Counter-pressure filler

One popular misconception concerns the counter-pressure filler. It is often stated that the overpressure of gas in the filler bowl pushes the product into the container, but this is not the case. Once the valve is open the pressures in the bottle and the filler bowl equilibrate and product is filled by gravity. (Note a counter-pressure filler is usually used for carbonated beverages but it can successfully fill still products with an inert overpressure.)... 

The choice of a filler depends on the number of bottle sizes being considered for use on it. For example, if 3 1 PET bottles are to be filled, a 126 mm pitch between filling valves is required. If only small bottles up to 500 ml are to be filled, then a 70 mm pitch will suffice. This has a direct effect on the size of the filler and its footprint on the factory floor. Unless the filler bowl level is kept within tightly controlled limits, pressure head variations will affect the rate of flow into containers. Systems such as that shown in Figure 7.15 need to be employed. Wherever possible there should be minimal contact between any instrumentation and the product. Conventional float valves should be avoided and simple capacitance probes, which are easily cleanable but small and very effective, should be used. It is not uncommon in older fillers to only have one float valve. This often gives rise to filler bowl flooding, which may lead to inconsistent fill level and poor counter-pressurisation of the container pre-filling. 

Flow Proportional Counter. The flow proportional counter covers a wide wavelength range and is generally used for wavelengths longer than 2 A (elements with Z < 27). This detector is illustrated in Fig. 8.24(a). The windows are thin (<6 pm) polymer film, coated on the inside surface with aluminum to permit a homogeneous electric field to be established within the detector. The thin windows allow the filler gas to leak out therefore a supply of filler gas is constantly provided to the detector through the inlet as shown in Fig. 8.24(a). The filler gas for a flow proportional counter is often 10% CH4, 90% Ar, a mixture called PIO gas. The pressure, flow, and temperature of the gas must be precisely controlled for accurate detector response. 

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