JPS6245982A - Fluid pump equipped with temperature adjustor which keeps constant mass flow-rate - Google Patents

Abstract

PURPOSE:To obtain the captioned pump which always keeps a constant mass flow-rate by keeping each temperature of the inflow fluid and a chamber always constant. CONSTITUTION:Solvent is introduced into a head 3 through a suction pipe 6 form a bottle 1 charged with fluid. The intermediate part of the suction pipe 6 is constituted of a thermal equillibrium coil 2, and the periphery of the thermal equillibrium coil 2 is enclosed by an aluminium block 4. With such constitution, the temperature of the solvent becomes constant during passing through the thermal equillibrium coil 2, and the mass flow-rate can be kept always constant.

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention Industrial Application Field The present invention relates to a fluid pump mainly used as a liquid delivery pump for chromatography, and in particular maintains the inflowing fluid and the pump chamber at a constant temperature to control the mass flow rate of the fluid. This relates to a fluid pump with a temperature control device that maintains a constant temperature. Conventional technology A reciprocating piston type is generally used as a liquid pump for chromatography such as HPLC and SFC (supercritical fluid chromatography).

This type of fluid pump has a chamber that communicates with an inlet passage equipped with a check valve that allows only the inflow of fluid and an outlet passage equipped with a check valve that allows only the outflow of fluid, and a piston inside the chamber. The fluid is sucked and discharged by reciprocating.

The discharge amount per unit time of this type of pump is expressed as follows: Q = -vc-N where K is the efficiency, Vo is the volume change due to the movement of the piston, and N is the unit time. Number of piston strokes per hit.

Is the above discharge amount yJ? It varies depending on the structure of the glaze, the efficiency of the check valve, the compressibility of the fluid, and the amount of back pressure, but in short, the conventional glaze fluid y? The pump delivers a constant volume of fluid per unit time. Changes in efficiency that cause temporal fluctuations can be fairly well corrected by monitoring back pressure and the like and increasing or decreasing the number of strokes per unit time by a predetermined amount.

Problems to be Solved by the Invention However, in the case of organic solvents used in liquid chromatography, for example, methyl alcohol, the volume expansion per temperature IC is as high as 0.12%, and the volumetric flow rate of the pump is constant. Also, the mass flow rate is highly dependent on temperature. The influence of this temperature on the mass flow rate is shown in the graph of Figure 1.0 In the figure, the horizontal axis is the temperature (C)9 The dotted line vertical axis is the volumetric flow rate (cm mlmtn) eThe solid line vertical axis is the mass flow rate (f/m
in) and a volumetric flow rate of 0.4 m4/mln (diamond).

1, OmL/min (triangle), 5.0mL/
The mass flow rate (solid line) is shown when min (square) and 9,9 m7m1n (circle) (broken line).

Currently, the casting precision required in HPLC is 1 inch or more, and in particular GPC (y
0.1 for permeability chromatography)
A value of % is requested. Conventionally, in order to obtain good reproducibility of retention time, the column section has been kept at a constant temperature, and this has been effective to some extent. However, as mentioned above, the delivery flow rate of conventional pumps is controlled only by the volumetric flow rate, so even if the volumetric flow rate is constant due to changes in the solvent temperature due to changes in room temperature, temperature increases in the Chesono 9 due to mechanical friction, etc. , the mass flow rate varies greatly. As a result, even if the temperature of the column section is kept constant, the mass flow rate of the solvent flowing through the column changes, making it impossible to keep the retention time of sample components constant.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to improve upon the above points and provide a fluid pump which maintains constant mass flow rate by maintaining constant fluid (solvent) temperature and constant temperature.

In order to achieve the above object, the fluid pump according to the present invention includes chambers in the head that communicate with an inflow path that only allows inflow and an outflow path that allows only outflow, and a piston that reciprocates within the chambers. A fluid pump that sucks and discharges fluid by means of a fluid pump is characterized in that it includes means for maintaining the fluid flowing into the pump and the ponzo chamber at a constant temperature.

Preferably, the means for maintaining the temperature at a constant temperature includes a thermal balance coil through which fluid is passed, an aluminum block connected to the head, and a means for maintaining the temperature of the aluminum block at a constant temperature, such as a circulation constant temperature bath.

EXAMPLE Hereinafter, an example of the present invention will be described in detail with reference to FIG.

FIG. 2 is a diagram schematically showing the configuration of a fluid pump according to the present invention. In the figure, 3 is the head of the pump, and the head 3 has an inlet member 7 for attaching the suction pipe 6 to the head, and a discharge pipe 8 to the head. An outlet member 9 is provided for attachment to.

The internal structure of the head 3 is well known and is not particularly illustrated, but to briefly explain, the head 3 includes an inflow path that communicates with a suction pipe 6 and a discharge pipe 8 via a chamber, an inlet member 7, and an outlet member 9. , an outflow path is provided, and the chamber is open on one side (the right side in the figure). Since the inflow path is provided with a check valve that only allows inflow, and the outflow path is provided with a reverse valve that allows only outflow, fluid flows in only one direction. A piston is inserted into the chamber via a liquid-tight seal, and as the piston is reciprocated in the left-right direction in the figure by the piston drive device 10, fluid is sequentially drawn into the chamber and discharged from there.

Although the fluid pump described above can discharge a constant volumetric flow rate per unit time, the mass flow rate changes with the above-mentioned changes in the temperature of the particular fluid and the chamber 4. The mass flow rate is kept constant by providing means for keeping the temperature constant.

A preferred embodiment of the above means for keeping the temperature constant will now be described. In Figure 2, 1 is a tank containing a fluid, and when applied to chromatography, an organic solvent such as methyl alcohol is used as the fluid. The solvent is led from the tank 1 to the head 3 through a suction tube 6, and as shown in the figure, the suction tube 6 has a thermal balance coil 2 in its middle section. Since the ambient temperature surrounding the thermal equilibrium coil 2 is kept constant by the aluminum block 4 described later, the solvent is kept at a constant temperature while passing through the thermal equilibrium coil 2, and is not affected by changes in the ambient temperature.

Further, in the present invention, the head 3 of the fluid pump is connected to the aluminum block 4 so as to be able to conduct heat, and the temperature of the aluminum block 4 is controlled by the heat medium sent from the circulating constant temperature bath 5. Therefore, the chamber of the head 3 circle is maintained at a constant temperature and is not affected by temperature changes due to mechanical friction. Further, as described above, the aluminum block 4 also plays the role of keeping the temperature of the surrounding area including the thermal balance coil 2 constant.

In the illustrated embodiment, the temperature is controlled using a circulating constant temperature bath, but the temperature control method is not limited to this, and similar effects can be obtained by other methods such as using a Peltier resistor.

Effects of the Invention As described above, according to the present invention, by keeping the temperature of the inflow fluid (solvent) and the chamber constant, a fluid can be obtained that keeps the mass flow constant at all times. If applied, it is possible to prevent the holding time of sample components from changing due to changes in ambient temperature box or chamber temperature, and it is particularly effective in GPC etc. where high flow rate precision is required.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the effect of temperature change on mass flow rate, and FIG. 2 is a schematic diagram of a fluid pump according to the present invention. 1... Fluid (solvent) is Torr, 2... Thermal equilibrium coil,
3...Head, 4...Aluminum block, 5...Circulation thermostat, 6...Suction pipe, 8...Discharge pipe, 10...
・Guiston drive device. Applicant: JASCO Corporation Representative: Yuki Maruyama 1 Figure

Claims (2)

[Claims] (1) In a fluid pump that has a chamber in the head that communicates with an inflow path that allows only inflow and an outflow path that allows only outflow, and sucks and discharges fluid by reciprocating a piston within the chamber, inflow into the pump 1. A fluid pump with a temperature control device that maintains a constant mass flow rate, characterized in that the fluid pump is equipped with a means for maintaining a fluid and a pump chamber at a constant temperature. (2) The means for maintaining the temperature at a constant temperature includes a heat balance coil through which a fluid passes, an aluminum block connected to the head, and a means such as a circulating constant temperature bath for maintaining the temperature of the aluminum block at a constant level. Characteristic Claim No. 1
) A fluid pump with a temperature controller that maintains a constant mass flow rate.