CHART CryoDoser FleX, Product Manual

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16 Daily Operating Procedures Product Manual - CryoDoser FleX
™
LN
2
Dosing System
1 Sensors provided for Chart dosing systems are as
follows:
Timing
Container detect
Encoder
• Timing - typically an inductive proximity device.
This sensor will provide a pulse identifying a start
time where a container has been detected until it
reaches the dosing head. This sensor is suitable
for detecting on any metal object such as a gear
tooth or shaft collar bolt. This sensor is typically a
barrel type and comes in three different diameters:
13mm, 18mm and 30mm. Sensing distances are
approximately as follows:
13mm dia. = 2mm (0.08 in.)
18mm dia. = 4mm (0.2 in.)
30mm dia. = 7-8mm (0.3 in.)
• Container detect - Typically a photo-electric device.
This sensor will provide a signal identifying an
approaching container. It is capable of detecting
virtually any type of object that is placed within its
sensing distance, therefore good for cans, bottles,
pouches of all shapes, sizes and colors. The sensing
distance may vary based upon the manufacturer
of the sensor but it typically has a range of
approximately 4 inches (10cm).
The sensor is typically a barrel type and is provided
in an 18mm diameter
The sensor is typically placed at or near the dosing
head. It also serves the purpose of nozzle cooling
when placed at some short distance in front of the
dosing head. This feature can be very important
when the filler tends to sit idle with no containers
passing for short periods of time.
As the system sits without dosing, the dosing head
heats up which results in the next dose (or couple
of doses) being slightly warmer and therefore more
gaseous. This will result in lower pressure in the first
few containers
• Encoder - this device does provide an input to the
control box but unlike the other two sensing devices
that provide one pulse each time it is triggered,
this device provides hundreds or even thousands of
pulses. The device can be programmed to output up
to the maximum capability of the device (65,000
pulses per shaft revolution). Considering the standard
pulses necessary for high speed dosing is about 500
pulses per container, this encoder is capable of many
more than needed to perform optimally.
How much LN
2
is needed?
Identifying the right amount of liquid can be challenging.
Some trial and error is commonplace. However, there are
a couple of ways to minimize the number of trial and error
situations
1 Use the largest nozzle and lower the dose duration. It
is much easier to punch a button rather than removing
a nozzle so the fewer number of times a nozzle is to be
removed, the better. Start with a larger nozzle size than
you think is necessary and run a shorter dose duration
than what is probably needed. Test to see what the
pressure or oxygen level is and increase the duration
until a desirable result is achieved.
2 Use a continuous stream as a starting point. Targeting
a small opening can also be challenging. However,
if a continuous stream is used initially it can then be
reasoned that the nozzle size is correct. The second
half of this test is to then “shorten” the stream. In other
words target the stream to start and stop within the
opening.
3 Semi-continuous stream - a trick to use when
targeting is more difficult due to erratic conveyor
movement, environment issues, poor sensing or sensor
susceptibility is to start and stop the stream before and
after each container. Set the dose early (starting just
before the container gets under the dosing head) and
end it just after the container has passed.
4 How do you know if you’re hitting the target? Two
simple techniques:
• Look for the “smoke” out of the container
• Feel test
Is the smoke good enough? Depending on your
specification and/or requirement more or less nitrogen
may be needed. Once smoke is seen, a measurement is
taken (pressure or oxygen levels). That measurement can
then be used to determine whether more or less nitrogen
is needed. Increase the dose duration. If the pressure
goes up, the initial target was fairly accurate. If it stays
the same, then the initial target was a bit late and the
added dose duration just placed nitrogen into the space
after the container has passed. In this case move the
targeting sensor so it triggers sooner
What about oxygen content? This will require an oxygen
meter or tester Oxygen measurements can be even
trickier.