1. A vent control valve for a fuel tank, comprising:
a cylindrical housing extending vertically, and configured to be attached to an upper wall of a fuel tank, the housing having an open lower end and a closed upper end defining a port communicating an interior of the housing with an external part of the fuel tank;
a float assembly received in the housing and guided for a vertical movement therein, defining a prescribed gap between an outer profile of the float assembly and an inner circumferential wall of the housing; and
a valve member provided in an upper part of the float assembly to close the port of the cylindrical housing when the float assembly has floated to a prescribed height;
wherein the cylindrical housing is provided with a communication hole passed across a wall of the housing, an opening of the communication hole facing an interior of the housing being directly exposed to an interior of the housing when the float assembly is in a low position and overlapping with a peripheral wall of the float assembly when the float assembly is in a high position.
2. The vent control valve according to claim 1, wherein a plurality of vertically extending ribs are provided on an inner circumferential surface of the housing to guide the float assembly for a vertical movement.
3. The vent control valve according to claim 2, wherein at least one of the ribs is provided with a laterally enlarged portion, the communication hole being passed across a thickness of the lateral enlarged portion.
4. The vent control valve according to claim 3, wherein the float assembly comprises a lower float and an upper float connected to each other so as to permit a small displacement between them, and the valve member is provided on the upper end of the upper float.
5. The vent control valve according to claim 4, wherein the float assembly further comprises a middle float which is connected to the lower float so as to permit a small displacement between them, and the valve member comprise a rubber seal having a central hole passed vertically across the rubber seal, the rubber seal including an annular upper part configured to cooperate with a peripheral part of the port and a lower lip seal configured to close the central hole in cooperation with an upper surface of the middle float.
6. The vent control valve according to claim 5, wherein an upper part of the lower float is formed with a reduced diameter portion and a radial flange formed at an upper end of the reduced diameter portion, and the upper float is provided with an upper horizontal wall and a peripheral wall depending from a peripheral part of the upper horizontal wall, a lower edge of the peripheral wall being provided with an engagement portion engaging the radial flange of the lower float.
7. The vent control valve according to claim 6, wherein the upper horizontal wall of the upper float is provided with a central opening having the rubber seal fitted therein.
8. The vent control valve according to claim 7, wherein the middle float comprises an upper horizontal wall and a plurality of legs depending from the upper horizontal wall and received in openings formed in the radial flange of the lower float so as to guide a vertical movement of the middle float relative to the lower float.
9. The vent control valve according to claim 4, further comprising a compression spring interposed between the lower float and a shoulder piece extending radially inwardly from an inner circumferential surface of the housing.
10. The vent control valve according to claim 1, wherein the cylindrical housing is provided with two or more communication holes passed across a wall of the housing at a regular angular interval.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method for measuring a concentration of protein, comprising the steps of:
(a) measuring intensities of at least a transmitted light or a scattered light of a solution to be detected before and after mixing therein one reagent selected from the group consisting of tannin, tannic acid and m-galloyl gallic acid, and
(b) determining a concentration of protein in said solution to be detected based on said intensities.
2. The method for measuring a concentration of protein in accordance with claim 1, comprising a step of:
(a) regulating a pH of a solution to be detected to 1.5 to 5.8 after mixing therein said reagent in said step (a).
3. The method for measuring a concentration of protein in accordance with claim 2,
wherein the pH of the solution to be detected is regulated by adding a pH controlling agent selected from the group consisting of potassium hydrogen phthalate, acetic acid, citric acid and ascorbic acid in said solution to be detected in said step (a).
4. The method for measuring a concentration of protein in accordance with claim 1,
wherein a concentration of a reagent in a solution to be detected after mixing therein said reagent is in the range of 5103 to 5 gdl in said step (a).
5. The method for measuring a concentration of protein in accordance with claim 1,
wherein the protein concentration in said solution to be detected is determined based on the intensities of said transmitted light and said scattered light in said step (b).
6. The method for measuring a concentration of protein in accordance with claim 5,
wherein a concentration of protein in a solution to be detected in a low concentration range is determined from the intensity of said scattered light, and that of a solution to be detected in a high concentration range is determined from the intensity of said transmitted light.
7. The method for measuring a concentration of protein in accordance with claim 5, comprising a step of:
(c) detecting the presence or absence of an erroneous measurement due to a suspending particle such as a bubble in said solution to be detected by comparing the intensity of said transmitted light with that of said scattered light.
8. A method for measuring a concentration of a solution, comprising the steps of:
(i) measuring intensities of at least a transmitted light or a scattered light of a solution to be detected before and after mixing therein one reagent selected from the group consisting of tannin, tannic acid and m-galloyl gallic acid, and
(ii) measuring an angle of rotation of said solution to be detected before mixing therein said reagent,
(iii) determining a concentration of protein in said solution to be detected based on the intensities of at least said transmitted light or said scattered light, and
(iv) determining a concentration of any optical active substance in said solution to be detected other than said protein from said concentration of protein and said angle of rotation.
9. The method for measuring a concentration of a solution in accordance with claim 8, comprising a step of:
(i) regulating a pH of said solution to be detected to 1.5 to 5.8 after mixing therein said reagent in said step (i).
10. The method for measuring a concentration of a solution in accordance with claim 10,
wherein the pH of the solution to be detected is regulated by mixing a pH controlling agent selected from the group consisting of potassium hydrogen phthalate, acetic acid, citric acid and ascorbic acid in said solution to be detected.
11. The method for measuring a concentration of a solution in accordance with claim 9,
wherein a concentration of a reagent in a solution to be detected after mixing therein said reagent is in the range of 5103 to 5 gdl in said step (i).
12. A reagent for measuring a concentration of protein to be used in a method for measuring a concentration of protein in which a reagent is mixed in a solution to be detected and a concentration of protein is determined from the resulting turbidity,
wherein said reagent contains at least one selected from the group consisting of tannin, tannic acid and m-galloyl gallic acid.
13. The reagent for measuring a concentration of protein in accordance with claim 12,
wherein the pH thereof is regulated to the range of 1.5 to 5.8.
14. The reagent for measuring a concentration of protein in accordance with claim 12,
wherein said reagent contains one acid selected from the group consisting of potassium hydrogen phthalate, acetic acid, citric acid and ascorbic acid as a pH controlling agent.
15. The reagent for measuring a concentration of protein in accordance with claim 12,
wherein said reagent is an aqueous solution dissolved in water.
16. The reagent for measuring a concentration of protein in accordance with claim 15,
wherein the concentration of said reagent in said aqueous solution is 250 gdl or lower.
17. The reagent for measuring a concentration of protein in accordance with claim 13,
wherein the concentration of said pH controlling agent is at the highest possible level as long as said ph controlling agent does not deposit in a temperature range operable for said reagent.