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Selecting the Correct Airless Spray Pump

Choosing the right airless spray pump comes down to one thing above all else: knowing your paint. Get that right, and everything else – pressure, pump type, spray tip – falls into place. Get it wrong, and you’re looking at poor atomisation, wasted material, and a finish that won’t hold up.

This guide walks you through exactly how to make that call, step by step. And if you’d rather skip straight to browsing, our full airless spray equipment range covers pneumatic, electric and hydraulic pumps for every application from touch-up work to heavy industrial coating.

The Three Types of Airless Spray Pumps

All airless pumps do the same basic job – pushing paint through a hose at high pressure so it atomises at the tip. What differs is what drives that fluid section:

Pneumatic pumps – driven by a compressed air motor. The most flexible option for high-solids, heavy-duty coatings, with the widest pressure range of any pump type.
Electric pumps – driven by a 220V motor. Lightweight, no compressor required, ideal for decorative and fine-finish work.
Hydraulic pumps – self-contained units powered by integrated petrol, diesel or electric drive. Built for portability where there’s no power source on site, right up to large-scale site establishment and heavy-duty industrial projects where you need a standalone, high-output system that isn’t reliant on separate compressed air or mains power.

Knowing the difference is a good starting point – but it’s not enough on its own. The pump type you choose ultimately comes down to the paint you’re spraying.

Matching Pump Type to Your Paint

The single biggest factor in pump selection is volume solids – the percentage of solid material in the paint once it’s dry.

Below 65% volume solids – electric or hydraulic pumps are generally suitable.
Above 70% volume solids – pneumatic pumps are advisable, since higher-solids coatings need more pressure and volume to atomise properly.

As a general rule of thumb, this also lines up with project scale: smaller decorative and touch-up jobs tend to use lower-solids paints (better suited to electric units), while large-scale industrial and protective coating projects typically involve higher-solids, more viscous paints – which is where pneumatic and hydraulic pumps earn their keep. Use volume solids as your primary guide, and project scale as a useful sanity check.

Beyond volume solids, a few other factors will influence your final choice:

Viscosity – thicker paint resists flow inside the hose. A higher-pressure pump pushes it through more effectively.
Hose length and cold paint – long hose runs or cold (higher-viscosity) paint may call for a higher-ratio pneumatic pump to maintain pressure at the gun.
Pigment and orifice blockage – heavily pigmented paints can block smaller spray tips, which means sizing up to a larger orifice – and, in turn, a pump that can deliver the higher volume output that larger tip demands.
Required coating thickness – if you need to build up a thick coat, a higher-volume-output pump gets you there faster.

Understanding Pressure Output and Ratios

Here’s where a lot of confusion creeps in. Most paint only needs 80-180 bar to atomise properly at the gun. So why would you ever need a pump capable of producing more than that?

Pump type dictates the available range:

Electric and hydraulic pumps typically output 210-230 bar.
Pneumatic pumps range anywhere from 180-500 bar, depending on the model.

That headroom matters once you factor in hose length, paint viscosity, and tip size – all of which create resistance that eats into your usable pressure. A pump rated well above your minimum atomisation requirement gives you the reserve capacity to still hit the gun cleanly under real working conditions.

Pneumatic pump ratios (30:1, 63:1, 95:1, and so on) describe this relationship directly. The number represents how many bar of fluid pressure the pump produces for every 1 bar of air pressure supplied. A 63:1 pump, for example, produces 63 bar of fluid pressure for every bar of air pressure fed into it. Higher ratios mean more available fluid pressure – useful for high-viscosity coatings, long hose runs, or larger tip sizes.

Don't Forget the Spray Tip

Your spray tip is one of the smallest components in your setup, but it plays one of the biggest roles in the outcome. For most industrial applications, your paint’s data sheet will recommend a tip size – but a data sheet alone doesn’t account for hose length, ambient temperature, or pigment density, all of which can shift the ideal tip size up or down.

For a full breakdown, read our guide: How to Choose the Right Size Airless Spray Tip.

Quick Decision Checklist

Before you buy, run through this:

What’s the volume solids % on my paint data sheet?
Is this a small decorative job or a large-scale industrial application?
How long are my hose runs, and will I be spraying in cold conditions?
What tip size does my data sheet recommend – and does pigment density change that?
Do I have access to a compressor, or do I need a self-contained unit?
What coating thickness am I trying to achieve, and how quickly?

FAQS

Can I use an airless sprayer with varnish or stain?

Yes – most airless sprayers handle varnishes and stains well, since these coatings tend to be thinner and lower in volume solids than paint. An electric pump is usually sufficient, though always check your product’s data sheet for specific viscosity and tip size guidance, as some stains contain fine pigments that need a smaller tip.

What happens if I use too low a pressure for my paint's volume solids?

You’ll get poor atomisation – the paint comes out in an uneven pattern with visible tails or “fingers” instead of a smooth fan, and heavier coatings may spit or surge at the gun. This is one of the most common causes of a patchy finish, and it’s usually a sign the pump can’t generate enough pressure or volume for the coating you’re using.

Do I need a different pump for water-based vs. oil-based paint?

Not necessarily – most airless pumps handle both, provided the fluid section is compatible (check your pump’s specifications). What matters more is matching pressure and tip size to the paint’s volume solids and viscosity, regardless of whether it’s water- or oil-based.

Can one pump handle multiple paint types?

Generally yes, provided the paints fall within the pump’s pressure and volume solids range – most contractors use a single pneumatic or hydraulic pump across a range of coatings by adjusting pressure and tip size per job. One thing to check first: your spray tip’s output is rated in litres, so make sure your pump can actually deliver enough volume to keep up with the tip you’re using – this becomes especially important if you’re stepping up to a larger tip for a heavier coating, since a pump that can’t supply enough volume will lose pressure at the gun even if its pressure rating looks adequate on paper.

Ready to Choose Your Pump?

Whether you need the fine-finish precision of an EP270 electric pump for decorative work, or the higher-volume output of a pneumatic unit like the Storm SX for large industrial projects, Storm Machinery’s full range covers every scenario above.

Browse our full range of airless spray pumps and equipment →

Still not sure which pump suits your application? Our sales engineers are on hand to help you match the right equipment to your paint and project – get in touch and we’ll walk you through it.