedure
1. Remove the red protective cap, place the carbon black reference (Fi g .
4.11) in the detector and purge the detector, if desi red.
CAUTION. Do not allow anything to contact the black absorber
surface of the carbon reference. It is e a sily damaged. Keep the
red protective cap on the carbon bl ac k reference when not in use.
Do not leave the carbon black reference in the detector when a
backgroundspectrum is not being acquired.
2. Adjust the detector gain for a peak-to-peak amplitude of several
volts. This will assure t ha t the preamplifier is not clipping (clipping occurs
at approximately 20 volts ma x i mum peak-to-peak) and that the FTIR input is
not overloading.
3. If the PAC300detector initially does not produce a signal, di sc onnect and
then reconnect the telephone connector on the white cable located next to the
detector's gain sw itch.
4. Acquire two single beam spectra of 8 scansat 8 cm-1 resolution and an
OPD mirror velocity of 0.16 cm/ s with the MTEC carbon reference . If the FTIR
spectrometer does not have an OPD velocity of 0.16 c m /s substitute the
closest availa ble .
5. Ratio the two single beam spectra to obtain a 100% line. P e ak - t o- peak
noise should be 0.4% or less i n t he r a ng e f ro m 19 0 0 t o 2 1 0 0 cm-1 for
most FTIR i nstruments using a helium purge. The peak-to-peak noise will be
found to increase if a higher mirror vel o ci t y is used due to the slow time
response of photoacousti c signal gener a tion .
5.8 Acquiring and Normalizing a Sample Spectrum
1. Load the sample (see 5.3 and 5.4) and purge (see 5.5) the detector, if desired.
2. Set the detector gain to provide a signal level which is less than or equal to what was
used for the carbon black spectrum (see 5.7) and acquire the sample spectrum (see 5.6).
3. Divide the sample spectrum by a carbon black spectrum in order to obtain an
absorbance like spectrum of the sample. Some FTIR’s have parameter settings to
automatically ratio the sample to reference spectra and display it in photoacoustic units.
Do not touch
black surface!

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5.9 Advanced Methods of Photoacoustic Spectroscopy
Advanced photoacoustic spectroscopic methods utilize both the magnitude and phase of
the photoacoustic signal often to investigate depth varying composition in the form of
layers or gradients. Glassy carbon is the best phase reference material for such
investigations.
A general overview of some interesting advanced applications is available here:
http://www.mtecpas.com/Docs/Photoacoustic%20Technology%20Overview.pdf.
The PAC300 can be used to study samples with depth varying composition in the form of
layers and gradients over depth ranges of a few tens of microns. If deeper depths are of
interest, MTEC’s MicroLap device (http://www.mtecpas.com/microlap.html) can be used
on planar samples. For further information in general see:
http://www.mtecpas.com/Docs/MicroLap%20Technology.pdf
http://www.mtecpas.com/Docs/MicroLap3.pdf
http://www.mtecpas.com/Docs/Introduction%20to%20Photoacoustic%20Spectroscopy%2
0with%20Step%20Scan%20and%20Constant%20Velocity%20Scan%20FTIR%20Spectromet
ers.pdf
http://www.mtecpas.com/Docs/BCG.pdf
http://www.mtecpas.com/Docs/MicroLap1.pdf
http://www.mtecpas.com/Docs/MicroLap2.pdf
MTEC offers two options with sampling heads for sequential diffuse reflectance,
photoacoustic absorbance, and transmittance measurements (Option SH003) and for
microsamples in the form of single particles and fibers (Option SH004). For further
information see:
http://www.mtecpas.com/Docs/MTEC%20Sampling%20Head%20Options.pdf
http://www.mtecpas.com/Docs/Prac%20Guide%20to%20FTIR%20Photoacoustic.pdf
5.10 Storage of the PAC300
The PAC300’s KBr window is moisture sensitive. The window can be protected from
moisture damage by storing the unit in its hermetically sealed case with a 10 g silica gel
desiccant pack with indicator to tell when to change to fresh desiccant:
http://silicagelpackets.com/indicating-silica-gel-packets/indicating-silica-gel-packets/10-
gram-indicating.html

17
6. User Adjustments and Servicing
6.1 Setting the Sample and Reference Cup O-ring Seal Compression
Two set screws control the compression of the sample cup's o-ring sea l . These
screws must be adjusted symmetrically to extend the same distance in order to
avoid cocki n g the o-ring flange relative to the detector body. When properly
adjusted, the sample holder handle should not be moveable side-to-side relative
to the housing when the rear lever is in the SEAL p o s itio n .
6.2 Window Replacement
MTEC offers KBR, quartz, CsI, KRS5, and Polyethylene windows. It is
recommendedthat the detector be returned to MTEC for w i ndow replacement.
If the user prefers to replace the window, follow the fol l o w ing di recti o ns.
Disconnect the power and signal cables and the purge line.
Loosen the top set screw, remove the two top slide plate screws and the attached
part which clamps the cables.
No side-to-side motion in
rear lever SEAL position
Loosen

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Loosen the upper vibration isolator nuts and back off the screws as shown to
allow the detector to be lifted off the lower vibration isolation platform.
The detector’s mirror can now be removed by unscrewing its two attachment
screws to expose the four screws of the window’s o-ring compression plate.
Remove
Loosen

19
Once these screws are removed using a ball point Allan wrench, the plate can be
lifted off and the window replaced (diameter=18mm, thickness=3mm). Great care
must be taken in tightening the screws to compress the window o-ring. The
screws must be tightened in very small equal angle increments with a light touch
to avoid cracking the window. Carefully tighten the fou r compression screws to
compress the o-ring while keeping an equal gap on a ll sides between the
compression plate and the detector housing. The detector should be
reassembled by reversing the disassembly steps.
7. Service Assistance
7.1 Returning Units for Factory Servicing
Please contact MTEC for authorization prior to shipping any items for repair.
(MTEC email: [e-mail], telephone: [phone]; telefax: 1-515-292-
7974.) A ll transportation charges and insurance are the customer's
responsibility. A purchase order number must be provided before repairs will be
made. (See also Section 8 for Product Wa rra nty . )
Package the return carefully,securing all parts to prevent dama g e
during transit. Seal the empty sample cup in the detector. Send the
entire system including powersupply and ca b les.
Shipping address for returns: MTEC P h otoacousti cs, Inc.
3507 Oakland St r eet
Ames, Iowa 50014 U. S.A.
7.2 Foreign Returns
If possible, ship the package via a courier, such as Federal Express, who will act
on behalf of MTEC as a customs broker. This simplifies the return, expedites
clearance through U.S. Customs, and saves extra frei g h t forwarder costs to
MTEC which are billed back to the customer. Prepay the air waybill through to
Ames, Iowa. Consign to the shipping address above, and list MTEC's telephone
number (515-292-7974). To avoid co mp lic ations and delays, label the shipment
"free domicile." This simplifies U.S. C u s t o m s clearance. A copy of an invoice
showing the total value is required fo r customs. This invoice must state the
value, that the product was "Made i n the U.S.A." and is a "Returned American
Product for Repair Only." Ple a s e follow your local shipper's instructions
concerning all shipping r e qu ir eme n ts . If the return is made through a freight
forwarder, be sure the freight i s prepaid to Ames, Iowa, if possible, or at least
to Des Moines, Iowa. Use the "free domicile" declaration to avoid complications and
de la ys .

20
8. Product Warranty and Disclaimer
PRODUCT WARRANTY
MTEC Photoacoustics, Inc. warrants the Model 300 Photoacoustic Detector and its accessories
to be free from defects in material or workmanship and to operate to published specifications
under normal use, for a period of one year from the date of original shipment. No other
warranty is expressed or implied. If examination by MTEC Photoacoustics, Inc. discloses a
product defect, obligation is limited to repairing, replacing, or giving credit for the purchase
price, at our option. KBr windows, carbon black references, batteries, Option SH003 absorber
elements, and Option SH004 tungsten needles are not warranted. MTEC Photoacoustics is not
liable for any consequential damages or for any damages which might occur during vacuum
and/or bake out operations. Components other than those manufactured by MTEC
Photoacoustics, Inc., including microphones will carry the original manufacturer's warranty. All
transportation charges on items returned are the customer's responsibility. Contact MTEC
for authorization prior to returning any items for warranty claims.(See Section 7.)
PRODUCT DIS CLAIMER
MTEC Photoacoustics, Inc. will not assume responsibility fo r any damages to
persons or to property due to the operation of or t o results obtained with the
MTEC Model 300 photoacoustic detector system.
Loosen