Charlie99:
DA Aquamaster -- any comments on the how well the envirionmental seal kits work on balanced piston regs?
As I understand it, the seal on my Atomics B1 isn't much more than a bunch of Christolube jammed into the ambient pressure port, and held in place with a rubber cover. Any problems other than the expense of repacking with Christolube with each service?
Scubapro used their SPEC system prior to moving to the TIS system. SPEC (Silicone Protected Environmental Chamber) was messy to service but it was effective if properly maintained. The early SPEC regs (indroduced on the MK 3, Mk 5 and Mk 10) did not use a boot - just 1/16" holes in the ambient chamber and fairly thick silicone grease to prevent much leakage. Later SPEC equipped models (MK 10, Mk 15 and very early Mk 20's used a stiff rubber boot seated in a groove to hold the silicone in. The late Mk 15/Mk 20 boot was by far the best with a much wider boot that allowed for normal exapansion of the silicone and substantially reduced the amount of silicone lost over the dive season.
SPEC maintenence was not a problem for the occassonal diver, but if you dove a lot, you could find yourself needing to repack the ambient chamber mid season. If not, the voids in the chamber could become large enough to creater space for water to enter, freeze and cause the reg to freeflow. Packing was also a bit of an art to get it to happen with no voids in the first place. This was very hard to acheive on the Mk 10 due to how the piston sat in the reg body, but was much easier on the Mk 15 and Mk 20 givne that the piston head was in the swivel cap, not the body. Of course, in one of life's ironies as soon as SP got it perfected, they switched to the TIS system.
Personally, I liked the late model spec boots on the Mk 15's and early Mk 20's as they were very reliable, easy to pack and easy to maintain. However SP went with the silicone free TIS system to reduce the possibility of cross contamination on the bench once christolube came into use to accommodate 02 compatibility. This avoided the fairly high cost of packing with christolube, but was not as effective as a christolube packed ambient chamber would have been on a high performance reg like the Mk 20 and Mk 25.
In this regard, the Atomic approach of using a christolube filled ambient chamber is a more traditional, more conservative and more effective approach. The TIS system is adequate on the Mk 2, Mk 16 etc, but indaequate on the Mk 25 and the occurrence of freeze flows with the Mk 25 has seriously hurt the reputation of the Mk and Scubapro). So basically, you are in good shape with Atomic's system.
In general the use of silicone grease tends to be a bit more reliable than the silicone oil or alcohol used in many sealed diaphragm designs as if the diaphragm unseats or is punctured, the oil/alcohol leaks out, water enters and a freeze up is virtually guarenteed in cold water as water/heat transfer in and out of the ambient chamber is virtually nil.
Some sealed diaphragm designs are however dry designs. The Mk 17 for example uses a dry ambient chamber, a pressure transfer pad and a diaphragm with enough range of travel to avoid the need for a filler material to tranfser pressure. They are still vulnerable to water entry if the diaphragm is punctured, but they do not have the problem of the alcohol or oil in the ambient chamber expanding in high temperatures and unseating or rupturing the diaphragm and then leaking out. So it is a relatively simple and reliable design.