Pilot valve operated demand regulator for a breathing apparatus

A pneumatically assisted demand valve for a scuba regulator second stage, said second stage having a body including an inlet port to which breathable gas is supplied from the regulator first stage, and a valve support structure within said body including a support ring and a tubular member ridigly connecting said ring to said body, said valve comprising:

• a flow control valve having a relatively stationary housing that is removably mounted within said support ring, said housing having an inlet chamber therein to which breathable gas is supplied via said inlet port and said tubular member, said inlet chamber having an open end forming a valve seat and a closed end, said flow control valve also having a relatively movable poppet situated for reciprocation within said inlet chamber and having a portion that cooperates with said valve seat to block or open a flow path for breathable gas from the regulator first stage past the inlet chamber open end to the mouthpiece, said poppet being biased toward the flow blocking position in which said portion closes said inlet chamber open end, said poppet having sealing means for preventing the flow of breathable gas from said regulator first stage to a space between said poppet and the closed end of said inlet chamber, and
• a pilot valve mounted within and carried by said poppet for controllably admitting input breathable gas through a channel within said poppet to said space between said poppet and said inlet chamber closed end so that the pressure of said admitted gas urges movement of said poppet against said bias toward the open flow position, said pilot valve comprising;
• a pilot valve seat formed as an integral part of said poppet,
• a closure within said poppet, and
• bias means comprising a spring carried completely within said poppet for biasing said closure against said pilot valve seat so as to block the flow of input breathable gas into said space via said channel, said closure being opened by movement away from said pilot valve seat in a direction the same as opening movement of said poppet, said spring urging said closure back toward said pilot valve seat during opening movement of said poppet.