Patent ID: 7279076

Claim:
A method for handling an easily polymerizable substance, comprising: feeding liquid containing an easily polymerizable substance from a decompressor, used to handle said liquid under reduced pressure, via a feed pipe, having an upstream end that opens in said decompressor, through one of a first strainer and a second strainer, with said first and second strainers being connected in parallel with one another to said feed pipe; measuring a difference between a first pressure in said feed pipe on an upstream side of said one of said first and second strainers and a second pressure in said feed pipe on a downstream side of said one of said first and second strainers; and based on the difference between said first and second pressures, as measured, (i) stopping the feeding of said liquid through said one of said first and second strainers, and (ii) initiating feeding of said liquid, via said feed pipe, through the other of said first and second strainers, wherein associated with the other of said first and second strainers is (i) a first valve on an upstream side of the other of said first and second strainers, (ii) a second valve on a downstream side of the other of said first and second strainers, and (iii) an exhaust device, wherein initiating feeding of said liquid through the other of said first and second strainers comprises feeding said liquid to a part between said first and second valves such that said exhaust device allows said liquid to expel air from said part between said first and second valves, wherein a pump is in a mid-section of said feed pipe, with said first and second strainers being on an upstream side of said pump, wherein associated with said one of said first and second strainers is (i) a third valve on an upstream side of said one of said first and second strainers, (ii) a fourth valve on a downstream side of said one of said first and second strainers, and (iii) another exhaust device, and wherein a branch pipe connects said part between said first and second valves and a part between said third and fourth valves with a part of said feed pipe on a downstream side of said pump, such that (i) feeding said liquid to said part between said first and second valves comprises feeding said liquid, via said branch pipe, to said part between said first and second valves, and (ii) said another exhaust device is for exhausting air from a part between said third and fourth valves in response to said liquid when introduced from said branch pipe to said part between said third and fourth valves and expelling air from said part between said third and fourth valves.