Environmental Seal?
- Thread starter Loewely
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They can be very important in cold water and also in very dirty water.
The type of environmental seal used can be a variation of a few basic designs.
Some diaphragm regs use another rubber diaphragm between the ambient pressure chamber and the surrounding water. The sealed ambient chamber is then filled with alcohol or a silicone oil to transmit the ambient pressure to the internal parts of the reg. They work well until they leak and in hot weather the liquid can expand and force some of it out through the seal. When they do leak and get water in them, they are almost guarenteed to freeze up in cold water.
Piston regs normally use a silicone filled environmental chamber covered with a rubber boot. Some designs with a larger flexible boot approach the degree of environmental sealing that is achieved with a alcohol/silicone oil filled and diaphragm sealed chamber. With piston regs though, the environmental chamber is filled with either silicone or an O2 compatible substitute. The combination of the silicone and, in most cases, a rubber boot keeps the water out of the ambient chamber and away from the internal parts of the reg.
But again silicone grease can be lost over time and a great deal of care is needed when packing and assembling the reg if you are to get 100% effective results. Many techs don't know how or take the time to do it right and many don't like to have to clean the old silicone out during annual servicing.
Another approach to environmental sealing technology in piston regs is to use an air filled chamber protected by a one way valve and pressurized to match the ambient water pressure using diaphragm and pin to operate a schrader valve to bleed air from the IP chamber into the ambient chamber. Great design but overly complicated for my tastes. It adds a great deal of complexity and a potential failure point to what is other wise a simple and bullet proof design.
Essentially the same thing is accomplished in Sherwood first stages with a small bleed hole from the IP chamber to the ambient chamber that keeps air in the ambient chamber. It is however not 100% environmentally sealed and water can enter the ambient chamber during a rapid descent. The small hole to the exterior then makes rinsing this water out very difficult. You also have what appears to be a small leak through out the dive and the well intentioned buddies letting you know about it can be annoying.
On the most recent Scubapro regs, they use a Thermal Insulating System consisting of a polished piston stem, a teflon coated mainspring, a small rubber boot that flexes to break any ice off the exposed part of the piston stem and a insulating cover for the piston head to both prevent and limit ice formation. On the Mk 2 it works great, but with the Mk 25 freeflows still occur for many divers in water colder than about 40 degrees. The Mk 16 is a diaphragm reg but uses a similar TIS kit and it also works well in cold water.
Basically all of the designs have advantages and limitations so you end up with some compromises one way or the other. If your diving is always in warm and clear tropical water you won't miss an environmental kit if your reg does not have one.
The type of environmental seal used can be a variation of a few basic designs.
Some diaphragm regs use another rubber diaphragm between the ambient pressure chamber and the surrounding water. The sealed ambient chamber is then filled with alcohol or a silicone oil to transmit the ambient pressure to the internal parts of the reg. They work well until they leak and in hot weather the liquid can expand and force some of it out through the seal. When they do leak and get water in them, they are almost guarenteed to freeze up in cold water.
Piston regs normally use a silicone filled environmental chamber covered with a rubber boot. Some designs with a larger flexible boot approach the degree of environmental sealing that is achieved with a alcohol/silicone oil filled and diaphragm sealed chamber. With piston regs though, the environmental chamber is filled with either silicone or an O2 compatible substitute. The combination of the silicone and, in most cases, a rubber boot keeps the water out of the ambient chamber and away from the internal parts of the reg.
But again silicone grease can be lost over time and a great deal of care is needed when packing and assembling the reg if you are to get 100% effective results. Many techs don't know how or take the time to do it right and many don't like to have to clean the old silicone out during annual servicing.
Another approach to environmental sealing technology in piston regs is to use an air filled chamber protected by a one way valve and pressurized to match the ambient water pressure using diaphragm and pin to operate a schrader valve to bleed air from the IP chamber into the ambient chamber. Great design but overly complicated for my tastes. It adds a great deal of complexity and a potential failure point to what is other wise a simple and bullet proof design.
Essentially the same thing is accomplished in Sherwood first stages with a small bleed hole from the IP chamber to the ambient chamber that keeps air in the ambient chamber. It is however not 100% environmentally sealed and water can enter the ambient chamber during a rapid descent. The small hole to the exterior then makes rinsing this water out very difficult. You also have what appears to be a small leak through out the dive and the well intentioned buddies letting you know about it can be annoying.
On the most recent Scubapro regs, they use a Thermal Insulating System consisting of a polished piston stem, a teflon coated mainspring, a small rubber boot that flexes to break any ice off the exposed part of the piston stem and a insulating cover for the piston head to both prevent and limit ice formation. On the Mk 2 it works great, but with the Mk 25 freeflows still occur for many divers in water colder than about 40 degrees. The Mk 16 is a diaphragm reg but uses a similar TIS kit and it also works well in cold water.
Basically all of the designs have advantages and limitations so you end up with some compromises one way or the other. If your diving is always in warm and clear tropical water you won't miss an environmental kit if your reg does not have one.
rescuediver009
Contributor
One other thing to add is that along with dirty water it is beneficial in helping you keep your reg clean when you dive alot of salt. Most people will not take the time to properly rinse the inside of the first stage that is exposed (main spring etc.) The seal makes this easier.
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