Rust inside MK25/A700 after using with steel tank

[aurax]

Hi Friends,

I bought 2 months ago a MK25/A700/R395 kit for recreational diving.

Yesterday i went diving with 15l steel tank. in the middle of the dive i found it a little hard to breath but it got released after 2 seconds.

when I got out of the water i found out that the first stage is full of rust in the Yoke connector (where the filter is), and I'm talking about LOTS of rust.

so i cleaned it with fresh water (not salty) and connected it to an aluminum tank and put allot of pressure to clear the water.

Then i noticed that the rust is also in the second stage !! I know that no liquids suppose to pass through this unit!

Is my MK25 damaged? I'm planning to send it tomorrow for a maintenance but just like to make sure that it's not damaged or will become permanently damaged.

Thanks!

 

[ajduplessis]

Did you buy new? It is difficult to imagine rust forming this quick unless you rinsing/maint really sucks. The rust in the second stage could have come from the already rusted first stage, or rust from within the tank. I would service both stages and also inspect the tank.

 

[aurax]

It's new, but the rust didn't came from the reg, it's from the tank for sure.

But is it common that rust inside tanks can pass to reg first and second stage?

 

[halocline]

I don't think it's very common; usually the crud gets stopped by the filter, and sometimes I've seen some crap in the HP chamber. But, don't worry about it, just get the reg serviced, make sure they clean the hose too, and you'll be fine. If it was a rental tank, you could try to get the place that supplied the tank to pay for it, but that might be tough. At the least make sure they know their tank is contaminated.

You don't need new rebuild kits; a good tech can just take the reg apart, clean both stages, and put it back together. The seat in the MK25 lasts a long time. I don't know too much about the A700 but I'd bet the seat in it is barely worn. This is the sort of situation where if it was my reg, (I do my own service) and the seats/o-rings were two months old, I would not replace them.

If the tech says something about IP creep with a HP seat that's re-installed, he's thinking of the older knife-edge piston seats. The MK25 piston has a rounded edge, and locks up really well with the current seat. You might get a few PSI of creep initially when it's put back together but I would bet that it would completely disappear after a dive.

 

[matsat64]

Tank is the problem, I have an S40 sitech new I will trade you?

 

[aurax]

Thanks man!

I'm going tomorrow to put it in services. I will request for a total cleanup of the two units.

Do you think i will need to replace filter since water managed to pass through this one?

 

[redacted]

Thanks man!

I'm going tomorrow to put it in services. I will request for a total cleanup of the two units.

Do you think i will need to replace filter since water managed to pass through this one?

The filter is designed to stop larger particles, not the rust suspended in water you apparently encountered. The filter would best be replaced. In the US, most shops would insist on replacing with full service kits rather than just a filter.

 

[sphillips3]

If you brought this to me it would get a full service, including complete disassembly, cleaning, full service kit (which always includes a filter) and reassembly and testing.

As others have said, the rust came from the tank - the majority of the reg is chrome-plated brass, which cannot "rust". In any event, brass corrosion is green, steel corrosion (rust) is brown.

 

[Zung]

The filter is a separately orderable part, #01028109, your LDS willing. It costs but a few bucks. It makes no sense to waste 3 service kits (1 first plus 2 seconds).

 

[sphillips3]

The filter is a separately orderable part, #01028109, your LDS willing. It costs but a few bucks. It makes no sense to waste 3 service kits (1 first plus 2 seconds).

The problem is that once the rust has gone past the filter (OP reported rust in second stage) then the iron oxide particles will act as an abrasive, causing premature wear of the plating on the inside of the piston cap. In my view a complete service is not a "waste" but a prudent step to take to help ensure the long-term performance of the gear.