Lower running costs
July 26th 2007

Throughout manufacturing industry, compressed air is used for a wide range of tasks. “However, it can be costly and inefficient, particularly if used for the wrong application.” says Adam Battrick, international product manager for the JetStream air knife system from Meech International

As well as the high cost of generating compressed air, its inefficient use for ‘blow-off’ applications, in particular, has a negative effect on the company’s carbon footprint, thereby increasing the energy tax bill. Companies need to look at more efficient, costeffective and eco-friendly ways to clean and dry their products.” Adam further explains. “There have been significant improvements since the bad old days of open pipe compressed air systems but in many applications even using fishtail/windjet nozzles or air curtains can be highly inefficient”.

With the Meech JetStream blower driven system, energy savings of 70-90% are commonplace due to the fact that JetStream requires only a fraction of the electrical energy input compared to compressed air equipment.

Running costs

The example shows the financial benefits of using a JetStream blower driven system compared to either compressed air fishtail nozzles or air curtains. All the calculations are based on an electricity cost of £0.05/kWhr and compressed air kW requirement based on 4CFM = 0.75kW. The running time is 16 hours per day, 5 days per week, 48 weeks per year.

In a real life situation, 20 fishtail nozzles, each 47mm wide and spaced at 28mm, will cover a length of approximately 1500mm. Each nozzle consumes 16CFM of compressed air when running at 80 psi inlet pressure. This gives a total consumption of 320CFM, requiring 60kW of electricity and a cost of almost £12,000 per annum. A single 1500mm length of air curtain, however, consumes 4.3CFM of compressed air per 25mm, when running at 80psi inlet pressure, giving a total consumption of 258CFM. This requires 48kW of electricity to generate, at a cost of £9,000 per year. Alternatively, a single 1500mm JetStream requires only an 11kW blower to run, reducing the annual running costs to only £2,000 a year.

Not only are JetStream systems energy efficient but they also provide additional benefits when compared to compressed air products. They are available in either ‘ionising’ or ‘nonionising’ formats to suit different applications. For example, an ionising system is suitable for removal of dust/fibre contamination from a surface whereas a non-ionising system is suitable for all drying applications.

The basis of operation of the JetStream system is that highpressure air is generated at the blower unit and delivered to the air knives through ducting. The air is then discharged from the air knives at a velocity of approximately 100 metres per second. With ionising JetStream systems, air leaving the air knife passes between two integral ionising bars. This ionised air, aimed at the components to be cleaned, will break electrostatic bonds holding contaminants to the surface, thereby enabling effective removal and preventing re-attraction. The energy efficiency of JetStream can be further improved by incorporating an inverter into the system to allow accurate performance set-up for each run of products to be cleaned/dried.

The ‘tear drop’ designed JetStream air knife also delivers a balanced, continuous blade of ionised air for consistent performance. This is unlike fishtail nozzles which will always have a space or ‘dead-spot’ between them. The constant airflow pressure and volume delivered by JetStream is also a considerable advantage, as often in busy factories, the airflow from a compressed air product can fluctuate. This is a particularly common problem if, for example, several blowguns are used at the same time so reducing the air available for the nozzles or air curtain. In addition, JetStream systems do not suffer the potential quality problems associated with compressed air condensate and oil.

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