| 摘要 |
A pneumatically-operated gas demand apparatus coupled in interruptible fluid communication between a recipient and a first source of a pressurized first gas controls delivery of the first gas to the recipient as the recipient inhales and exhales and comprises a supply valve and a sensing valve. The supply valve has a first interior chamber divided by a flexible first diaphragm into a supply chamber region and a control chamber region. The supply chamber region is in interruptible fluid communication between the first source of the first gas and the recipient. The control chamber region is in continuous fluid communication with a second source of a pressurized second gas. The sensing valve has a second interior chamber divided by a flexible second diaphragm into a venting chamber region and a sensing chamber region. The venting chamber region is in interruptible fluid communication between the control chamber region and an ambient air environment. The sensing chamber region is in continuous fluid communication with the recipient. When the recipient inhales, the second diaphragm moves to a flow-causing position to cause the second gas to flow into the ambient air environment and causes the first diaphragm to move to a flow-supplying position thereby delivering the first gas to the recipient. When the recipient exhales, the second diaphragm moves to a flow-stopping position to prevent the second gas to flow into the ambient air environment and causes the first diaphragm to move to a flow-blocking position thereby preventing delivery of the first gas to the recipient. |
