We all like a perfect finish. Whether you're spray painting a car, the inside wall of a house, or a garden fence, you want it to look perfect. However, despite thorough preparation, if the paint application is not spot on the end result can resemble the "orange peel" effect. Our handy air compressor set up for spray guns will guide you through all the things you need to know.
DIY and professional work can be carried out using the HVLP (high volume low pressure) spray guns. Therefore, it's important when trying to get a flawless finish, that the compressor can deliver both psi (pounds per square inch) and cfm (cubic feet per minute) required by the spray gun. Pressure drop and volume loss, two of the main causes of imperfect coverage, can be minimised with careful set up of the compressor and spray system.
How Narrow is the Air Hose?
The hose, can be the source of pressure drop if too narrow or too long. For example, a smaller inside diameter (ID) of the air hose translates to less air getting through the line. Consequently this causes less air pressure to be delivered to the spray gun. Using a 5/16 inch (7.9 mm) hose causes less pressure than using a wider diameter 3/8 (9.5 mm) hose.
It is advisable to use a hose with an ID of more than 1/4 inch for all spray guns. HVLP (High Volume Low Pressure) spray guns have larger volume requirements. To ensure maximum air is available to the spray gun, a hose larger than 5/16 inch ID will be needed. However, bigger is not always better as the length of the hose will also need to be taken into consideration.
Is the Air Hose too long?
As the compressed air travels through the hose, the pressure decreases with increased distance from the compressor. Therefore, it is best to use hose length and ID to reduce the restriction of the air supply.
8mm diameter, 10m long rubber air hose comes with quick release connectors.
10m polyurethane recoil type hose
fitted with a two female 1/4" BSP threads.
20 metres of durable braided PVC hose
and snap fit air inlet/outlet connections.
10mm diameter, 10m long PVC air hose comes with quick release connectors
6mm diameter, 15m long rubber air hose comes with quick release connectors.
Quick Disconnect Fittings (QD's)
Depending on how many are used and their design quality, the air connectors could be a potential source of loss of air pressure. Despite their the fact that they are convenient.
How Many QD's Are There?
Using a large number of air connectors can be expensive in terms of pressure drop. And are they really necessary? The simple answer is no.
The connectors may be unnecessary attachments, if the air hose is only removed from the gun only once or twice a day.
Are The QD's Too Restrictive?
Depending on the design and volume requirements, the pressure drop from a QD can vary between 1 and 25 psi. It's important to choose a QD design carefully. You want to ensure you pick the least restrictive unit. One feature that is indicative of a large pressure drop is a small aperture in the female portion of the QD. If it is small there will be a larger restriction on the air travelling to the spray gun. An opening of 0.196 inches would, for example, provide an area 2.4 times smaller than the area of an aperture of 0.305 inches. Using "high flow" QD's with the biggest diameter practical ensure minimal pressure loss.
Is the Air Regulator High Flow and of Good Quality?
Air regulators provide precise adjustment of the airflow air pressure for consistent results. However, their design can also restrict air flow and create excessive pressure drop. There are two types of regulator - wall-mounted and gun-mounted. Typically, larger wall-mounted regulators provide constant air pressure to the gun, minimising the pressure drop. As a result, the air regulator should be capable of flowing enough air for the spray gun and have capacity greater than the spray gun demand.
To determine if the regulator is too restrictive, compare readings on the gauge when in use and when it is not. The difference between the two readings should be 5 psi or less. Although air pressure is regulated, the system may still have fluctuations. This can happen when an air-adjustment valve-type restrictor is being used. The air will exit the air cap with an initial burst of pressure. Which then levels off to the adjusted pressure, but may vary because of changes in system pressure.
Air Filter, Water Trap, Regulator & Lubricator
Air Filter, Water Trap & Regulator
High Quality Air Lubricator
What is the Performance Specification of the Air Compressor?
The requirements of the compressor are that it needs to supply sufficient, clean, dry air. It needs to be of the correct size to facilitate the air pressure and volume requirements of the whole system. This is important because as previously mentioned, the restrictions of Qd's, narrow hose ID, and alternative air tools.
The compressor must also provide clean (oil free) and dry (water free) air. The air tank must be drained of any water and the filters checked to determine they are clean and functional. It is also advisable to have a final air filter installed at the gun itself. To read more about the various specifications of air filters, check out our air compressor buying guide here.
Spray Gun Kits
If you're new to spraying we recommend starting with our ready made 6 Litre Oil-Less Air Compressor & Spray Gun Kit. The air compressor kit comes complete with a professional spray gun, air regulator, 10m hose, spray gun cleaning kit euro quick release couplers. Ideal for anyone looking for a lightweight piece of equipment for occasional small at home DIY projects.
Secondly the plucky SGS 24 litre, 9.6 CFM compressor is fully equipped with a HVLP gravity fed professional spray gun, 10m rubber air hose, regulator with gauge, mini air filter and water trap and 2 quick couplers. This kit is ideal for anyone recently starting out spray painting. The kit is an incredible combination of performance, safety and value.
This 50 litre high flow reciprocating air compressor has the capacity and delivery to ensure you always get fantastic results. The kit boasts a large 50L tank that really makes this kit a top contender for serious enthusiasts and semi-professional sprayers. This kit is fully equipped with a HVLP gravity fed professional spray gun, 10m 6mm rubber hose with quick couplers, mini air filter and 1 litre of compressor oil. Our compressor spray gun guide has all the info you need to get up and running.
Finally our 100 litre high flow air compressor and spray gun kit can provide you with everything you need to quickly and efficiently complete any spray painting work you may have. The 100L air compressor kit comes complete with HVLP gravity fed spray gun, 2x 6m rubber hose with quick couplers, air filter, water trap, regulator & lubricator, euro quick couplers, mini air filter and 1 litre of AC 2068 compressor oil. Therefore, making this kit ideal for regular or even semi-professional sprayers, this is the kit.
What Is HVLP?
The traditional air spray guns are known as HPLV - high pressure, low volume. Alternatively, the newer HVLP spray guns atomise coatings by employing a high volume of air at low air cap pressure, typically in the 1 - 10 psi range compared to around 45 psi for conventional methods. This means the sprayed material has less velocity so is less likely to "bounce back". HVLP also produced a softer spray, reduces material waste and increases transfer efficiency.
However, because they require more cfm than conventional sprayers they need a larger compressor. Similarly to conventional spraying, HVLP spray requires adequate air pressure and volume at the air cap to produce the best results. Consequently, the same factors for minimising pressure drop and volume loss can be considered.
Don't forget it doesn't matter what size or style of spray gun and air compressor you own, keeping it clean is vital for avoiding blockages and keeping it performing at its very best. Therefore we suggest, this high quality cleaning kit for spray guns from SGS Engineering, you get everything needed to maintain your spray gun between uses with minimal fuss. The kit contains eight pieces, ensuring you have everything you need to give your spray gun a long life and continues to offer the best results.
Still not sure about your spray gun and compressor?
As well as designing our own range of air compressors and spray guns, SGS engineering works closely with various suppliers to ensure we only stock the very best air solutions. Our in house experts are always on hand for buying advice and to provide bespoke care, regardless of the application. Whether you’re just starting out on a new hobby or you have complicated commercial requirements, we’ve got the in-house experts to help. Call SGS on 01332 576 850 or fill out our contact form today. For all the purchasing advice and support you need.