What is claimed is:
1. A pump comprising:
a pump casing having an axis and comprising a cover having a face surface and a body positioned about the axis, with an arcuate channel defined in the face surface of the cover and extending at least partially circumferentially about the axis;
an inlet opening extending through the cover and coupled to the arcuate channel; and
an impeller positioned between the face surface of the cover and the body,
wherein the arcuate channel has a first section and a second section, with the first section extending from the inlet opening and being continually sloped relative to the face surface of the cover, said first section having a length of about 40 to about 90 degrees, as measured circumferentially on the face surface of the cover about the axis, said first section including an inlet ramp, a main ramp, and a secondary ramp, with the secondary ramp being positioned between the main ramp and the inlet ramp, and the inlet ramp being positioned adjacent the inlet opening, wherein each ramp has a depth and a slope, with the depth of the inlet ramp being greater than the depth of the secondary ramp, and the depth of the secondary ramp being greater than the depth of the main ramp, and the slope of each ramp is different from the slope of the other ramps.
2. The pump of claim 1, wherein the secondary ramp has a slope of less than or equal to about 30 degrees relative to the face surface of the cover
3. The pump of claim 1, wherein the main ramp has a slope of less than or equal to about 15 degrees relative to the face surface of the cover.
4. The pump of claim 1, wherein the inlet ramp comprises about 10% of the first section, the secondary ramp comprises about 30% of the first section, and the main ramp comprises about 60% of the first section.
5. The pump of claim 1, wherein the secondary ramp has a length that is about half the length of the main ramp.
6. The pump of claim 1, wherein the secondary ramp has a depth of about 4 mm to about 8 mm where it meets the inlet ramp, and the main ramp has a depth of about 2 mm to about 6 mm where it meets the secondary ramp.
7. The pump of claim 1, wherein the depth of inlet ramp varies, the depth of the secondary ramp varies, and the depth of the main ramp varies, the slope of the main ramp is generally constant, and the slope of the secondary ramp is generally constant.
8. The pump of claim 1, wherein the channel has an at least partially arcuate cross-section.
9. The pump of claim 1, wherein the impeller includes an inner disk and a plurality of vanes extending outwardly from an outer periphery of the inner disk, with the vanes each having an end and a root, and the channel has a width substantially equal to the distance between the vane end and the vane root.
10. The pump of claim 1, further comprising a vent purge hole positioned in the channel and extending through the cover.
11. A cover for a pump casing comprising:
a disc-shaped member having a longitudinal axis and a face surface, with an arcuate channel defined in and extending around the face surface; and
an inlet opening extending through the member and coupled to the channel,
wherein the channel has a first section and a second section, with the first section extending from the inlet opening and being continually sloped relative to the face surface of the member, said first section having a length of about 40 to about 90 degrees, as measured circumferentially on the face surface of the member about the axis, said first section including an inlet ramp, a main ramp, and a secondary ramp, with the secondary ramp being positioned between the main ramp and the inlet ramp, and the inlet ramp being positioned adjacent the inlet opening, wherein each ramp has a depth and a slope, with the depth of the inlet ramp being greater than the depth of the secondary ramp, and the depth of the secondary ramp being greater than the depth of the main ramp, and the slope of each ramp is different from the slope of the other ramps.
12. The cover of claim 11, wherein the secondary ramp has a slope of less than or equal to about 30 degrees relative to the face surface of the member.
13. The cover of claim 11, wherein the main ramp has a slope of less than or equal to about 15 degrees relative to the face surface of the member.
14. The cover of claim 11, wherein the depth of inlet ramp varies, the depth of the secondary ramp varies, and the depth of the main ramp varies, the slope of the main ramp is generally constant, and the slope of the secondary ramp is generally constant.
15. The cover of claim 11, wherein the inlet ramp comprises about 10% of the first section, the secondary ramp comprises about 30% of the first section, and the main ramp comprises about 60% of the first section.
16. The cover of claim 11, wherein the secondary ramp has a length that is about half the length of the main ramp.
17. The cover of claim 11, wherein the secondary ramp has a depth of about 4 mm to about 8 mm where it meets the inlet ramp, and the main ramp has a depth of about 2 mm to about 6 mm where it meets the secondary ramp.
18. The cover of claim 11, wherein the channel has an at least partially arcuate cross-section.
19. The cover of claim 18, wherein the channel has flat side walls that are perpendicular to the face surface of the member, and an arcuate bottom wall.
20. The cover of claim 18, wherein the cross-section of the channel is at least partially semi-circular.
21. The cover of claim 11, further comprising a vent purge hole positioned in the channel and extending through the member.
22. The cover of claim 21, wherein the vent purge hole is positioned at about 90 to 180 degrees from the inlet opening, when measured circumferentially about the longitudinal axis.
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 producing a compound of the formula (1) by separating its epimers contained therein:
which comprises subjecting a solution containing an alkyl (3R,5S)-7-2-cyclopropyl-4-(4-fluorophenyl)quinolin-3-yl-3,5-dihydroxy-6-heptenoate of the formula (1) (wherein R is a C1-4 alkyl group) to liquid chromatography treatment using uncoated silica gel as the packing material.
2. The method according to claim 1, wherein in the chromatography treatment, a mixed solvent comprising hexaneisopropyl alcohol is used as an eluent.
3. The method according to claim 2, wherein the ratio of hexaneisopropyl alcohol in the mixed solvent is from 991 to 5050 in a volume ratio.
4. The method according to any one of claims 1 to 3, wherein the uncoated silica gel as the packing material has an average particle diameter of from 0.1 \u03bcm to 10 mm and an average pore diameter of from 1 nm to 100 \u03bcm.
5. The method according to any one of claims 1 to 3, wherein the chromatography treatment is a treatment employing a simulated moving bed apparatus.
6. The method according to claim 5, wherein either component of the eluent is added to a distillate of the extract and raffinate recovered in the chromatography treatment, to adjust the compositional ratio of the distillate to the compositional ratio of the eluent before use, and the distillate so adjusted, is reused.
7. The method according to any one of claims 1 to 3, wherein R in the compound of the formula (1) is an ethyl group.