Because of foam our eyes are not capable to establish a defined level for the beverage in the glass, in this 3-dimensional animation. Nor it is easier for the most advanced fill level measurement technologies
X-ray fill level inspection with one bridge
The 3-dimensional animation above shows a fact: because of foam our eyes are not capable to establish a defined level for the beverage in the glass. And, what about the Bottling Control fill level measurement technologies? We yet saw the X-rays technology may also be successfully used in terms of:
- Qualitative performances;
- smallest possible false rejects;
as fill level inspection system, on:
- common soft drinks, out of the Filler;
- common soft drinks and water, out of the Labeller Machine;
- beers, after the Pasteurizer;
- waters, carbonated or not, after the Filler or Labeller Machine;
A benchmark of different fill level technologies. X-rays, Infrared (IR) and High Frequency (HF) in the electromagnetic spectrum, based on the energies involved by mean of the E = hv fundamental formula (where v = c/λ, c speed of propagation of em waves in the vacuum, λ wave length, v frequency, h Planck's constant, E energy of the photon). In the case of the Bottling Controls the energy of a single X-ray photon results ~ 100 000 000 000 times greater than that associated to an High Frequency (HF) at 21 MHz. Consequently, as seen by a X-ray the foam in the bottles’ neck is detected nearly as vacuum, say no absorption, preventing the measurement of the liquid in this form (image adapted under Creative Commons 3.0)
But, it’s a fact it requires special cares when applied after the Filler on beverages foaming like the beer. The amount of beverage foaming measured on the fill level inspection bridge is a subject deepened elsewhere in this website, where it is examined the High Frequency fill level inspection.
The amount of foam mixed to the beverage liquid phase in the container (PET or glass bottle) measured by a fill level inspection, is associated to the simultaneous presence of one or more distinct factors, mainly:
- sugar diluted in beverage;
- temperature of the beverage;
- time interval along the transfer from the Valves' closing cam of the Filler Machine til the fill level inspection bridge;
- format and shape of the container.
The X-rays fill level inspection requires special cares when applied after the Filler to beverages as foaming as beer
A Matter of Time
The Bottler has:
- no influence on the first factor: the amount of sugar diluted in the beverage;
- influence on the second factor: the beverage temperature and, regarding this point consider what suggested here.
- limited influence on the fourth factor: containers' format and shape;
- a moderate influence over the possibility to provide a Bottling Hall and Line Layout extended (expensive) as much as necessary to let the bottled beverage reduce the foam in favour of liquid.
What above, introduced a fact: if the Layout of the Conveyors in the area between Filler-Closer out feed and the Full Bottle Inspector, conditioned by the nominal speed of the particular format considered, allows adequate time it'll be always possible to apply the X-ray fill level inspection also to beers. In the following we’ll consider, by mean of practical examples, three different cases:
If the Layout of the Conveyors in the area between Filler-Closer out feed and the Full Bottle Inspector, conditioned by the nominal speed of the particular format considered, allows adequate time it'll be always possible to apply the X-ray fill level inspection also to beers
Example 1
Fill level inspection of beer out of the Filler Machine
at 60000 bph, 1.88m/s
Refer to a Bottling Line whose Filler Machine is an high speed model:
- rated 60000 bottles-per-hour;
- machine pitch 113 mm;
- containers' speed 1.883 m/s;
- filling beer;
- equipped with foamer spray jets (a thin jet of hot water sprayed into bottles necks to force foaming, so to release out of the bottle the otherwise dagnine Oxygen);
- double fill level inspection in the Bottling Line, the first set at low sensitivity after the Filler Machine and the second set at high sensitivity, after the Labeller Machine;
if there are at least 3 meters from the Closer out feed star wheel transfer point til the fill level inspection bridge, it'll be possible to use with full success X-rays, whatever the shape and format of the bottles. 3 meters only because we are considering a Bottling Line equipped with two fill level bridges rather than one:
- the first, after the Filler Machine, a mere service inspection of the Filler, devoted to eliminate huge under fillings and non-closed bottles, plus advanced sampling and locating functions;
- the second, after the Labeller Machine, the Electronic Inspector which really does the Quality out feeding by the Bottling Line, whose X-ray fill level inspection operate in the best conditions of Signal/Noise ratio (S/N) detecting minimal under or over fillings.
Example 2
X-ray fill level inspection of beer out of the Filler Machine
at 60000 bph, 1.88m/s
To give an idea, refer to a Bottling Line whose Filler Machine is a high speed model:
- rated 60000 bottles-per-hour;
- machine pitch 113 mm;
- containers' speed 1.883 m/s;
- filling beer;
- equipped with foamer spray jets (a thin jet of hot water sprayed into bottles necks to force foaming, so to release out of the bottle the otherwise dagnine Oxygen);
- unique fill level inspection in the Bottling Line, after the Filler Machine;
if there are at least 12 meters from the Closer out feed star wheel transfer point til the fill level inspection bridge, it'll be possible to use with full success X-rays, whatever the shape and format of the bottles. And, if all of the nominal data above listed are maintained and the product filled is not beer, rather e.g. Sprite®-like high-sugar highly carbonated soft-driks, that distance can be reduced to 6 meters.
Example 3
X-ray fill level inspection of beer out of the Filler Machine
at 30000 bph, 0.942 m/s
Refer to a Bottling Line whose Filler Machine is an high speed model:
- rated 30000 bottles-per-hour;
- machine pitch 113 mm;
- containers' speed 0.942 m/s;
- filling beer;
- equipped with foamer spray jets (a thin jet of hot water sprayed into bottles necks to force foaming, so to release out of the bottle the otherwise dagnine Oxygen);
- unique fill level inspection in the Bottling Line, after the Filler Machine;
if there are at least 9 meters from the Closer out feed star wheel transfer point til the fill level inspection bridge, it'll be possible to use with full success X-rays, whatever the shape and format of the bottles. There are precise reasons why this last case of Filler Machine, running one-half of the speed of the one considered in the Example 2, does not allow to cut to one-half also that distance. The dimension of the foam bubbles, their amount per cubic millimetre, and other factors not directly visible with our eyes concurs to define a minimum time for foam relaxation, so that foam still exist but no more preventing a precise X-ray inspection.
The level of a foamy beverage cannot be univoquely defined (image credit GROLSCH®, a SABMiller company)
Quality means 2.
The performances of the Fill level inspection, whatever its Technology, out of the Filler Machine are always intertwined with the Layout. A qualitative detail in a place results caused by the qualitative-productive greater environment. Kept apart still products or slow speed Bottling Lines (< 0.5 m/s), a minimum distance of 1 m each 10000 containers-per-hour has always to be respected. Alternatively, they have to exist two distinct fill level inspectors, strategically placed in different points of the Food and Beverage Bottling Line. Then, containers shall be examined for their filling level a first time by an Inspection set at extremely low sensitivity, low but adequate to reject containers where the underfilling is > 10 mm. A second time, by an Inspection at high sensitivity, meaning the measurement device limit, for X-ray technologies typically close to an underfilling of 1.0 mm guaranteed rejected on 99.99 % of times with a false rejects (false positives) ratio < 0.01 %. Approximately ten times worse performances for High Frequency (HF) fill level technologies.
Links to other pages about Fill Level Inspection:
