Power inflator mechanisms and what to do in a malfunction situation
I found this post on a FaceBook group: “I don’t know how many of you have experienced such problem but today during my first deep dive in advance course I encountered malfunction of equipment. My power inflator got stuck in inflate position and I started having uncontrolled ascent . First I didn’t know how to control but was able to control quick ascent by pressing deflate same time. By time my dive instructor noticed and came for help and disconnected the law pressure hose from the power inflator and deflate the the BCD and then we continued diving for another 30 mins without any problem.”
I think it will be helpful to answer it here:
First, the emergency procedure for a BCDs inflator mechanisms should be taught during the Open Water Class, in the pool and as instructor “discretion” in open water.
Let’s review the basic configuration and how the power inflator works:
All Buoyancy Compensator are equipped with an inflator mechanisms, this can be used orally and mechanically. The conventional power-inflator consists in a body that contains one exhaust button and one inflation button.
The inflation button regularly are fitted with a poppet, a bushing and a spring. When the button is depressed, the air passes through the poppet, orifice/orings system permitting the air entering into the corrugated hose and then into the BC or wing/bladder. The air comes from the cylinder and it is reduced to a low pressure by design of the first stage regulator.
The oral inflator mechanisms is simple, a set of orings and a pin that is pushed to allow the air cross. When the button is depressed and the diver blows into the mouthpiece, the air enters. If is remains depressed without the diver blowing into it, the air will escape. This means that this button is also a deflator mechanisms, and it’s the main one.
Also the BCDs or wings can be released quickly trough a dump valve. Dump valves are activated by a simple pull string or lever.
The same dump valve usually is the over-expansion safety valve mechanisms. Many BCD’s have up to three different valves located in different places to allow to dump air in various positions.
When the regulator is turned on, the pressure coupling excess 135 psi, and the force pressure against the locking mechanisms on the coupling makes it more difficult to disconnect.
In a malfunction situation most divers find that they are already at the surface when they manage to disconnect the coupling. This occurs because this skill is majorly overlooked.
If you think about it, if the diver used a dump valve located anywhere in the BC less than which is located at the corrugated hose, the air must flow trough the BC bladder, increasing the diver’s buoyancy before the air vents back into the water.
The Jet dump valve address this issue, which is located at the end of the corrugated hose (more of this later).
The other quickly way to address this issue is depressed the exhaust valve of the power inflator first with one hand, putting the power inflator at a high point as possible; that way, the air will not go into the bladder, and will not affected the diver’s buoyancy; at the same time, with the other hand disconnect the coupling.
The diver position must be with head a little bit more high than the rest of the body. It is not necessary to adopt a complete vertical position.
The jet valve or plunger valve works with the same principle as the dump valves with only two moving parts and a seal. This are connected it with a cable to the power inflator and when it is pulled, the air will scape from between the plunger and the seal.
This mechanisms will not allow the air travel across the bladder to be dump into the water. And it is a highest point with relation to the rest of the body.
As we mentioned earlier, the plunger is located it at the end of the corrugated hose.
This should be practice regularly and must be taught in the open water course.