Servicing my own gear

[tbone1004]

bah, they don't break down any faster, they're just reactive with O2. Thankfully it's not really something you need to worry about unless you are diving nitrox mixes richer than 40%, which few do

 

[halocline]

The biggest thing is to make sure you have two tanks available, one at ~500-600 ish psi, the other full. First to seat the regs and get initial IP, the other to finish it off.

A full tank works fine. For checking IP at low tank pressure, you simply close the valve and tap the purge until the SPG reads whatever pressure you want.

Regarding the rebuild kit vs sourcing your own o-rings, consider the price. It's pretty common to pay almost $50 for a MK25 rebuild kit. For that same $50, you can buy practically a lifetime supply of o-rings for your MK25. You would still need to find seats and bushings, which unfortunately can be tough to find, but not impossible.

Still, this is one reason I prefer the MK5/10. Seats are everywhere; even the kits come with 3 seats, and often at least 2 of them will provide an appropriate IP.

 

[tbone1004]

it's more for setting the seat with the low pressure than checking IP, some regulators are particularly finicky if you send them full HP air straight off the bat

 

[wizbangdoodle]

Personally I only use 32%. I have not had any reason to go higher. I remember reading and being told that the higher percentage of oxygen could actually cause a fire in gear that was not cleaned properly. I suppose if you were using pure oxygen that may be true, but again, it was a dive shop and I'm sure they just wanted to sell more service.

 

[halocline]

it's more for setting the seat with the low pressure than checking IP, some regulators are particularly finicky if you send them full HP air straight off the bat

Since the force "setting the seat" (I don't really know what you mean by this) is IP, not supply pressure, I'm not sure what you are claiming is an advantage of having two tanks. The seat is never subjected to tank pressure.

 

[bl6394]

Since the force "setting the seat" (I don't really know what you mean by this) is IP, not supply pressure, I'm not sure what you are claiming is an advantage of having two tanks. The seat is never subjected to tank pressure.

Establishing the IP on a balanced first stage regulator at 500psi initially - such as the mk25 is the manufacturers recommended service procedure. It ensures the Ip is properly adjusted at minimal tank pressure. One then confirms minimal IP (for a mk25 1 to 5 psi) change as one raises the supply pressure to 3000.

From scubapro's point of view - the seat is set - after the first few cycles.

 

[bl6394]

Personally I only use 32%. I have not had any reason to go higher. I remember reading and being told that the higher percentage of oxygen could actually cause a fire in gear that was not cleaned properly. I suppose if you were using pure oxygen that may be true, but again, it was a dive shop and I'm sure they just wanted to sell more service.

By convention - any recreational scuba gear is compatible with any recreational Nitrox (< 40%) - except for the cylinder and valve - if exposed to pure O2 during partial pressure blending.

 

[bl6394]

A full tank works fine. For checking IP at low tank pressure, you simply close the valve and tap the purge until the SPG reads whatever pressure you want.
.

For the Mk 25 - the manufacturer 's service procedure involves cycling the purge several times to ensure lockup without drift or creep at 500psi Followed by a test at 3000 to ensure stable ip at full supply pressure.

In the shop - we use a hp regulator - in the field - you'll find two tanks make this easier

 

[tbone1004]

Since the force "setting the seat" (I don't really know what you mean by this) is IP, not supply pressure, I'm not sure what you are claiming is an advantage of having two tanks. The seat is never subjected to tank pressure.

first stage HP seat, not the second stage

 

[bl6394]

Resolution is a bit too coarse on that gauge. Other that provide better resolution in the 0 - 2 inch range are what you need if you are going to go that route.
...
Others like the bullet tool, which you do not need for your Mk25, will be very useful as ...

Good luck.

With respect - awap demonstrates the diversity of opinions you'll find when looking for information on the internet.

Regarding the 4 inch 5-0-5 magnahelic - it is functionally identical to the model sold on scubatools.com. Our shop has both - 0-2 and 5-0-5 and I find it completely serviceable for setting the cracking pressure. You'll form your own opinion.

Regarding the bullet tool on the MK 25 - scubapro recommends it's use to protect the knife edge and piston end. It ensures everything stays aligned when inserting the piston into the assembly. I can't speak to the alternative procees that Awap may use.

For $7.00 - I recommend its use.