United States Patent [i9] [ii] Patent Number: 4,917,575
Miller, Jr. et al. [45] Date of Patent: Apr. 17, 1990
[21] Appl. No.: 261,056
[22] Filed: Oct. 27, 1988
Related U.S. Application Data
[63] Continuation of Ser. No. 859,175, May 2, 1986, abandoned.
[51] Int. Q.4 F04B 19/24
[52] U.S. CI 417/52; 210/191.2;
210/101; 417/209; 417/379
[58] Field of Search 417/379, 395, 52, 207,
417/208, 209; 210/198.2, 101; 222/146.5, 146.2
[56] References Cited
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FOREIGN PATENT DOCUMENTS
115159 8/1984 European Pat. Off. 417/52
1300401 12/1972 United Kingdom 417/52
OTHER PUBLICATIONS
Analytical Chemistry, "Thermal Pulse Time-of-Flight
Liquid Flow Meter", Thomas E. Miller, Jr., and Ham-
ish Small, vol. 54, No. 6, pp. 907-910.
American Laboratory, "Method For Precise Measure-
ment of Flow in LC", T. E. Miller, Jr., T. A. Chamber-
lin, and H. E. Tuinstra, Jan., 1983.
Primary Examiner—Leonard E. Smith
Attorney, Agent, or Firm—Burke M. Halldorson
[57] ABSTRACT
A liquid chromatographic method and apparatus is disclosed which employs an improved pump not requiring driven pistons or sliding seals. The pump comprises at least one length of tubing forming a chamber disposed between first and second check valves, controllable heating means to periodically heat liquid in said chamber effective to pump relatively low volumes of liquid from the chamber at relatively high pressures, means for measuring the pressure developed by the pump, and control means to increase and decrease the amount of heat imparted to the liquid to maintain the pump operation at a controlled pressure setpoint.
9 Claims, 7 Drawing Sheets
