Abstract: A fuel vapor treatment apparatus includes a first canister purges fuel vapor into an intake passage of an engine through a purge passage, which communicates with a first detection passage having a throttle. A second canister is located on an opposite side of the purge passage with respect to the throttle, and communicates with the first detection passage. A gas flow generating unit generates gas flow by reducing pressure in a second detection passage communicating with the second canister. A pressure detecting unit detects pressure correlated with the throttle and the gas flow generating unit. An exhaust detecting unit detects exhaust of fuel vapor from the second canister to the second detection passage. A purge control unit controls purge of fuel vapor from the purge passage to the intake passage in accordance with detection results of the pressure detecting unit and the exhaust detecting unit.

Abstract: A fuel vapor treatment apparatus includes a first canister purges fuel vapor into an intake passage of an engine through a purge passage, which communicates with a first detection passage having a throttle. A second canister is located on an opposite side of the purge passage with respect to the throttle, and communicates with the first detection passage. A gas flow generating unit generates gas flow by reducing pressure in a second detection passage communicating with the second canister. A pressure detecting unit detects pressure correlated with the throttle and the gas flow generating unit. An exhaust detecting unit detects exhaust of fuel vapor from the second canister to the second detection passage. A purge control unit controls purge of fuel vapor from the purge passage to the intake passage in accordance with detection results of the pressure detecting unit and the exhaust detecting unit.

Abstract: A method is proposed for the preparation of porous calcium carbonate particles of which each of the particles is not an aggregate but has ink bottle-shaped pores each not communicating with the others. The method comprises: (a) blending particles of heavy calcium carbonate having a specific particle size distribution with from 0.1 to 0.3% by weight of a porosity-forming agent, e.g., sodium chloride; (b) calcining the powder blend at a temperature in the range from 800.degree. C. to 1000.degree. C. to decarbonate the calcium carbonate particles into particles of calcium oxide having pores developed therein; (c) slaking the particles of calcium oxide with steam to convert the calcium oxide particles into particles of calcium hydroxide; (d) drying the particles of calcium hydroxide at a temperature in the range from 100.degree. C. to 350.degree. C.; and (e) carbonating the dried particles of calcium hydroxide with carbon dioxide gas at a temperature in the range from 600.degree. C. to 750.degree.C.