Not heating, but plumbing related

ChrisJ

I'm trying to repair our pressure washer and I'm having issues with the unloader.
The reason I'm posting is something really strange happened with the brass fitting on the inlet side, but not the outlet side.

The brass was attacked by something and is a brownish silver color and has a ton of mineral buildup and even erosion. None of this took place on the outlet side which is physically connected to the inlet piece. In fact, the outlet fittings inside and out look like brand new, bright yellow brass.

What gives? It probably doesn't matter, but the machine is rated 2600PSI @ 3GPM.

ChrisJ

Looks like I'm wrong, the inlet section was never a bright yellow color, not sure what it's made out of now but it sure got attacked over the years.

Best I can tell, it's aluminum. Why would they couple aluminum with brass!?!

Mark Eatherton

Yellow brass is considered a dielectric material. You can connect copper to steel through it and not cause degradation of the lesser of the two noble metals (iron). It MUST be yellow brass, otherwise all bets are off.

Must be some tough aluminum to handle that kind of pressure.

3 GPM at 5,998 feet of head....

ChrisJ

Mark Eatherton said:

Yellow brass is considered a dielectric material. You can connect copper to steel through it and not cause degradation of the lesser of the two noble metals (iron). It MUST be yellow brass, otherwise all bets are off.

Must be some tough aluminum to handle that kind of pressure.

3 GPM at 5,998 feet of head....

The aluminum is on the return side, so that's only seeing 60PSI or so from the garden hose. The brass see's the 2600 PSI.

SWEI

The pressure washer pumps I have worked on are all brass, but they are small commercial units (CAT and Comet come to mind.)

If it's really made out of aluminum, I would suspect water pH or chlorides.

ChrisJ

SWEI said:

The pressure washer pumps I have worked on are all brass, but they are small commercial units (CAT and Comet come to mind.)

If it's really made out of aluminum, I would suspect water pH or chlorides.

I bought this from my boss a few years back, I believe it was considered a commercial machine but could be wrong. I think he paid around $800 for it.





And I believe this is the same pump, or at least the same style. It's a Annovi Reverberi brand

Gordy

Are you sure it's not SS instead of brass Chris?

ChrisJ

Gordy said:

Are you sure it's not SS instead of brass Chris?

The upper half I'm pretty sure is brass.
The lower half I think I found somewhere that it's aluminum. There are SS parts like the piston, but I think the main unloader body is brass.


Here's the replacement I bought on Ebay. I started tearing the old one apart to try and get it working because the original part number is $352+ everywhere. This morning after waking up I realized I didn't need the original part and then somehow stumbled on a modern version of the same one so it'll bolt right up without any fittings or adapters.

Gordy

Do you,or did the original owner use the detergent dispenser? Or is there even that attatchment?

ChrisJ

Gordy said:

Do you,or did the original owner use the detergent dispenser? Or is there even that attatchment?

There's an injector that goes on the outlet of the unloader, so that never passes through it.

I never did, not sure if he did or not.