Patent ID: 8365779

Claim:
An apparatus comprising: a receptacle for storing liquid material; a first pipe for feeding feeder gas into said receptacle; a buffer tank coupled to the first pipe; a first shutoff valve provided in said first pipe upstream from the buffer tank; a pressure reduction valve provided in the first pipe downstream from the buffer tank; a first needle valve provided in said first pipe downstream from the pressure reduction valve; a second shutoff valve provided in said first pipe downstream from the needle valve; a first pressure detection means for detecting the pressure of feeder gas in said pipe between said first shutoff valve and said second shutoff valve, the first pressure detection means coupled to the buffer tank; a second pressure detection means for detecting the pressure of gas in said receptacle, the second pressure detection means coupled to said first pipe downstream from the second shutoff valve; a valve provided in the first pipe downstream of the second shutoff valve and upstream of the receptacle; and an arithmetic processing means for seeking by arithmetic calculation the liquid quantity of the liquid material in said receptacle on the basis of the detection results of said first pressure detection means and said second pressure detection means, in which said arithmetic processing means seeks by arithmetic calculation the liquid quantity of the liquid material in said receptacle on the basis of: V=V 1 −V 2×( PA 1 −PA 2)/( PB 2 −PB 1) wherein V: liquid quantity of liquid material in said receptacle, V 1 : volume of said receptacle, V 2 : volume of said pipe between said first shutoff valve and said second shutoff valve PA 1 : pressure of feeder gas in said pipe between said first shutoff valve and said second shutoff valve before it is fed into said receptacle, PA 2 : pressure of feeder gas in said pipe between said first shutoff valve and said second shutoff valve after it has been fed into said receptacle, PB 1 : pressure of feeder gas in said receptacle before the feeder gas is charged in said receptacle and PB 2 : pressure of feeder gas in said receptacle after the feeder gas has been charged in said receptacle.