A Liquid Filler for
Small and Medium Sized Operations
Inline Filling Systems designs and manufactures world class Filling Machine Equipment, Capping Machines, Labeling Machines, Turntables, Conveyors and other equipment for fully integrated liquid packaging lines.
This analysis deals primarily with
a lower capacity liquid filler used by small to medium sized companies
and excludes high speed rotary liquid fillers typically found only in
the mass market beverage industry. In contrast, the liquid fillers discussed here
are used throughout all industries including food, beverage, chemical,
cosmetic and pharmaceutical but at lower speeds; usually less than 200 containers per minute.
In fact, most of the market for a liquid filler in terms of units sold is for semi automatic
equipment that operates at speeds not exceeding 20 containers per
No one type of filling machine can handle all liquids in all industries.
For example, a machine that fills bottled water cannot fill cosmetic
cold cream. Nor would a chemical duty filler be used to fill
pharmaceutical grade or dairy products. Although
there are many different types of filling technologies, there are
relatively few that are versatile, practical and cost
effective to own and operate. The choice of filling machine depends on
the range of viscosities, temperature, chemical compatibility,
particulate size, foam characteristics, and hazardous environment
considerations. Each one of the machines below is discussed with its
strengths and weaknesses and range of best suited applications.
Overflow liquid filler
This type of filler is perhaps the most widely used
machine in small bottle filling operations because it handles a
wide range of thin, free flowing liquids as well as liquids with
medium viscosity. This machine is also commonly referred to as a
"fill to level" filling machine or cosmetic height filler. This
means that machine fills to a target fill height in the
container rather than volumetrically. But it can also be shown
that as long as the container specification do not vary greatly,
the volumetric accuracy of this machine is excellent.
Because this filler operates in a closed loop basis, it is also
ideal for handling foamy products. The Examples of
products that work well in this filler are bottled water, liquid
soap, motor oil, cleansers and even some dairy products. It can
be constructed in both chemical duty versions as well as
sanitary versions capable of filling pasteurized products at
This machine is relatively low cost and easy to use. However it
is generally not useable for products with viscosities greater
than 25000 centipose or products that have any particulates
exceeding approximately 1/16" diameter.
Click here for a guide to selecting Overflow Filling Machines.
Servo Pump liquid filler
This is a very versatile filling machine capable of
filling nearly any type of product that can be pumped. Each
nozzle has a dedicated servo controlled pump that can deliver
thin liquids, medium and thick viscosity liquids, and liquids
with large particulates. Because it is so
versatile, it is often purchased by contract packagers who never
know what their next filling challenge is going to be. Examples
of the range of products that can be run on this machine include
soaps, pharmaceutical products, oils and greases, cosmetics,
salsa and sauces, etc. etc.
The challenges of this machine are its high capital cost and the
ability of the owner to conduct normal maintenance on a more
sophisticated machine. Positive displacement pumps are expensive and so are servo
controlled drive systems. Troubleshooting and maintenance
requires reasonably competent technical level. However, if
affordable, this type of filler is an outstanding choice for
nearly any type of filling operation.
Click here for a guide to selecting Servo Pump Filling Machines.
Peristaltic liquid filler
This filler is the
machine of choice for high value, small volume fills at very
high accuracy. It is primarily suitable for aqueous and other
light viscosity products. Examples of products filled on this
machine are sterile and pharmaceutical preparations, fragrances,
essential oils, reagents, inks, dyes, and specialty chemicals.
The unique advantage of this machine is that the only fluid path
is surgical tubing. The fluid path is disposable; easy to
cleanup and eliminates cross contamination problems. Accuracies
of 0.5% are achievable for fill volumes less than 1 ml.
The peristaltic pumps on this filling machine make intermittent
contact on only the outside of the surgical (product) tubing so
that the product only touches the inside of the tubing. Like the
servo pump filling machine above, this system operates with
servo drives. Each servo drive is dedicated to one or two
peristaltic pump heads. The filler's master computer
independently tracks the # of rotations of the peristaltic pump
head so that it knows precisely how much product has been
delivered. When the target fill volume is reached, the pump
stops and the remaining product fluid does not drip out due to
pipette action of the surgical tubing.
Click here for a guide to selecting Peristaltic Filling Machines.
Gravity liquid filler
This is the most economical type of filling machine
for a limited range of applications. This filler is best suited
for liquids with very thin viscosities that do not change with
ambient temperature or with batch variation. This machine is
also suited for applications where recirculation of the liquid
in the fluid path is not desirable. This is especially true for
corrosive chemical filling like acids and bleach. Other examples
of products this machine is well suited to include water,
solvents, alcohol, specialty chemicals, paint and inks. Although
this type of filler is used predominantly on products that do
not foam, foam may be limited and controlled by
The machine works by a simple principle; the amount of liquid
flowing through a fluid path will always be the same for a fixed
amount of time. It functions as follows: the product bulk supply
is pumped into a holding tank above a set of pneumatically
operated valves. Each valve is independently timed by the
filler's master computer so that precise amounts of liquid will
flow by gravity into the container. Independent timing of each
filling valve/nozzle corrects for minor variations in flow rates
so that each container is filled accurately.
The disadvantage of this type of technology is that the dynamics
of the fluid path and nozzle actuation characteristics
continuously change over time. This requires the operator to
make adjustments to the machine's stored parameters more
frequently than other technologies. Notwithstanding this
drawback and the limitation of the range of products that can
run on this filler, it offers excellent value for its
Click here for a guide to selecting Time Gravity Filling Machines.
The piston filler is one of the oldest and most
reliable types of fillers used in the packaging industry. This
filling machine is best suited for viscous products that are
paste, semi paste, or chunky with large particulates. Piston
fillers are primarily built to meet food grade standards and
commonly fill heavy sauces, salsas, salad dressings, cosmetic
creams, heavy shampoo, gels, and conditioners. Thy are also used
for viscous chemical preparations like paste cleaners and waxes,
adhesives and epoxys, heavy lubricant oils and greases.
The machine works by a simple principle; The piston is drawn
back in its cylinder so that the product is sucked into the
cylinder. A rotary valve then changes position so that the
product is then pushed out of the nozzle instead of back into
the hopper. The volume of the product that is sucked into the
cylinder is the precise volume that will be dispensed into the
The advantage of this type of filing machine is that involves
conventional mechanical technology that is easy to understand
for most users. It is also the most cost effective, accurate and
fastest way to fill fairly thick products. Although more costly
than overflow and time gravity systems discussed above, it costs
less than the servo pump filler is still the most cost effective
filling machine for thick products.
There are several disadvantages this type of filler. It is
practically speaking, NOT suitable for thin products because the
mechanical characteristics and clearances of the machine parts
allow for leaks on thin products that do not occur on thicker
products. The other major disadvantage of this machine is that
if there are multiple product and container size changes
involved, the cleanup and "tweaking" processes are tedious and
time consuming. Lastly, there is a finite range of fill volumes
per piston set that can be run on the machine. An operator who
needs to fill both gallon containers as well as 8 oz containers
will find they cannot run the 8 oz containers accurately using
gallon or half gallon piston sets. (This is where the servo pump
filler is superior)
Click here for a guide to selecting Piston Filling Machines.
Weigh liquid filler
This type of filler is best suited for liquids filled
in bulk quantities e.g. 5 gallon pails, etc. or smaller quantity
products that have a very high manufactured value. Oftentimes
there are products that must be sold by weight for commercial
reasons and therefore this filling machine is the only choice.
Examples of this type of filler for bulk products include
cleaning chemicals, enzyme solutions, oils and other medium
value products. High value products filled by these machines
include specialty adhesives and paints, precious metals
dissolved in acids, and other expensive specialty chemicals.
The operation of this type of filling machine is simple. The
product bulk supply is pumped into a holding tank above a
pneumatically operated valve. The valve opens and real time net
weight information is monitored until the target weight is
achieved. The valve simply shuts when the target weight is
achieved. Accuracy of fills is accomplished by various "bulk and
dribble" methods in the filling process so that overfills are
The advantage of this filling machine over others is that it is
sometimes the only practical (and legal) type of filling for a
limited range of applications and for large volume fills. It is
also very accurate and effectively provides its own quality
control assuming the scale is functioning properly. The
disadvantage of this type of filling machine is that it is very
expensive per filling head and it is also a relatively slow
method of filling into a container. For these reasons, the use
of this filling technology is limited to the examples outlined
Click here for a guide to selecting Net Weigh Filling Machines.
Any of the machines outlined above can be built for
Hazardous Location operation. Hazardous location means that
there is risk of explosion or auto-ignition of the products
being filled. Examples of products like this are alcohol,
solvents, petroleum products, paints, etc.
Many of the manual and semi automatic versions of the types of
a liquid filler discussed above are inherently safe since they
require no electrical operating systems. However, more
sophisticated and higher output automatic machines using
electrical systems must be built with intrinsically safe
enclosures that are UL listed and conform to the National
Electric Code as well as requirements of major insurance
There are automatic a liquid filler offered in the market with
completely pneumatically controlled operating systems. However,
the major disadvantage of these systems include susceptibility
to inconsistencies of plant air volume and pressure. In other
words, there is risk that pneumatic logic controlled machines
will not function repeatably. For this reason, hazardous
location a liquid filler using electrically safe systems are
prefereable because they can offer all the consistency,
convenience, and efficiency of conventional fillers including
full visual displays and user friendly controls.
The disadvantage of this type of system is high capital cost but
oftentimes, there is no choice in the matter.
Click here for a guide to selecting Hazardous Location Filling Machines.
Corrosive Environment liquid filler
As suggested above, time gravity fillers are often
used for filling of corrosive products. But sometimes the
products being filled are so aggressive that special
construction methods are required. Harsh factory environments or
where the product being filled can also be particularly
aggressive on machinery. This includes not only chemical plants
plants producing strong acids or bleach but also food plants
using brine or sugar solutions in their products. In both cases,
even the factory air alone contributes to the accelerated
degradation of the machinery.
Machine integrity can be enhanced by using special powder and
industrial polymer coatings on structural and other exposed
machinery components. Also, whenever practical, substitution of
chemical resistant plastics such as UHMW and Teflon are used in
place of metal.
Not only are the frame components at risk in these environments
but the fluid path materials must be specifically chosen for the
types of products they come into direct contact with. For
example, Kynar and Teflon fluid path materials may be used in a
bleach filling machine because of their excellent resistance to
the aggressive properties of bleach.
It should be noted that there is no ideal combination of
materials in a filling machine when it comes to corrosive
filling. Avoidance of some metal components is impossible
particularly in the case of fasteners. The operator of this type
of machinery should be prepared for stringent maintenance of
these types of machines.
Click here for a guide to selecting Corrosion Resistant Filliing Machines