Automatic dilution system for high-resolution particle size analysis

An automatic dilution system for providing an optimal value of dilution factor DF for a sample suspension containing particles mixed with a diluent, comprising:

• means for providing a continuous flow of said diluent into mixing means;
• means for injecting a continuous flow of said sample together with said diluent in said mixing means;
• sensor means for measuring a value of a particular characteristic related to particle concentration of said diluted sample leaving said mixing means, said sensor means having a particle coincidence concentration limit;
• controller means for determining from said value of said particular characteristic an optimal value of dilution factor DF needed to provide an optimal particle concentration in said diluted sample, said optimal particle concentration being the maximum particle concentration which does not exceed a desired percentage of said coincidence concentration limit of said sensor means, said controller means generating a control signal from said determined optimal value of dilution factor DF;
• and
• means responsive to said control signal for adjusting at least one of said flow of said sample and said flow of said diluent to provide said optimal value of dilution factor DF for said diluted sample in said mixing means, wherein said particular characteristic of said diluted sample comprises the initial rate of increase Rmax(0) of a quantity related to particle concentration in said diluted sample in said mixing means.

A method for automatically diluting a sample suspension containing particles with an optimal value of dilution factor DF, comprising:

• providing a continuous flow of diluent into mixing means;
• injecting a continuous flow of said sample into said mixing means;
• mixing said diluent and said sample in said mixing means to provide a diluted sample;
• measuring a value of a particular characteristic related to particle concentration of said diluted sample;
• determining from said value of said particular characteristic an optimal value of dilution factor DF to provide an optimal particle concentration in said diluted sample;
• generating a control signal from said determined optimal value of dilution factor DF;
• and
• in response to said control signal adjusting said flow of said sample to provide said optimal value of dilution factor DF in said mixing means.

An automatic diluting system for controlling the value of dilution factor DF for a concentrated sample suspension containing particles mixed with a diluent, comprising:

• means for providing a flow of diluent into mixing means;
• means for injecting a flow of a concentrated sample suspension into said mixing means to dilute said sample;
• sensor means for determining the particle count rate of said diluted sample leaving said mixing means;
• means for deriving a control signal from said count rate;
• and
• means responsive to said control signal for adjusting one of said flow of concentrated sample suspension and said flow of diluent to adjust said dilution factor DF, said flows of diluent and sample suspension into said mixing means being continuous.

An automatic dilution system for controlling the dilution factor DF for a concentrated sample suspension containing particles mixed with a diluent, comprising,

• means providing a continuous flow of diluent into mixing means;
• sample delivery means for delivering a flow of said concentrated sample suspension at a continuous flow rate FS into said mixing means to dilute said sample;
• sensor means for determining the particle concentration per unit volume of said diluted sample leaving said mixing means;
• and
• means for deriving a control signal from said particle concentration per unit volume;
• said sample delivery means being responsive to said control signal for adjusting said flow rate FS of said concentrated sample suspension to adjust said dilution factor DF.

A method for automatically diluting a sample suspension, comprising:

• feeding a diluent fluid into mixing means;
• initially injecting a sample suspension to be diluted into a capture loop;
• and
• then feeding a diluent fluid at a controlled, adjustable flow rate into one end of said capture loop to force said sample suspension undiluted from said the other end of said capture loop into said mixing means.

A method for automatically diluting a sample suspension, comprising:

• prediluting said sample suspension in first mixing means with a diluent fluid to provide a prediluted sample suspension;
• continuously adding diluent fluid at a controlled, adjustable rate to said mixing means to force said prediluted sample out of said first mixing means into second mixing means;
• and
• further diluting said prediluted sample in said second mixing means by continuously feeding a diluent at a controlled, adjustable flow rate into said second mixing means.

A method for automatically diluting a sample suspension having a particle size distribution characteristic with tail portions at its upper and lower ends, comprising:

• setting the starting threshold diameter to limit examination of said sample suspension to a range of particle sizes in one of said tail portions;
• measuring the particle concentration in said range of particle sizes in said one of said tail portions;
• and
• adjusting the dilution factor of said sample in response to said measurement.