Why isn't my foam cannon from another brand working properly?

The short answer, either the wrong nozzle size, or dirt in the nozzle!

Test different nozzles/foam guns, and clean the nozzle.

More complementary information below, if desired

Nozzle size

If the machine chases or pulses during use, this is most likely because the nozzle/aperture is too small. To find out if that is the cause, test several types of accessories. When the machine works normally with some nozzles, the fault must lie with the accessories and not the machine.

A nozzle that is too small causes the machine to reach maximum pressure and switch off whist in use. When the water continues out of the nozzle, the pressure drops and the machine switches on again. When the nozzle is a little too small, this happens frequently and turns into a "pulsing sound" or jerky reaction from the pump.

Foam cannons from AVA are adapted to the various models' pressure and water volume, while other brands often have a universal nozzle that will fit many brands and types. The most typical thing is that a variant is made for hobby washers and one for professional washers. Some manufacturers state size, while others do not. We know from experience that the same type of foam cannons can have a variation in nozzle size due to the tolerances they are made to.

Dirt

Some people find that a foam cannon has worked well, and then one day causes trouble. This may be due to a partially blocked nozzle; for example, a small grain of sand that has settled in the nozzle opening. This can be solved by rinsing the cannon in warm water, and possibly using a cleaning needle or something similar. This needle is included on the back of the user manual.

The most common reason for issues in cases like this is that the nozzle is made marginally too small due to the bloackage. The machine will then work when there is low voltage in the home, while it will not work when the voltage rises. The voltage also varies if you connect the washer close to the fuse box, or if you are further away, or use an extension cable in addition.

This can again be confirmed with a test: if the other accessories work, we can only blame the nozzle.

If you want some technical specification:
We use 1.35 nozzles on our foam cannons.

What we have measured on other brands supplied for consumer pressure washers varies from 1.21 to 1.32. Often these are intended to be 1.25 or 1.3, and due to wide tolerances on nozzles (the nozzle itself inside the foam cannon) we see large variations which mean that one can work while another of the same type does not. By going up to 1.40 in nozzle size, these problems will disappear. Smaller washers have no problems coping with such an increase in nozzle size and therefore we have stopped supplying 2 different nozzle sizes on our own foam guns, up to P80.

A high-pressure washer has a pump which, at a given speed, has a freely flowing amount of water. When you insert a restriction/nozzle into this water flow, the pump/motor has to work harder to push through a corresponding amount of water. This work results in increased pressure in the water. See the attached images at the bottom of the page for reference to the aperture/nozzle part.

The pressure sensor in AVA high-pressure washers is electro-mechanical and consists of a spring-loaded piston and a microswitch. When the pressure in the pump exceeds the maximum working pressure, the pressure on the piston will overcome the force in the spring and activate the microswitch (which cuts the power to the pump).

Variations in temperature, tolerances on dimensions and material properties mean that we operate with +/- 4% when this switch is activated. This is the reason why the foam cannons can work well on some machines but not others. All our equipment takes this variation into account and only a few of the nozzles will be close to the maximum working pressure.

We are currently working on translating and rewriting all of our articles into English from the original Norwegian. Whilst we are proud of the quality of our language skills here at AVA, we are aware that there may be some slightly odd syntax and wording present in the articles that have been translated. The approach we have taken to this translation process is in order to get as much information as possible out to our customers in a timely fashion. Thusly the ongoing revision and updating of these articles by our British-Norwegian team will include slight changes to how the text is put together in order to bring it more into line with correct British English.