Quantek 901 User manual
BEFORE YOU BEGIN
Thank you for your purchase. Before you
begin using the Model 901, please review the
following tips and precautions. 90% of repairs
are due to the issues outlined below:
Use a filter on the tip of the sample probe.
This prevents liquid intake.
Do not charge (or plug in) the instrument if
you install alkaline batteries.The charger
cannot tell the difference between
rechargeable and alkaline batteries. The
alkaline batteries will melt and/or explode if you
attempt to charge them!
The 901 is designed to be charged overnight,
and then unplugged during use.
Turn it off at the end of the day and plug it
in. If you leave it on, and plugged in, the
charger will stop after four hours, and the
analyzer batteries will deplete.
This is a frequent issue when operators leave it
on, and plugged into the charger, on a Friday.
When they come back Monday the analyzer is
dead and needs to be recharged.
Store the unit in a clean, dry location at the
end of the day/shift. Cleaning chemicals
commonly used in food production facilities can
corrode the circuitry in the unit.
GENERAL DESCRIPTION
The Quantek Model 901 is a battery-operated,
portable oxygen analyzer used for the
measurement of oxygen in packages, gas
streams, containers, and hundreds of other
applications.
INITIAL SETUP
The analyzer arrives with fully charged
batteries. Perform this procedure to
compensate for changes in elevation,
temperature, and/or humidity:
1) Turn the instrument on.
2) Remove the needle cover (or sheath).
3) Press the pump button –the reading will
go down temporarily.
4) Once the reading stabilizes, adjust the
span so that the reading is 20.9%.
It is recommended that you perform this
procedure at the beginning of each day. The
amount of oxygen in a room is always 20.9%,
regardless of ventilation or number of people
breathing nearby.
While humidity has a very small effect on O2
concentration, this effect is very minimal. At
100% relative humidity, the O2concentration in
air is about 20.4%.
Changes in elevation will also affect your initial
O2 reading. If the analyzer is calibrated for
sea level, and you bring it to 5000 feet above
sea level, you may notice the starting O2
concentration shows 17.9%. This is normal –
repeat the “initial setup” procedure so that the
instrument reads 20.9%.
UNDERSTANDING THE ADJUSTMENTS
The operating controls and adjustments
include power switch, pump switch, span, zero
and pump time adjustments:
SPAN: Use this on the side of the instrument
to adjust the analyzer to 20.9%. Press the
pump button, let the reading stabilize, then
adjust to 20.9%. You should do this once a
week, or if the instrument’s altitude has
changed. You should wait until the pump has
stopped, and the reading has stabilized, before
adjusting the span.
ZERO: This should generally not be touched.
See the section on checking the zero.
PUMP TIME: Use this to set the pump time. 5
seconds is ideal, but if your application,
package, or container has limited headspace,
you can set it to 3 seconds. Use a longer
pump time if the sensor is responding slow.
If you ever need to run the pump for longer
than 12 seconds, you can hold the button
down. This is rare, and would only be
applicable to situations where you might not
have the probe positioned properly to get a
good reading.
When turning the PUMP TIME adjustment:
COUNTERCLOCKWISE = SHORTER
CLOCKWISE = LONGER
PRECAUTIONS
Follow these other guidelines to prevent
damage:
1. Do not immerse in water or spray water
on the unit.
2. Do not drop the unit.
3. Store the unit in a clean, dry location at
the end of the day/shift. Cleaning
chemicals commonly used in food
production facilities can corrode the
circuitry in the unit.
4. Do not operate the unit while plugged in
–it is designed to be operated from the
batteries.
5. Be sure to check the battery polarity (+
and -) if you decide to swap out
batteries.
RECHARGING ANALYZER
To charge the analyzer, shut it off and leave it
plugged in to the charger. If you need to use it
right away, you can substitute alkaline AA
batteries, but again –DO NOT CHARGE THE
UNIT WITH ALKALINES INSTALLED!
The charger will go from solid orange, to
blinking orange, to fast blinking green, to slow
blinking green, to solid green. Your charger
may look different.
Note: These batteries are NiMH 2600 mAh
AAs. The total time to charge the analyzer fully
from 0-100% charge is approximately 2-3
hours.
The rechargeable batteries are high quality,
low self-discharge batteries. If you do need to
replace them, any rechargeable NiMH or
NiCad batteries can be used. Mixing brands is
not advised.
IF YOUR CHARGER IS DAMAGED:
Contact us for a replacement charger. In the
meantime, use alkalines.
If you absolutely must purchase a charger
locally, the specifications are: 2.5mm barrel,
center +. Most NiMH chargers will work, just
be sure to use a charger that is designed for 4
AA NiMH cells. Most NiMH chargers will work
for a range of AA quantities (i.e. 2-10 cells).
Please note: you will void your warranty if you
use a non-Quantek charger.
OPERATION SUMMARY:
1. Insert a particulate filter onto the end of the
sample probe. If you are testing through a
septum, or a package, you’ll want to use a
needle at the end of the probe. If you are
testing a gas stream, or a chamber, you may
want to use a blunt needle.
2. Press the POWER switch to start unit. No
warm up is required.
3. Press the PUMP switch. The pump will
come on for approximately 2 to 12 seconds
and pull room air into the sensor through the
syringe needle and filter. Note that the meter
reading will decrease slightly when the pump is
on. This is normal due to the slight vacuum
created in the sensor when the pump is
running. Wait approximately 10-12 seconds
(after the pump has stopped) for the reading to
stabilize. Room air should give a reading of
20.5 to 21.3 % oxygen. Adjust the oxygen
span to 20.9% if you’d like.
NOTE: You only need to perform step three
once a day –at most.
4. For non package applications –place the
probe in the area you’d like to measure.
Depress the PUMP switch and wait for the
reading to stabilize (12-18 seconds). Leave the
needle in the gas stream until a stable reading
has been obtained.
NOTE: Make sure that you have the blunt tip
needle placed in a location where ambient air
cannot be drawn into the probe.
To see examples of package testing, use the
following URL:
www.quantekinstruments.com/901support/
CALIBRATION OVERVIEW
The factory calibration schedule is two years
after initial purchase, and every year thereafter.
Customers who are comfortable self-calibrating
can use the procedure below.
Since the response of the oxygen sensor is
very linear (especially between 0.0% and
20.9%), checking the zero point and the span
point are sufficient for excellent accuracy.
Factory calibration includes a full checkup of all
components (such as the pump, sample probe,
circuit board, etc) and leak test of the system.
SELF-CALIBRATION: O2 SPAN
Accurate SPAN calibration of the unit can be
checked at any time by sampling room air,
which should give a reading of 20.9% oxygen,
plus or minus 0.3%. If the reading is off, it can
be set by adjusting the SPAN potentiometer,
located on the side of the unit, with the flathead
screwdriver supplied.
Significant changes in elevation will require
resetting the span calibration –for example, if
you take the instrument from sea level to
Denver, it will read 17.9%.
The amount of oxygen in a room will not vary
much –even in a closed building with many
people. However, if you ever want to be sure,
you can set the span using outside fresh air.
SELF-CALIBRATION: O2 ZERO
The zero setting of the O2channel is very
stable, and will change little even over a period
of several months. Although usually not
required, The O2ZERO reading can be
checked one of two ways:
1) BEST METHOD –
We also now include an orange tube for
calibration which you can insert into a tube of
flowing gas:
Also, make sure that the nitrogen has been
flowing for at least 30 seconds to flush out any
other air that may have been in the tubing.
Press the PUMP button, drawing in the flow .
The zero will read 0.0, plus or minus 0.1% O2.
If the reading is not in this range adjust the O2
ZERO potentiometer as needed. Several turns
will be needed to see any movement in the
reading, as the adjustment is not very
sensitive. This adjustment should be done
carefully because it will affect all readings, and
it must be done with N2in the sensor.
2) OKAY METHOD If you keep the flow very
light, you can flow nitrogen directly into the
sample probe. While this is the easiest method
to zero the instrument, it is critical that you
make a good connection with the tubing.
3) LAST RESORT METHOD
If a source of pure N2(or other zero oxygen
gas) is available with an outlet flow, turn it on
with a robust flow and place the sample probe
(with needle attached) straight into the tube
from which the flow is generating –but do not
create a tight seal. Make sure the nitrogen is
flowing at a high rate, so that when you press
the pump button, you are not drawing in room
air.
This is risky, though, because it is very easy to
draw room air in as the needle is only about
1.5 inches long. This method works better if
you have as long a needle as possible.
NOTE ABOUT THE ZERO ADJUSTMENT
This adjustment should be done carefully
because it will affect all readings, and it must
be done with N2(or any other zero gas) in the
sensor.
Take note that the “electronic zero” of the
sensor and electronics is very stable, with
typical variance of less than 0.1% O2over a
period of 12 months.
COMPLETE SYSTEMS TESTING
To ensure that the complete unit is working
properly requires periodic testing of the unit
under controlled conditions. Factors which can
affect accuracy include calibration, pump
function, electronic functions and leak-
tightness of all the parts used for sampling,
including the needle, filter, sample probe,
tubing, fitting, internal tubing and valve. A
simple, periodic test can determine proper
operation. With the needle and filter installed,
simply perform the zero test described in the
previous section and the unit should read zero.
With the needle still in the bag, operate the
pump several times. The reading should not
change.
If there are leaks in any part of the system, the
readings can be inaccurate on the high side
because of air leaking in. If a leak is suspected,
perform this simple test: fill a bag with nitrogen
and check the zero reading as before with 2-3
pump cycles. Keep the needle in the bag.
Next, compress the bag by hand (with the
pump off), which will force more sample
through the tubing into the sensor. This should
yield the same reading as sampling with the
pump, if there are no leaks. With this positive
pressure, air cannot leak into the system with
any leaks which may be present. If the reading
goes lower, it indicates a leak somewhere
which should be corrected.
PUMP TIME
The pump run time can be increased or
decreased as needed by adjusting the PUMP
TIME potentiometer on the side of the unit. Be
careful not to set the time too high with
samples that have limited headspace volume.
If your package appears to be totally
evacuated after sampling, or you hear the
pump “laboring” mid sample, re-set the pump
time to a smaller value. Avoid pulling the
entirety of the headspace of a package; this
can create a vacuum effect that will cause
erroneously low readings.
The pump draws about 5cc of volume per
second. The recommended pump time is 4
seconds, which would draw about 20cc of
volume from a package.
NEEDLE / FILTER REPLACEMENT
The needle and filter should be replaced if they
get plugged up and impede the flow. Both have
standard luer fittings, as does the probe tip,
and are simply pressed on with a twist to
provide a leak-free fit. A simple test can
determine if either is plugged:
1) Check to make sure the sample probe is
screwed into the instrument tightly at the
hex fitting.
2) Put the last needle and filter you used
on the end of the probe.
3) Press the pump button (without testing a
package) and watch the LCD closely.
4) The reading will go down, but what is
the minimum that it reaches?
a. if the reading goes down to 19-
20%, then goes back up to
20.9%, then you probably have
no blockage in the filter, needle,
or probe.
b. if the reading goes down to 14-
19%, then back up slowly to
20.9%, you have a blockage in
the filter, needle, or probe.
c. if the reading goes down to 10-
14%, then you have a very
serious blockage in the needle,
filter, or probe.
5) If you discover a blockage, you can
replace the needle first, and repeat the
test –or you can replace the filter and
repeat the test. If you replace the
needle and filter, you may want to check
the probe for kinks. 99% of the time,
you have a blockage in the needle
and/or filter.
SAMPLE PROBE ASSEMBLY
The probe assembly is a one piece assembly
and cannot be taken apart. The tubing used is
a very narrow bore inert polymer which
extends from the flanged end to the tip of the
probe assembly. The inert composition
prevents O2adsorption on the internal surface.
The internal tubing volume is small to minimize
the volume of sample required to flush out the
sensor to provide an adequate response time.
The tip is a male luer fitting which will accept
any luer-hubbed needle or filter. When
screwed into the bulkhead fitting, the captive
black screw presses the flanged end tightly
against a mating piece, also flanged, which
connects to the inlet port of the O2sensor.
The probe assembly should be replaced if any
part of it is cracked, or if contamination is
visible inside the tubing. Minor kinks in the
tubing are generally not a problem, but severe
kinks can impede the sample flow or can
develop a crack causing leaks. To replace,
unscrew the black plastic screw from the fitting
on the analyzer case. Inspect the interior of the
fitting for any dirt or particles, which might
cause a bad seal. Screw in the plastic screw
for the new probe. The threads are easily
stripped, so make sure that the screw is
properly aligned before tightening. Turn until
finger tight only. Do not use a tool to tighten,
because this can strip the threads.
BATTERY OPERATION AND RE-CHARGING
It is best to operate the instrument from the
batteries, and not leave it plugged in.
The unit will run 8-12 hours before needing
recharging. To re-charge the batteries, plug the
external charger module into a standard AC
outlet, connect the plug from the charger to the
jack located on the side of the 901, and turn
the unit off. A full charge requires 2-4 hours of
charging time. The unit will also operate with
four alkaline batteries, which are non-
rechargeable. However, these frequently leak
and can corrode the terminals with long-term
use. The unit is designed to operate with the
batteries supplied.
If the analyzer batteries are completely dead,
allow it to charge for at least 30 minutes before
attempting to use. If you must use the
analyzer right away, use alkalines –but don’t
charge the analyzer with alkalines installed!
BATTERY REPLACEMENT & CHARGER
Remove the battery cover by pressing and
sliding in the direction of the arrow. The
battery clips are designed to hold the batteries
fast, and a blunt tool is required to remove the
first battery. The batteries used are 4 X AA Ni-
MH rechargeables, 1.2 V 2600 mAh. Observe
polarity markings when installing new
batteries.
These batteries are designed to be slow
charged over a period of 4 hours, with the
charger provided. Do not use a charger other
than the supplied charger –it is a trickle
charger specifically designed to charge the
Model 901. Also, the jack and plug are of a
specific type and size.
NiMH batteries designed to accept a quicker
charge can also be used, as long as they are
AA size, 1.2-1.4 volt, and are of the NiMH or
Ni-Cad type. Do not use other rechargeable
types such as lithium. AA alkaline (non-
rechargeable) batteries can be used in some
situations, but extreme caution must be
exercised because plugging the unit into the
charger with alkaline batteries installed can
cause overheating or even melting of the
battery compartment.
The electronics and battery compartment are
fuse protected. This fuse is a thermal polyfuse,
which heats up and causes the main power
circuit to open when excessive current is
present. The fuse is located under the circuit
board and is not user accessible. If the unit
operates with the charger plugged in but not on
battery power alone, this fuse is probably
tripped. The fuse will reset itself after a period
of about 5 minutes if the source of the problem
is corrected. The fuse may trip if alkaline
batteries are used with the charger plugged in,
if the batteries are inserted incorrectly, or if a
short circuit is present in the wiring.
PRECAUTIONS
To avoid possible damage to the sensor, avoid
sucking dirt or liquids into the analyzer. We
advise that all sampling be done with the filters
provided which fits onto the end of the
sampling probe. Avoid direct sampling of
pressurized gas cylinders. High pressure can
cause damage to the sensor. To test the
content of a cylinder, flush the sample into a
plastic bag and sample from the bag.
ADVANCED SAMPLING CONCEPTS
Headspace volume: The amount of
headspace in your package can impact your
test results. There are two components to
this concept –package flexibility, and
headspace volume.
In general, it is best to avoid situations where a
vacuum condition is created when testing a
package. The oxygen sensor cannot discern
between a change in pressure, and a change
in oxygen. If you remove volume from a
package you are testing, and that package
does not collapse, you will reduce the internal
air pressure in that package. Not only will this
affect your readings (they will skew to the low
side), but the pump and sensor will age
quicker.
For reference, a K-Cup will contain about 7cc
of headspace. There are 355cc in a 12 ounce
soda can.
There are at least four different types of
packages / containers which we can profile:
1) High volume / Highly Flexible packages
(such as a bag of potato chips) - for
flexible packages, as long as the
amount of headspace is >20cc, then this
is generally not a problem. Imagine a
large bag of potato chips - the package
will collapse as sample is removed.
This is ideal, and your results will be
accurate.
2) Low volume / Semi-flexible packages
(such as a small, single serving snack
package) –for these packages, set the
pump time to be very short (3 seconds).
If the package appears completely
evacuated, then try not using the pump
–simply pierce the foam septa, and
squeeze the package. Alternatively,
you can remove sample using a locking
syringe, and inject it into the instrument.
3) High volume / Rigid Containers (such as
a 2L glass bottle) –if the bottle is empty,
you have 2000cc of headspace.
Removing 20cc of sample volume will
have very little effect on your readings,
as the air pressure will reduce by only
1%. You can test using the pump as
normal.
4) Low Volume / Rigid Containers (such as
a 10cc vial) –this will not be possible to
sample using the pump. There are
several workarounds –you can inject
water into the vial, while the needle has
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