Abstract: Between a characteristic a of a process chamber 21a having a large pressure loss and a characteristic b of a process chamber 21b having a small pressure loss, threshold value A (flow rate value Q3, pressure value P3) is set on the characteristic a. The threshold value A is set on a controller 9. When a rotation speed of a pump 3 is increased by an electric motor 8, the flow rate of a fluid flowing through pipelines 1, 2 and a flow path of a process chamber 21 increases. At the time, the flow rate of the fluid is measured by a flowmeter 4 and a pressure of the fluid is measured by a pressure switch 5. If the pressure reaches the pressure value P3 when the flow rate of the fluid reaches the flow rate value Q3, the pressure switch 5 operates. At the time, the controller 9 judges that the process chamber 21a having a large pressure loss is connected to the pipelines 1, 2.

Abstract: Between a characteristic a of a process chamber 21a having a large pressure loss and a characteristic b of a process chamber 21b having a small pressure loss, threshold value A (flow rate value Q3, pressure value P3) is set on the characteristic a. The threshold value A is set on a controller 9. When a rotation speed of a pump 3 is increased by an electric motor 8, the flow rate of a fluid flowing through pipelines 1, 2 and a flow path of a process chamber 21 increases. At the time, the flow rate of the fluid is measured by a flowmeter 4 and a pressure of the fluid is measured by a pressure switch 5. If the pressure reaches the pressure value P3 when the flow rate of the fluid reaches the flow rate value Q3, the pressure switch 5 operates. At the time, the controller 9 judges that the process chamber 21a having a large pressure loss is connected to the pipelines 1, 2.

Abstract: A swellable oil-absorbent agent formed of a cross-linked polymer (P) obtained by polymerizing a monomer component comprising 90 to 99.999% by weight of a monomer having as a main moiety thereof an alkyl (meth)acrylate the alkyl group of which has 10 to 16 carbon atoms and possessing one polymerizable unsaturated group in the molecular unit thereof and 0.001 to 10% by weight of a cross-linkable monomer possessing at least two polymerizable unsaturated groups in the molecular unit thereof (providing that the total of the amount of the polymerizable monomer and that of the cross-linkable monomer is 100% by weight).

Abstract: A swellable oil-absorbent agent formed of cross-linked polymer (P) obtained by polymerizing a monomer component comprising 90 to 99.999% by weight of a monomer having as a main moiety thereof an alkyl (meth)acrylate the alkyl group of which has 10 to 16 carbon atoms and possessing one polymerizable unsaturated group in the molecular unit thereof and 0.001 to 10% by weight of a cross-linkable monomer possessing at least two polymerizable unsaturated groups in the molecular unit thereof (providing that the total of the amount of the polymerizable monomer and that of the cross-linkable monomer is 100% by weight).

Abstract: A flotation collector is formed on a copolymer comprising (A) 2 to 95 mol % of a structural unit represented by the general formula I: ##STR1## wherein R.sup.1 is H or methyl, Y is --O-- or --NH--, A is C.sub.1-4 alkylene, C.sub.2-4 hydroxyalkylene, or phenylene, and Z is ##STR2## wherein R.sup.2, R.sup.3, and R.sup.4 are independently H, C.sub.1-12 alkyl or C.sub.7-10 aralkyl and X.sup..crclbar. is anion pair, (B) 5 to 98 mol % of a structural unit represented by the general formula II: ##STR3## wherein R.sup.5 is H or methyl and W is C.sub.6-8 aryl, ##STR4## wherein n is 2 to 4 and m is 0 to 20, ##STR5## wherein R.sup.6 is C.sub.1-18 alkyl, C.sub.5-8 cycloalkyl, C.sub.7-10 aralkyl, or C.sub.6-18 aryl, and (C) 0 to 50 mol % of other structural unit. A method for the treatment of an inorganic substance-containing water system by the use of the flotation collector.