There are so many different airless sprayer models available in the market place worldwide varying from entry level price through to airless spray pumps selling for thousands of dollars.
What is the real difference between all these different brands and models of airless spray painting units offered for sale?
The primary measurement of airless sprayer performance compared to all competitive airless sprayers in a reasonably similar performance bracket is actual flow or in other words the maximum fluid output the pump is capable of delivering.
A secondary and usually very minor variation between different airless sprayer performance specifications is maximum pressure. An important aspect to understand regarding maximum pressure especially with airless sprayers is the maximum pressure figure which is usually stated in marketing material is the static pressure which is only achievable while the airless spray machine is not actually pumping or spraying any material. Physics cannot be avoided and as flow increases pressure will decrease. The more flow an airless sprayer is required to deliver dictates that pressure must continue to decrease as the flow is increased.
Actual airless sprayer motor size is most likely really meaningless unless you have two airless pumps using the same size pump design and the same gearing. If one airless pump in this type of scenario had a larger motor and the additional cost was relative then a larger motor may be a benefit.
With flow being the major consideration in comparing, choosing or specifying a correct airless sprayer model what specifications can be used to properly compare competing models?
Most airless spray tip manufacturers specify a flow rate for a given airless spray tip size at a specified pressure. For example let us say that a 0.017 inch 0.43 mm spray tip which is arguably the most common water-based airless spray painting tip used flows an approximate flow rate at 100 bar or 1500 PSI of .98 of a litre per minute or .26 of one US gallon per minute. Using this scenario an airless spray pump capable of achieving a maximum flow of only .25 US gallon per minute would not be able to support a 0.017 inch spray tip with this flow. Even an airless sprayer capable of a maximum 1 L per minute flow rate would not usually be expected to be able to maintain pressure at this flowrate especially as incremental spray tip wear occurs.
A meaningful specification for assessing the real capability of an airless sprayer will be a specified flow rate or specified maximum airless spray tip size at the specified pressure the actual airless pump is able to maintain while of delivering this amount of fluid flow. Unfortunately most airless sprayer manufacturers have ceased to specify the actual pressure that is maintained through the maximum size airless spray tip capability advertised for that machine. The specifications that tend to be advertised these days is maximum attained pressure, (there is rarely a significant difference with this rating), maximum output and maximum airless spray tip size.
These latter two specifications can be cross checked to provide an indication that the specs might be theoretical or actual working figures. Taking specifications from a popular electric airless sprayer which is advertised as a .85 US gallon per minute or 3.2 L per minute maximum output specified as a maximum airless spray tip size of 0.027 inch. At 100 bar or 1500 PSI a 0.027 inch spray tip should flow approximately .66 US gallons per minute. Subtracting the advertised maximum flow output from the 1500 PSI approximate flow rate of a 0.027 inch spray tip shows that this particular airless sprayer model is advertised with a maximum working output capability of 0.19 gun per minute less than its advertised maximum output. Next take the figures from a competitive popular airless sprayer model also specifying a maximum airless spray tip size of 0.027 inch but this model specifies a maximum delivery of 0.7 gallons per minute. Repeating the above equation indicates that at 0.04 gallons per minute difference this airless sprayer has far less buffer between the advertised maximum delivery and the maximum airless spray tip size is advertised of supporting.
Arguably if the first model employs a similar size motor, offers a comparable level of features and accessories and the maximum static pressure is within 500 PSI of each other then the real decider may well end up being price.