Pipes and tubular conduits – With pressure compensators – Variable capacity chambers
Patent
1987-01-13
1989-01-03
Cuchlinski, Jr., William A.
Pipes and tubular conduits
With pressure compensators
Variable capacity chambers
2101982, F16L 5504
Patent
active
047949546
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an apparatus for liquid chromatograph, particularly to an apparatus and a method for the prevention of pulsating flow in the liquid chromatograph, wherein pulsations in the flow of liquid being transferred are eliminated.
BACKGROUND ART
In the most popular method of transferring liquid in the liquid chromatography, a plunger type pump is used and the transfer is performed by a reciprocating motion of the plunger. This generates a pulsating flow of the liquid being transferred, in accordance with the reciprocal motion of the plunger. In a conventional control method for eliminating the pulsations in the flow, a plurality of plungers are used in such a way that they react with each other to eliminate the pulsations. Nevertheless, this method has not achieved a complete elimination of pulsations in the flow.
Alternative methods of inserting an apparatus for the prevention of pulsating flow are known, in which the means used in the liquid transfer system is a flat pipe, a bellows, a spring, a combination of a bellows and a spring, or a combination of a diaphragm and a compressible liquid. Among the above-mentioned methods, that utilizing the change of volume of a flat pipe is effective only when the flat pipe is extremely long, which leads to the presence of a large dead volume causing extreme inconvenience when replacing the liquid. Further, a method using a bellows is effective only under a pressure of up to about 50 bar, and also is inconvenient when replacing the liquid due to a complicated configuration of the bellows. A method utilizing the elasticity of a spring is not effective in the low pressure range, and is inconvenient in that the rigidity and elasticity of the spring must be adjusted in accordance with changes in the liquid pressure. Further, a method using the combination of a bellows and a spring is effective to a certain extent from a low to a high pressure, but is still inconvenient in that the rigidity of spring must be adjusted.
Further, in an apparatus for the prevention of pulsating flow, such as disclosed in Japanese Unexamined Patent Publication No. 57-160060, in which one side of a flat flow path chamber is partitioned by a diaphragm and a sealed compression chamber enclosing a compressible liquid is provided facing the diaphragm, the volume of the compression chamber must be satisfactorily large in order to realize an effective prevention of pulsating flow, which necessitates a significantly large diaphragm, and as a result, makes it impossible to obtain a compact apparatus having a good performance for the prevention of pulsating flow in the liquid chromatograph.
In Japanese Unexamined Patent Publication No. 57-160060, a compression liquid chamber, which is used to prevent pulsating flow of a liquid being transferred at a reciprocation cycle of about 1 sec by a piston pump having a maximum capacity of 100 .mu.l, is composed of a cylindrical portion having an aperture of 80 mm and a height of 88 mm and a conical portion having a depth of 10 mm and located below the cylindrical portion.
DISCLOSURE OF THE INVENTION
The present invention is intended to solve the conventional problems as mentioned above, and provides an apparatus for the prevention of pulsating flow in the liquid chromatograph, which has an excellent performance for the prevention of pulsating flow, a small dead volume, and an excellent operability, evenly throughout the whole region of from 5 to 400 bar of ordinary use for the liquid chromatograph.
An apparatus for the prevention of pulsating flow in the liquid chromatograph according to the present invention comprises a pressure vessel provided with a liquid transferring chamber partitioned by diaphragms on both flat sides thereof, and sealed compression chambers filled with a compressible substance and disposed facing said diaphragms.
If a compression chamber is provided on only one side of a liquid transferring chamber, only a single diaphragm will be used, and therefore, deformation of the diaphragm is doubled w
REFERENCES:
patent: 2883180 (1959-04-01), Moulton
patent: 4024061 (1977-05-01), Gatiss
patent: 4222414 (1980-09-01), Achener
patent: 4427029 (1984-01-01), Charney et al.
patent: 4552182 (1985-11-01), Graham
patent: 4587993 (1986-05-01), Hartl
patent: 4629562 (1986-12-01), Kercher
Ishida Norio
Tokieda Tsunemi
Tokuda Toshio
Cuchlinski Jr. William A.
Showa Denko Kabushiki Kaisha
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