After assembly, the regulator must be checked to ensure that its interior is tightly sealed.
In order to completely seal the inside of the regulator, first, you must use an O-ring of the correct size and material according to the design, second, there must be no cracks in the body or even the slightest damage to parts such as the diaphragm, and finally, you must check whether the seat is properly seated in the orifice.
Until now, to test water tightness, workers had used the method of blocking the hose connection of the second stage regulator with their hands and sucking a vacuum through their mouths.
At this time, the vacuum pressure sucked through the mouth must be large enough to be approximately 16KPa for the regulator to be attached to the mouth. Of course, you can immediately check if there are cracks in the body, damage to the diaphragm, or if a different size O-ring is used.
However, it is not easy to detect small leaks such as unstable O-ring seating due to oxidation of parts or small damage or fine cracks in the O-ring using this method.
Moreover, to set the cracking pressure after conducting a vacuum test in this way, the cracking pressure is set without checking whether the area connecting the differential pressure gauge and the second stage regulator is properly sealed.
In fact, in most cases, this connection is not sealed properly.
Since the cracking pressure is a small vacuum of less than 500 Pascal, if this area is not properly watertight, the repair person will not notice it and sets the cracking pressure by sucking air with the force he normally suctions while looking at the scale of the differential pressure gauge.
As a result, the cracking pressure set in this way cannot be said to be the correct setting because it is set as the cracking pressure by adding the amount of leakage at this connection point.
Depending on the cause, it can have different consequences during a dive. If the regulator has a leak inside, water may enter if more air is sucked in than usual, and if there is a leak at the connection, the diver may complain that breathing is more difficult than before.
Therefore, the watertightness test of the second stage regulator must be tested in a microvacuum of less than 800 Pascal.
SRSD can perform watertightness testing precisely using micro-vacuum pressure, replacing the watertightness testing method used in the past.
Whether the seat is properly seated in the orifice will be explained in the next topic.