Saturday, August 8, 2015
Pressure Washer Lance Nozzles - what you need to know
Nozzles fitted to Power Washer Lances
Are they all the same ?
NO THEY ARE NOT SO PLEASE READ ON......... !
How do they differ ?
Size, Shape, Connection and Function
Size
Not all nozzles are a circular hole and many are eliptical so you cant always specify a diameter. The industry standard is a number that relates to the total CSA (cross sectional area). In domestic machines this is often 035 and industrial pressure washers this is often 055
Shape
The common types are fixed, variable and turbo.
Fixed are usually small stainless nozzles 10x20mm
with 1/4 male BSP thread
with flat face for clamping onto the Karcher industrial Lance
with 1/4 male BSP threadwith flat face for clamping onto the Karcher industrial LanceVariable plastic covered cylinder 70x30mm
Turbo plastic covered cone 80x50mm
Internal Turbo nozzle components - turbine nozzle and ceramic seat
Connection
- UK industrial connection is usually a 1/4 inch BSP male thread on the nozzle that screws into the lance
- USA industrial connection is often by the click or snap on system via a snap fitting on the lance
- Domestic Nozzles are usually part of the lance extension and so fit to the gun via some kind of plastic bayonet
Function
Fixed no function.
Variable have a number of components assembled into a nozzle.The iternal parts are often brass and covered in a plastic sleeve. Most variable nozzles can twist to change the jet pattern from a thin pin-prick to a wide v-shape. Some variable nozzles also pull / push for high and low pressure settings. The jet is formed by a grub screw drilled with a precise hole. This creates the pin-prick jet that can be changed to fan as 2 stainless plates come together squashing the jet.
Turbo also known as 'dirt killer' 'roto-power' 'power-speed' 'dirt-blaster' are pin-prick jets that oscillate at high speed. The common design uses a cone chape housing to hold a loose turbine. The turbine has a precise sized jet at the exit and fins at the back entrance. As water flows through the lance it enters the cone shaped turbo nozzle housing and hits the turbine fins. This make the nozzle oscillate. The nozzle is hollow so water exits the turbo nozzle through the center of this moving nozzle. You will only see the cone of water but it is in fact a single jet moving at high speed. Turbo nozzle wear out ! Domestic turbo nozzles should last 10-20 hours and insutrial turbo nozzle 100 hours. Industrial Turbo nozzles last longer because they use stronger materials like stainless steel and ceramics.
How does the nozzle set the pressure ?
The spill valve operates at approx 20% higher than specified pressure washer operating pressure. If you have any lance issues then the pressure could be running higher than specified (machine running at same pressure as spill valve operation pressure)
Your machine produces a fixed flowrate of water (maybe 8 litres per minute) and your nozzle is a fixed size. the diameter of the nozzle determines the back pressure. A piece of debris could further close your nozzle orifice and increase the back pressure. Using a new lance that has the wrong nozzle fitted can also cause this issue.
Lances for Karcher
Lances for Nilfisk
Pressure Washer Lances
Lances for Karcher
Lances for Nilfisk
Pressure Washer Lances
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