Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.
Benefits of registering include
Ability to post and comment on topics and discussions.
A Free photo gallery to share your dive photos with the world.
I use my butt dump to vent air from my BC nearly all of the time. I don't actually remember the last time I used my shoulder dump or my inflator hose. I have never yanked on my inflator hose to vent air, would have to try this to make sure it worked.
Usually the "Butt Dump" is the OPV, but I have no doubt, given all the wacky designs for BCD's that have been produced there are "butt dumps" that aren't OPV's
Every BCD will have at least one OPV, they act to keep the BCD from bursting if over inflated.
Usually the "Butt Dump" is the OPV, but I have no doubt, given all the wacky designs for BCD's that have been produced there are "butt dumps" that aren't OPV's
Every BCD will have at least one OPV, they act to keep the BCD from bursting if over inflated.
just watned to make sure. My back inflate is horseshoe shaped and has a OPV(butt dump) on each side. I use them almost exclusively. The shoulder dump never, I do use the inflator part to vent when decending and ascending. I start my drop verticle and empty the bladder. I end my ascent from the safety stop to surface vertically. That is the way I was taught.
I have seen OPVs on the shoulder opposite the inflator and OPVs (butt dumps) on both sides or only one side, I like mine the best.
My students use the lower rear valve on the bc roughly 10 to 1 over the inflator hose. This is due to being horizontal in the water. They are taught to use it from the beginning. Use of the pull dump on the inflator is discussed and discouraged except in cases of emergency. Proper use of the lower dumps actually gives more control and teaches them to finesse the release of air. Rather than just get rid of large quantities of it all at once.
I am horizontal 95% of the time. My shoulder dump is high on the BCD. I use the shoulder dump activated by a pull on my inflator hose almost all the time. It requires no adjustment of trim or shifting of body position. It is easy for me to release small or large amounts of air as is needed. Just like it is easy to put a little or more air in the BCD as needed.
Both of my computers are wrist mount. The pull dump also avoids constantly pissing them off by raising the arm.
I have found sometimes when renting a BCD, which is not often, that I have to adjust my style slightly in that i need to tilt up a few degrees when pull dumping.
Thanks to everyone for your posts. This has clarified a lot of things for me. I don't even recall being told to pull on my inflator hose to dump, but it was a while ago, so maybe I've just forgotten. I now have some specific things to practice on upcoming dives.
Personally I prefer to empty my bladder before donning my wetsuit / drysuit and as for dumping ….
On a more serious note though, before I moved to a BPW my BCD's usually had a separate shoulder dump on the right hand side as well as but dump IIRC also on the right hand side, I usually used either of these during the dive to trip etc and only the main inflator / dump valve on initial descent.
With my back inflate and BPW there is only the one dump valve on the bottom left hand side, and after 3+ years I am very much accustomed to using this valve consistently to adjust my trim during the dive.
As TS&M mentioned pulling on the main inflator hose may possibly cause this to become dis-attached, something I was informed about way back by an instructor when I bought my first BCD, prior to that I had never used a BCD.
It sounds like people are trying to invent the meaning of a lot of different words, and it sounds confusion to me.
However, it is my understanding that all the valves which are actuated by pulling on a string (or a wire located within the inflator hose) are held shut with a SPRING. The spring is selected to provide a maximum force (and therefore) pressure on the seating surface. Once the internal pressure exceeds that applied by this spring, the valve will release air without any mechanical input (i.e., pulling on a sting). So are not all dump valves also OPV Over Pressure-Release Valves?
I'm confused by some of the terminology people are using.
Thanks to everyone for your posts. This has clarified a lot of things for me. I don't even recall being told to pull on my inflator hose to dump, but it was a while ago, so maybe I've just forgotten. I now have some specific things to practice on upcoming dives.
Before you go pull on your inflator hose and rip it off make sure it has the cable in it for this type of activation not all BC's have this function! If it were me I would take a good look at your BC's bladder and where the dump valves are to give you a good idea were air can get trapped the air is going to migrate to the highest point and that would be the valve to use. You may not always be horizontal say your taking pictures on a wall vertical may be the choice so the air in the bladder will be at your shoulders so the dump on your butt won't do anything but let water in. The valves are not very high tech just disc covering a hole with a string attached there not a needle valve pretty much open or closed and how much air is released depends on how long you hold it open and if you hold it open to water goes in so if you have water in you BC at then end of a dive you're holding the dump open to long. My opinion is to work on your wieghting and if you get that dialed you won't have much need for adding or subtracting air.
I have found confusion springs from people not properly identifying the parts they are discussing. If I'm talking about one part and somebody else thinks I'm describing some other part confusion reins.
However, it is my understanding that all the valves which are actuated by pulling on a string (or a wire located within the inflator hose) are held shut with a SPRING. The spring is selected to provide a maximum force (and therefore) pressure on the seating surface. Once the internal pressure exceeds that applied by this spring, the valve will release air without any mechanical input (i.e., pulling on a sting). So are not all dump valves also OPV Over Pressure-Release Valves?
Over Pressure Valves feature compression spring acting to hold a valve poppet *against* rising gas pressure, when the force on the poppet exceeds the preload force of the spring the gas moves the poppet off it's seat.
This is not the case in a cable actuated "Rapid Exhaust" or "Pull Dump" or "Shoulder Dump" typically found on the connection between the corrugated hose and bladder on many recreational BC's
These Rapid Exhaust valves feature a spring which acts to hold the valve closed in conjunction with the gas pressure in the BC, rising pressure acts to hold these valves ever more tightly closed.
This is also the case with the Oral inflate / Manual dump button on most power inflators, the higher the gas pressure the greater the force holding the valve closed.
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.
