Backup regulator set advice

[Stu S.]

I do not own backup gear, except for an extra mask. And, the only thing I've had fail is SPG's. That's two while diving and one failed in a shop. It may be worth carrying a spare. Last time, the hose blew up prior to a dive, and Capt. Mike passed me a "boat" regulator set.

At no time did any of this become a disister.

 

[diver 85]

How 'bout breaking a SP rubber strap that holds the dust cover on your 1st stage while leaving the dock(@ nite) on the Fling--- a 110' live aboard in the Gulf of Mexico---heading for the Flower Gardens, 125 miles offshore...........Naturally I lost it under the bench, everybody(30 divers on board) & his brother had their dive gear set up on tank racks with tons of dive bags underneath...A what $1 part????.....Went to my 2nd 'backup' regulator & did not miss a thing(dive)..Thankfully found it late the next & just stayed with my backup.......Very thankful I brought the 2nd one.......IMO, get a 2nd set.........

 

[ericpitar]

Considering the weight issue (thanks for mentioning Mattboy) and considering the MK25 is quite known for reliability, I might just pass on the spare 1st stage (unless i find a reeeal bargain) and get the following:

--extra spg
--swivel o-ring
--Spare 2nd stage
--spool o-ring
--wrench

what do you guys think?

A few more questions:

1-an adjustable wrench should be sufficient, correct?
2-How does one detect "IP creep?"
3-How important is that removalbe plastic cap on the back of the MK25? I lost mine in a trip but havent bothered replacing it after a veteran diver said it's mere cosmetic.
4-Are the spool and swivel o-rings simple enough to replace that a non-tech may be able to do it without a problem? Maybe one of you can send me a basic manual or illustration to show where in the world these o-rings belong to?

My current set again is MK25/R109BA/R190


Thanks again!

e

 

[DA Aquamaster]

You will need two wrenches to remove the SPG - one to hold the gauge and one to turn the fitting. Personally I'd skip the extra SPG, buy a good brass one and don't worry about it as they are pretty bullet proof.

The HP spool is easy to replace. Just remove the SPG fropm the hose an the spool will be stuck on either the hose or the SPG. Just pull it out with your fingers (or with a pair of needle nose pliers if it is slightly stuck with salt, etc. They come in two basic flavors, one that is straight and another that has a flange in the middle and both cost about $7. Lubricate the o-rings with either christolube or silicone grease.

The trim boot on the Mk 25 is mostly cosmetic, athough it probably does protect the seat retainer to some extent.

IP creep is detected most easily with an IP gauge. You can buy one from leisure pro or a similar on-line source that plugs into the BC inflator hose.

Or you can go to the local hardware store and dive shop and make one. You need your basic shop compressor or air tank gauge (about $10-$12) with a zero to 180-250 psi range which should come with a 1/4 NPT thread. Buy a 2" female 1/4NPT to female 1/4 NPT nipple and install the gauge on one end using pipe thread tape and install a 1/4 NPT to BC QD fitting from your local dive shop on the other end of the nipple.

A normal first stage will have a stable IP in the 120-150 psi range that drops about 10-15 psi when you purge the reg. When you release the purge the needle should quickly swing back to the original IP and remain their with little or no creep. If the needle continues to move upward after the initial swing, you have a leaky HP seat.