Repair Guide

Which pressure washer pump manifold material is best ?

Did you know that not all pressure washer pumps are built the same ?

Basics :

Each pressure washer pump material has a unique set of properties the have both advantage and disadvantages. The common materials used for pressure washer manifolds are:

• Plastic - PA6633GS (INGREDIENTS poly-acetate 66 % and glass fibre 33%)
• Aluminium 
• Brass - an alloy of copper and zinc
• Stainless steel

Plastic

This is cheap and for some in some cases will be the best material ! You may be amazed that plastic could be used to encase 1500 psi / 100 bar pressure water. It can if you mix fibres in with the plastic in the same way vehicle bodies can be made of resin if you mix in glass fibre. The plastic material is limited to around 100 bar pressure. If you don't use your pressure washer much and can do your job with this pressure then this is the one for you. Why ? because if you are not using your power washer the pump may start to corrode (oxidise / rust) and then seize. This only really applies to aluminium pump that have not been anodised. Used on Karcher K1-K4 series

Pros:
cheap
does not rust

Conns:
pressure limit
shorter lifespan

Aluminium

Aluminium is stronger than plastic so you can have upto 150 bar or 2000 psi pressure as a guide. Its cheaper than brass too and easy for the factories to machine. If your manufacturer has cut corners then it wont be anodised. Anodisation uses electric current to create a protective layer on the surface of the metal. See wiki anodizing
Karcher K5 and K6 series, most chinese machines and most nilfisk alto pressure washers (nilfisk usually anodise)

Pros:
cheapish
does not rust if anodised (well not for a while)
higher pressure rating than plastic

Conns:
rusts if not treated so not suitable if you dont use your power washer very often

Brass

This is the most common industrial material used in most commercial pressure washers and a few select domestic machines. Karcher have the K7 series and Nilfisk have the P150 domestic pressure washers. The pressure range can be upto 4000 psi / 250 bar. Brass is heavy and prone to cracking if abused

Pros:
strong
does not rust - ever !
higher pressure rating than plastic and aluminium
great if you need extra pressure or dont use your machine much

Conns:
expensive
cracks

Stainless Steel

This is reserved for drain jetters and wet cutters using extreme pressures of 15,000 psi or more ! athe pumps with stainless steel bodies can be over £15,000 too....

Pros:
strong
does not rust - ever !
higher pressure rating than plastic and aluminium and brass
great if you need extra extra extra pressure or dont use your machine much

Conns:
very expensive



Google