Small company benefits from HVLP spray guns

Citation

(1999), "Small company benefits from HVLP spray guns", Pigment & Resin Technology, Vol. 28 No. 3. https://doi.org/10.1108/prt.1999.12928caf.001

Small company benefits from HVLP spray guns

Small company benefits from HVLP spray guns

Keywords Environmental impact, Paints, Spray deposition

This case study demonstrates that small, as well as large, companies can save money by changing to high volume low pressure (HVLP) spray guns.

Used properly, HVLP spray guns increase transfer efficiency, reduce paint consumption and produce a high-quality finish. Volatile organic compound (VOC) emissions are reduced as a result of the reduction in paint consumption.

DB Partners Ltd ­ a small company with 43 employees ­ bought 15 HVLP spray guns and fully enclosed spray gun cleaning equipment to reduce its use of solvents and so meet the requirements of registration under Local Air Pollution Control. The change was accompanied by specialist training for all operators so that the benefits of using the new spray guns could be fully realised.

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  The benefits of the project include:

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  an initial reduction in paint use of 21 per cent;

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  a payback period of three months;

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  continuing paint savings worth £40,500/year;

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  reduced environmental impact.

Background

Over recent years, increasing numbers of companies that use paint spraying equipment have switched to high volume low pressure (HVLP) spray guns to reduce solvent use and meet the requirements of the Environmental Protection Act (EPA) 1990. These companies have also made substantial cost savings from reduced paint consumption because HVLP spray guns are potentially more efficient than conventional designs.

In general, smaller companies have not followed this trend. This has been mainly because their solvent use falls below the 5 tonnes/year threshold for registration under Local Air Pollution Control (LAPC), so they have not been required to change to HVLP spray guns. In addition, it has been unclear whether any cost savings would be sufficient to make the change worthwhile.

This case study focuses on the experience of DB Partners Ltd ­ a small company that registered under LAPC as part of a commitment to becoming "best in class". Although its solvent use fell below the threshold for compulsory registration, the company believed that registration would enhance its standing in the marketplace and lead to increased orders.

To improve the efficiency of its operations, the company bought 15 HVLP spray guns and installed a fully-enclosed spray gun cleaning station. Since buying the spray guns in Autumn 1995, DB Partners has made significant cost savings, showing the benefits which can be achieved by any small company switching to HVLP guns.

HVLP spray guns

Compared with conventional spray guns, HVLP guns atomise paint using a higher volume of air at a lower pressure. Paint spray is therefore less likely to bounce off workpieces, and overspraying is reduced considerably. HVLP spray guns increase transfer efficiency, and ensure that more paint gets onto the pieces being sprayed (Figure 1).

Experience in many applications has shown that modern HVLP spray guns, when used properly, are as effective as conventional guns and will produce as good a finish.

Figure 1 Using an HVLP spray gun

Remember ­ spraying with HVLP spray guns is different from conventional spraying

To get the most out of HVLP spray guns operators need to change the way in which they spray. Most importantly, they should:

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  spray a little closer (150-300 mm is a good distance);

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  keep the spray at right angles to the workplace ­ do not bend the wrist;

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  reduce the paint flow, or spray a little faster, to save material.

Training

When DB Partners bought the new spray guns, all its operators received three days' training in the modified spraying technique required to produce a high-quality finish. A consultant provided theoretical and practical training, which covered all aspects of finishing, including paint and spray gun technology, and a practical demonstration of how to set up and use the spray gun. The training also provided hands-on experience, highlighted how to get the best out of the new system, gave general hints on spraying, and emphasised the need for care to prevent low-quality finishes and waste.

Although it was an extra expense, DB Partners saw this training as an essential part of the project. It realised that misuse of the new equipment would result in low quality finishes. In fact, the training was so successful that operators are now reluctant to use traditional spray guns. The quality of finish achieved with the new equipment is at least as good as it was with the old.

Financial benefits

Measurement of paint and solvent use in the six months following installation of the new spray guns has shown that there was a 21.2 per cent reduction in paint use (2,393kg of solvent used instead of the 3,037kg that would have been required for the conventional spray gun). This reduction is equivalent to 894 litres of paint and represents a cost saving of £11,175 at an average price of paint of £12.50/litre. The 15 spray guns cost £300 each, and the three days of training cost £400/day. HVLP guns use less compressed air than conventional guns, so there is a potential energy saving which will reduce running costs. Maintenance costs remained unchanged.

Table I shows the annual savings calculated from paint and solvent use during the first six months, capital and training costs, and the payback period.

Table I Economic analysis

Cost savings

Annual savings in paint consumption £22,350

Costs Purchase of 15 HVLP spray guns £4,500

Training £1,200 Total costs £5,700

Payback period 3 months

DB Partners continues to make savings, now at an even higher level because of increased business (Figure 2). The Company currently uses 8,764kg of solvent/year compared with an estimated 11,098kg/year it would have used if it still had conventional spray guns. This represents a reduction in paint consumption of 3,240 litres/year, which is worth £40,500/year. The reduction in solvent consumption means that the Company has also reduced VOC emissions significantly.

Results of experimental comparison

The efficiency of an HVLP spray gun was tested against that of a conventional spray gun by having an operator coat identical components on identical jigs using the same paint. The tests were run consecutively and the dry film thickness was measured after spraying. The surface was inspected visually to confirm the acceptability of the finish. The dry film thickness of the HVLP coating was found to be slightly thicker.

The spray guns were weighed before and after spraying to measure paint use. The average paint use per jig with the conventional spray gun was 212.5g compared with 135.7 g for the HVLP spray gun. This represents a 36.1 per cent reduction in the paint used.

These calculations are based on the amount of paint sprayed from the paint cup. In normal use, efficiency improvements might be lower because of factors such as residues in the spray gun after spraying and waste from filtering or stirring the paint.

Figure 2 Can you benefit from using HVLP spray guns?

Further information

The Good Practice Guides listed below provide further information on the efficient use of solvents and are available free through the Environmental Helpline on freephone 0800 585794.

Good Practice Guide (GG50) Cost-effective Paint and Powder Coating: Materials Management.

Good Practice Guide (GG51) Cost-effective Paint and Powder Coating: Surface Preparation.

Good Practice Guide (GG52) Cost-effective Paint and Powder Coating: Coating Materials.

Good Practice Guide (GG53) Cost-effective Paint and Powder Coating: Application Technology.

For further information please contact the environmental helpline on +44 (0) 0800 585794; E-mail: etbppenvhelp@aeat.co.uk; http://www.etsu.com/etbpp/