Method and device for verification and/or calibration of a pressure sensor

Patent metadata

Field	Value
Publication number	US-9664585-B2
Application number	US-201314428424-A
Country	US
Kind code	B2
Filing date	Sep 13, 2013
Priority date	Oct 23, 2012
Publication date	May 30, 2017
Grant date	May 30, 2017

Abstract

A method for calibrating a pressure sensor includes connecting the pressure sensor to first and second fluid storage vessels; providing an initial fluid pressure at the pressure sensor and at the fluid storage vessels; and carrying out a pressure measurement of the initial fluid pressure at a time t 0 . The method then disconnects the second fluid storage vessel from the pressure sensor and the first fluid storage vessel; provides a first fluid pressure at the second fluid storage vessel; and carries out a pressure measurement of the first fluid pressure at a time t 1 . The method then connects the second fluid storage vessel with the pressure sensor and the first fluid storage vessel, so that a second fluid pressure between the initial and first fluid pressures is provided at the pressure sensor; and carries out a pressure measurement of the second fluid pressure at a time t 2 .

First claim

The invention claimed is:

1. A method for carrying out a verification and/or a calibration test on a pressure sensor ( 3 ), the method comprising the steps of:
fluidly connecting the pressure sensor ( 3 ) to a first fluid storage vessel ( 17 );
fluidly connecting the pressure sensor ( 3 ) to a second fluid storage vessel ( 21 );
providing an initial fluid pressure p 0 at the pressure sensor ( 3 ), the first fluid storage vessel ( 17 ) and the second fluid storage vessel ( 21 );
carrying out a pressure measurement of the initial fluid pressure p 0 at a time t 0 by means of the pressure sensor ( 3 );
fluidly disconnecting the second fluid storage vessel ( 21 ) from the pressure sensor ( 3 ) and the first fluid storage vessel ( 17 )
providing a first fluid pressure p 1 at the first fluid storage vessel ( 17 );
carrying out a pressure measurement of the first fluid pressure p 1 at a time t 1 by means of the pressure sensor ( 3 );
fluidly connecting the second fluid storage vessel ( 21 ) with the pressure sensor ( 3 ) and the first fluid storage vessel ( 17 ), so that a second fluid pressure p 2 is provided at the pressure sensor ( 3 ), wherein the second fluid pressure is between the initial fluid pressure p 0 and the first fluid pressure p 1 ;
carrying out a pressure measurement of the second fluid pressure p 2 at a time t 2 by means of the pressure sensor ( 3 ).

2. The method of claim 1 comprising the further step of:
determining the difference Δp 2 between the measured second fluid pressure p 2 and a predicted second fluid pressure <p 2 > predicted using formula
< p 2 >=( p 1 V 1 +p 0 V 2 )/( V 1 +V 2 ),

wherein V 1 is the volume of the first fluid storage vessel ( 17 ) and wherein V 2 is the volume of the second fluid storage vessel ( 21 ).

3. The method of claim 2 comprising the further step of:
determining whether the difference Δp 2 is within a predefined limit ε.

4. The method of claim 1 , wherein the initial fluid pressure p 0 is the atmospheric pressure.

5. The method of claim 1 , further comprising the steps of:
providing a third fluid storage vessel ( 37 ) being initially at the initial fluid pressure p 0 ;
fluidly connecting the pressure sensor ( 3 ), the first fluid storage vessel ( 17 ) and/or the second fluid storage vessel ( 21 ) to the third fluid storage vessel ( 37 ), so that a third fluid pressure p 3 is provided at the pressure sensor ( 3 ), wherein the third fluid pressure p 3 is between the initial fluid pressure p 0 and the second fluid pressure p 2 ;
carrying out a pressure measurement of the third fluid pressure p 3 at a time t 3 by means of the pressure sensor ( 3 ).

6. The method of claim 5 comprising the further step of:
determining the difference Δp 3 between the measured third fluid pressure p 3 and a predicted third fluid pressure <p 3 > predicted using formula
< p 3 >=( p 2 ( V 1 +V 2 )+ p 0 V 3 )/( V 1 +V 2 +V 3 ),

wherein V 3 is the volume of the third fluid storage vessel ( 37 ) and
optionally determining whether the difference Δp 3 is within a predefined limit ε.

7. The method of claim 5 , further comprising the steps of:
iteratively performing the following method steps subsequently for all natural numbers n being within the interval 4≦n≦N and N being a natural number of maximum iterations:
providing a n-th fluid storage vessel being initially at the initial fluid pressure p 0 ;
fluidly connecting the pressure sensor ( 3 ) and the first to n-th fluid storage vessel to the n-th fluid storage vessel, so that a n-th fluid pressure p n is provided at the pressure sensor ( 3 ), wherein the n-th fluid pressure p n is between the initial fluid pressure p 0 and the (n−1)-th fluid pressure p (n−1) ;
carrying out a pressure measurement of the n-th fluid pressure p n at a time t n by means of the pressure sensor ( 3 ).

8. The method of claim 1 , further comprising the steps of:
fluidly disconnecting the pressure sensor ( 3 ) and the first fluid storage vessel ( 17 ) from the second fluid storage vessel ( 21 );
providing again the initial fluid pressure p 0 at the pressure sensor ( 3 ) and the first fluid storage vessel ( 17 );
fluidly connecting the second fluid storage vessel ( 21 ) with the pressure sensor ( 3 ) and the first fluid storage vessel ( 17 ), so that a third fluid pressure p 3 is provided at the pressure sensor ( 3 ), wherein the third fluid pressure p 3 is between the initial fluid pressure p 0 and the second fluid pressure p 2 ;
carrying out a pressure measurement of the third fluid pressure p 3 at a time t 3 by means of the pressure sensor ( 3 ).

9. The method of claim 1 comprising the further step of:
computing a linear regression of the measured pressure values versus the predicted pressure values in order to determine a calibration function.

10. A test device ( 1 ) for automatically carrying out a calibration test on a pressure sensor ( 3 ), the test apparatus comprising:
a fluid line ( 11 ) which is fluidly connected to the pressure sensor ( 3 ) to be tested via a pressure sensor valve;
a first fluid connector ( 19 ) configured to fluidly connecting a first fluid storage vessel ( ) to the fluid line ( 11 );
a vessel valve ( 25 ) configured to fluidly connect or disconnect the second fluid connector ( 23 ) from the pressure sensor ( 3 );
a fluid outlet ( 9 ) configured to release fluid from the fluid line ( 11 ) via an outlet valve ( 15 );
a fluid inlet ( 7 ) configured to fluidly connecting a fluid source to the fluid line ( 11 ) via an inlet valve ( 13 );
a control unit ( 27 ) configured to perform automatically the following control steps:
closing the inlet valve ( 13 );
opening the vessel valve ( 25 ) to fluidly connect the pressure sensor ( 3 ) to the second fluid connector ( 23 );
opening the outlet valve ( 15 ) to provide atmosphere pressure at the pressure sensor ( 3 ), the first fluid connector ( 19 ) and the second fluid connector ( 19 );
performing a pressure measurement of the atmosphere pressure as the initial fluid pressure p 0 at a time to by means of the pressure sensor ( 3 );
closing the outlet valve ( 15 ) and the vessel valve ( 25 );
opening the inlet valve ( 13 ) and providing a fluid having a first fluid pressure p 1 at the first fluid connector ( 23 ) and the pressure sensor ( 3 );
closing the inlet valve ( 13 );
carrying out a pressure measurement of the first fluid pressure p 1 at a time t 1 by means of the pressure sensor ( 3 );
opening the vessel valve ( 25 ) in order to fluidly connecting the second fluid connector ( 23 ) with the pressure sensor ( 3 ) and the first fluid connector ( 19 ), so that a second fluid pressure p 2 is provided at the pressure sensor ( 3 );
carrying out a pressure measurement of the second fluid pressure p 2 at a time t 2 by means of the pressure sensor ( 3 ).

11. The test device ( 1 ) of claim 10 , further comprising:
a first fluid storage vessel ( 17 ) fluidly connected to the first fluid connector ( 19 ) and/or
a second fluid storage vessel ( 21 ) fluidly connected to the second fluid connector ( 23 ).

12. The test device ( 1 ) claim 11 , further comprising:
calculation means ( 29 ), which are configured to determine the difference Δp 2 between the measured second fluid pressure p 2 and a predicted second fluid pressure <p 2 > predicted using the formula
< p 2 >=( p 1 V 1 +p 0 V 2 )/( V 1 +V 2 ),

wherein V 1 is the volume of the first fluid storage vessel ( 17 ) and wherein V 2 is the volume of the second fluid storage vessel ( 21 ).

13. The test device

Assignees

• Sartorius Stedim Biotech Gmbh
• Sartorius Stedium Biotech Gmbh

Inventors

• Stering Magnus

Classifications

• G01L27/002

  Calibrating, i.e. establishing true relation between transducer output value and value to be measured, zeroing, linearising or span error determination · CPC title

• G01L27/005 Primary

  Apparatus for calibrating pressure sensors · CPC title