What is Effective Working Pressure EWP on Pressure Cleaners - What is Maximum Pump Pressure -What is Operating Pressure

Maximum Pump Pressure (or Maximum Rated Pressure)

Max. Pump Pressure (in psi) is the maximum pressure the pump can take or which it is rated at – using in our case an Industrial Water Blaster. If you put too big an engine/motor on a pump and you drive it above this max pump pressure, you can damage or ‘blow up’ the pump. Maximum Pump Pressure is the Maximum Rated Pressure the pump can operate at.

This has nothing to do with the OPERATING PRESSURE (or ‘pressure at the nozzle’ or ‘working pressure’, except to know that the OPERATING PRESSURE must be below the MAXIMUM PUMP PRESSURE otherwise you will damage the pump and lose your warranty.

Most companies only give you this Max Pump Pressure and not the OPERATING PRESSURE – which is the important one. Unlike other companies, we put Operating Pressures on our Spec Sheets and other documentation because that is the important one – the REAL pressure.

This OPERATING PRESSURE can often be changed on the request of the customer depending on customer needs or application.

Example: A pump might have a MAXIMUM PUMP PRESSURE of 3500 psi, 15 lpm which may require 10hp to drive it to this pressure. We might put a 10 hp engine/motor on it but still only set it up at an OPERATING PRESSURE og 3000 psi, even though there is enough pressure to drive it to 3500 psi.

Why? Because for most general cleaning of painted surfaces you don’t want a set-up pressure of more than 3000 psi because you will damage the paint.

Now if you only put a 5 hp motor/engine on this pump which requires 10 hp, you will still get 15 lpm running at the same revs (because for every stroke of the piston a certain volume of water is pumped which does not change) but the pressure will only get to half of 3500 psi, which is an OPERATING PRESSURE of 1750 psi.

Operating Pressure in Industrial Pressure Cleaners

As we’ve explained above, the OPERATING PRESSURE (or Set-up Pressure) is the pressure at the nozzle, which can be read on a proper Pressure Gauge fitted to the machine.

Operating pressure is firstly dependent on the power of the engine/motor that drives it and secondly on the application.

EWP – Effective Working Pressure

*EWP = Effective Working Pressure (using a Turbo Nozzle) – is a theoretical figure. Because the water stream from a turbo jet does not fan out and the force of the jet stream does not dissipate as is the case with a fan jet/nozzle by the time the water hits the cleaning surface, the concentrated pencil jet stream hitting the surface is equivalent to a cleaning effect around

60% higher than with a fan jet.

And because the turbo nozzle /roto jet spins in a circular motion at a very high speed, it still covers the same surface area as with a normal fan jet/nozzle giving you:

  • Better pressure where it hits the surface (~60%)
  • ~60% better cleaning
  • Same cleaning surface area
  • Much faster cleaning speed

But it is not really 6960 psi. It really says: If you compare a normal fan jet at 4350 psi’s performance, a Turbo Nozzle’s performance is 60% better and it is almost like using a fan jet at 6960 psi.

EWP is very confusing and we only quote that figure because some opposition companies do that – giving people a false sense of expectations from their Industrial Pressure Cleaners – which is even more of an issue when it comes to Domestic Pressure Cleaners which are not fitted with pressure gauges.

Which are fitted with some sort of gauge which doesn’t give you psi, just numbers which can be mistaken for psi and again misleading the buyer.

We are slowly deleting EWP off all our documentation.

If you need a pressure cleaning solution that works, call us TODAY.

Contact us Today!

Or call us on

1300 378 872

We can help you with


With our full range of pressure washers available, we understand that owning your own pressure washer is the right fit for your business. Talk to our team today to purchase outright a pressure cleaning solution tailored made for you.

Find out more


We offer a wide range of pressure washers for rental directly to the public at competitive rates, meeting your every pressure washer need.

Find out more

Service and Repairs

Our factory-trained technicians will repair and service all pressure cleaners either in our workshop or on your site.

Find out more

Spare Parts

We can provide a full range of pressure cleaner and pump parts and service kits supplied at competitive prices for all our models. As well as for a range of our competitors' makes and models of water blasters.

Find out more

Technical Support

We don’t just sell pressure cleaners. We have dedicated engineers and technicians that design, manufacture and maintain one of the best pressure washers on the market With a dedicated technical support team, we can help you find the best solution for your pressure cleaner problems.

Find out more


You can access our FREE online training covering Class A machines. This offers great value to end users ensuring safe operation of your water blaster. As well as ensuring your training records are up to date.

Find out more

Trusted by leading companies