portion 70 of spool member 38 from seal insert 72 thereby opening port 73 and permitting high velocity fluid stream 500 to pass therethrough and flow into nozzle cavity 88 and into low pressure cavity 101 as described above as fluid pressure within low pressure cavity 101 increases the opposing force acting upon diaphragm member 108 overcomes the biasing force of spring member 118 and drives diaphragm member 108 away from stem member 98 consequently valve spring 64 urges spool member 38 upward and again seats nose portion 70 into sealing engagement with seal insert 72 thereby closing port 73 fluid within low pressure cavity 101 may then exit through discharge channels 124 and outlet port 30 low pressure cavity 101 is particularly shaped to decrease vibration and improve efficiency as with the nozzle backpressure discussion above a similar principle holds true for diaphragm member 108 a certain amount of backpressure should be maintained under diaphragm member 108 this backpressure is the delivery pressure of gas pressure regulator 10 and is shown on a delivery pressure gauge the key to achieving the highest performance of gas pressure regulator 10 is to maximize the flowrate of high velocity stream 500 in this regard the high flowrate is capable of delivering a high throughput in response to increased downstream load i e a machine or work device the key to delivering this high throughput is to quickly and efficiently slow down high velocity stream 500 diffuse it and distribute it evenly through low pressure cavity.