CA1148648A - Measuring equipment for acoustic determination of specific gravity in liquids - Google Patents
Measuring equipment for acoustic determination of specific gravity in liquidsInfo
- Publication number
- CA1148648A CA1148648A CA000352573A CA352573A CA1148648A CA 1148648 A CA1148648 A CA 1148648A CA 000352573 A CA000352573 A CA 000352573A CA 352573 A CA352573 A CA 352573A CA 1148648 A CA1148648 A CA 1148648A
- Authority
- CA
- Canada
- Prior art keywords
- specific gravity
- disc
- transducer
- reference unit
- end faces
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/02—Indexing codes associated with the analysed material
- G01N2291/028—Material parameters
- G01N2291/02818—Density, viscosity
Landscapes
- Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
The specification relates to measuring equipment for the determination of the specific gravity of liquids. The equipment includes a transducer which is fitted in a measuring probe consisting of a tubular holder which also contains a reference unit in full contact with the transducer. A reflection disc is placed at some distance from the side of the reference unit opposite one face of the transducer. The tubular holder is slotted between the reference unit and the reflection disc so that there is at least one opening in the tube wall. The refer-ence unit has at least one all-round incision the limitation surface of which, facing the transducer, is parallel to the in-terface between the transducer and the reference unit.
The specification relates to measuring equipment for the determination of the specific gravity of liquids. The equipment includes a transducer which is fitted in a measuring probe consisting of a tubular holder which also contains a reference unit in full contact with the transducer. A reflection disc is placed at some distance from the side of the reference unit opposite one face of the transducer. The tubular holder is slotted between the reference unit and the reflection disc so that there is at least one opening in the tube wall. The refer-ence unit has at least one all-round incision the limitation surface of which, facing the transducer, is parallel to the in-terface between the transducer and the reference unit.
Description
The present invention relates to a measuring equipment for determination o~ the specific gravity of liquids and o~ the kind stated in the introduction of the claim.
The acoustic impedance of a liquia is the p~oduct o~ the specific gravity of the liquid and the propagation time of an acoustic wave in the liquid. This connection is utilized in specific gravity determination in apparatus in which a trans-ducer, e.g. a piezoelectric ceramic disc, transmits an ultra-sonic pulse over a given distance through the li~uid.
In measuring apparatus known so far this given distance is the distance between two walls of a measuring chamber, or twice that distance if the same transducer is used as both transmitter and receiver of the ultrasonic pulses. Such apparatus, e.g. known from the specifications of U.S. patents 3-028-749 and 2-926-522, require a relatively complicated and stationary measuring equipmentO
According to the present invention, the transducer is suggested to be fltted in a measuring probe comprising, a holder having a piezoelectric ceramic disc attached at one ~0 end thereof and a parallel arranged reflection disc attached ; at the other end thereof, a reference element having parallel end faces and a known acoustical impedance, the reference element having one of the end faces in abutting engagement with the piezoelectric disc and the other of the end faces ; in spaced relation to the reflection disc to form a sampling space therebetween, the reference element having an annularly shaped groove formed therein intermediate the end faces and having a planax surface adjacent to and parallel to the s d /~J~
- .
ceramic disc, the holder havin~ wall means boun~ing and surrounding the annular groove, and the wall means forming an opening to provide ingress and egress to and from the sampling space for a medium externally of the probe.
Through this, a simple and mechanically stable measuring equipment is obtained, and it is easily portable because the measuring probe may be the size of an ordinary ball-point pen. Through the electronic circuit, the specific gravity of a liquid, in the space between the reference unit and the reflection dise, can be determined by measuring the refleetor amplitude from the transition between the referenee unit and the liquid and the propagation time of the acoustie wave in the liquid.
In the following, the invention will be explained in detail with refarenee to the drawing whieh shows a cross-seetion of a measuring probe as speeified in the invention, for acoustie determination of the specific gravity of liquidsO
The probe shown consists of a piezoelectric ceramic disc (1), a referenee unit (2) and a refleetion dise (3), fitted in a tubular holder (4). Between the referenee unit (2) and the reflection dise (3) the tubular holder (4) is slotted so .
that there is at least one opening (5) in the tube wall.
The eeramie dise (1) is conneeted to an eleetronie eircuit - not shown in the drawing - whieh can apply eleetrie pulses to the dise. Then, ultrasonic waves will be transmitted through the adjoining reference unit (2), pass through the open space between the referenee unit (2) and the refleetion disc (3), and be refleeted to the ceramic disc. Here, the acoustie signals will be converted into eleetrie signals whieh sd/ ~ -2-'18~;41 3 will be ~pplied to the elec~ronic circuit.
Thus, the ceramic disc (1) is used as both a transmitter and a receiver of acoustic pulses.
In the reference unit (2) there is an annular groove having a planar limitation surface (6) which faces the ceramic disc (lj and is parallel to the interface between the ceramic disc (1) and the reference unit (2), i.e. at right angles to the direction of sonic propagation in the reference unit (2).
When a short electric pulse is applied to the ceramic disc (1), an ultrasonic wave will be transmitted and propagated through the reference substance. Part of the sound will be totally reflected at the limitation surface (6~ if, on the other side of the limitation surface (6), there is a substance, e.g. air, the acoustic impedance of which is a great deal lower than the acoustic impedance of the reference substance which may, e.g., be glass, aluminium or stainless steel. The amplitude of Ao of the reflected echo will be proportional to the amplitude of the acoustic wave transmitted.
The remaining acoustic wave transmitted will be propagated through the reference substance and be reflected to the interface between the reference unit (2) and the medium which has permeated through the opening ~5) between the reference unit (2) and the reflection disc (3). Thus, if the measuring probe has been immersed in a liquid, the latter will be the substance adjoining the terminal surface of the reference unit (2).
B
sd/c~ -3-: ,. , . . .. ~ . . .:
T r a n s I a t i o n ~ 48 From this terminal surface a sonic wave is reflected, the amplitude Al of which can be expressed as follows:
Al - Aj ( p c + g~ c ) ( 1 ) in which e~pression A is the arnplitude of the sonic wave trans-mitted, ~)r and Pv designate the specific gravity of the reference unit and the liquid, and c and CV the corresponding propagation times.
From tl-e above expression tl ) the specific gravity ~'v of the liquid can be calculated, because ( A. - A ~ ) v r (Aj + Al ) x c (2) in which expression Zr designates the given acoustic impedance Srcr of the reference unit (2).
The part of the sonic wave which is not reflected by the interface between the reference unit (2) and the liquid, will be propagated through the latter and be reflected from the reflection disc to the ceramic disc (1). The propagation time in the liquid cv can be expressed as fol lows:
v T ( 3 ) in which expression I is the distance between the reference unit 12) and the reflection disc (3), and T is the propagation time, determined by~ the time lag between the sonic waves reflected.
Through the amplitude A the sound reflected from the limita-tion surface (6) the electronic circuit can adjust the transmission amplitude so that Aj will be constant irrespective of variations of the temperature-variable data of the piezoelectric ceramic d;sc (1).
On the basis of expressions (2) and (3) the specific gravity of the liquid can then be determined by measuring amplitude Al 9 or the voltage El proportional to that, and the propagation time T, because rTv (E j -- El ) Pv 2 X I (Ej ~ E~ where E; = const. x A;
4 ..... s -T _ a n s I a t I o n 5 Electronically, it may be difficult to get precise figures by analog multiplication and division of voltages, so the above expression (4) can be transcribed as fol lows:
v 2 x I X ~nor ~ 2 x I X r nor ~7~
in which expression Znor is the acoustic impedance of a normal solution, for which purpose water at 20 centi~3rade will be expedient. If the probe is immersed in water, the second term of the above expression (5) wiil be zero, and the specific gravity is determined by measuring the time. As the acoustic impedance of most liquids is of the same size as that of water, the last term of expression (S) is of minor importancè in the determination of the specific gravity. Consequently, any uncertainty in calculation of the last term will be negligible.
':
- -:. :
The acoustic impedance of a liquia is the p~oduct o~ the specific gravity of the liquid and the propagation time of an acoustic wave in the liquid. This connection is utilized in specific gravity determination in apparatus in which a trans-ducer, e.g. a piezoelectric ceramic disc, transmits an ultra-sonic pulse over a given distance through the li~uid.
In measuring apparatus known so far this given distance is the distance between two walls of a measuring chamber, or twice that distance if the same transducer is used as both transmitter and receiver of the ultrasonic pulses. Such apparatus, e.g. known from the specifications of U.S. patents 3-028-749 and 2-926-522, require a relatively complicated and stationary measuring equipmentO
According to the present invention, the transducer is suggested to be fltted in a measuring probe comprising, a holder having a piezoelectric ceramic disc attached at one ~0 end thereof and a parallel arranged reflection disc attached ; at the other end thereof, a reference element having parallel end faces and a known acoustical impedance, the reference element having one of the end faces in abutting engagement with the piezoelectric disc and the other of the end faces ; in spaced relation to the reflection disc to form a sampling space therebetween, the reference element having an annularly shaped groove formed therein intermediate the end faces and having a planax surface adjacent to and parallel to the s d /~J~
- .
ceramic disc, the holder havin~ wall means boun~ing and surrounding the annular groove, and the wall means forming an opening to provide ingress and egress to and from the sampling space for a medium externally of the probe.
Through this, a simple and mechanically stable measuring equipment is obtained, and it is easily portable because the measuring probe may be the size of an ordinary ball-point pen. Through the electronic circuit, the specific gravity of a liquid, in the space between the reference unit and the reflection dise, can be determined by measuring the refleetor amplitude from the transition between the referenee unit and the liquid and the propagation time of the acoustie wave in the liquid.
In the following, the invention will be explained in detail with refarenee to the drawing whieh shows a cross-seetion of a measuring probe as speeified in the invention, for acoustie determination of the specific gravity of liquidsO
The probe shown consists of a piezoelectric ceramic disc (1), a referenee unit (2) and a refleetion dise (3), fitted in a tubular holder (4). Between the referenee unit (2) and the reflection dise (3) the tubular holder (4) is slotted so .
that there is at least one opening (5) in the tube wall.
The eeramie dise (1) is conneeted to an eleetronie eircuit - not shown in the drawing - whieh can apply eleetrie pulses to the dise. Then, ultrasonic waves will be transmitted through the adjoining reference unit (2), pass through the open space between the referenee unit (2) and the refleetion disc (3), and be refleeted to the ceramic disc. Here, the acoustie signals will be converted into eleetrie signals whieh sd/ ~ -2-'18~;41 3 will be ~pplied to the elec~ronic circuit.
Thus, the ceramic disc (1) is used as both a transmitter and a receiver of acoustic pulses.
In the reference unit (2) there is an annular groove having a planar limitation surface (6) which faces the ceramic disc (lj and is parallel to the interface between the ceramic disc (1) and the reference unit (2), i.e. at right angles to the direction of sonic propagation in the reference unit (2).
When a short electric pulse is applied to the ceramic disc (1), an ultrasonic wave will be transmitted and propagated through the reference substance. Part of the sound will be totally reflected at the limitation surface (6~ if, on the other side of the limitation surface (6), there is a substance, e.g. air, the acoustic impedance of which is a great deal lower than the acoustic impedance of the reference substance which may, e.g., be glass, aluminium or stainless steel. The amplitude of Ao of the reflected echo will be proportional to the amplitude of the acoustic wave transmitted.
The remaining acoustic wave transmitted will be propagated through the reference substance and be reflected to the interface between the reference unit (2) and the medium which has permeated through the opening ~5) between the reference unit (2) and the reflection disc (3). Thus, if the measuring probe has been immersed in a liquid, the latter will be the substance adjoining the terminal surface of the reference unit (2).
B
sd/c~ -3-: ,. , . . .. ~ . . .:
T r a n s I a t i o n ~ 48 From this terminal surface a sonic wave is reflected, the amplitude Al of which can be expressed as follows:
Al - Aj ( p c + g~ c ) ( 1 ) in which e~pression A is the arnplitude of the sonic wave trans-mitted, ~)r and Pv designate the specific gravity of the reference unit and the liquid, and c and CV the corresponding propagation times.
From tl-e above expression tl ) the specific gravity ~'v of the liquid can be calculated, because ( A. - A ~ ) v r (Aj + Al ) x c (2) in which expression Zr designates the given acoustic impedance Srcr of the reference unit (2).
The part of the sonic wave which is not reflected by the interface between the reference unit (2) and the liquid, will be propagated through the latter and be reflected from the reflection disc to the ceramic disc (1). The propagation time in the liquid cv can be expressed as fol lows:
v T ( 3 ) in which expression I is the distance between the reference unit 12) and the reflection disc (3), and T is the propagation time, determined by~ the time lag between the sonic waves reflected.
Through the amplitude A the sound reflected from the limita-tion surface (6) the electronic circuit can adjust the transmission amplitude so that Aj will be constant irrespective of variations of the temperature-variable data of the piezoelectric ceramic d;sc (1).
On the basis of expressions (2) and (3) the specific gravity of the liquid can then be determined by measuring amplitude Al 9 or the voltage El proportional to that, and the propagation time T, because rTv (E j -- El ) Pv 2 X I (Ej ~ E~ where E; = const. x A;
4 ..... s -T _ a n s I a t I o n 5 Electronically, it may be difficult to get precise figures by analog multiplication and division of voltages, so the above expression (4) can be transcribed as fol lows:
v 2 x I X ~nor ~ 2 x I X r nor ~7~
in which expression Znor is the acoustic impedance of a normal solution, for which purpose water at 20 centi~3rade will be expedient. If the probe is immersed in water, the second term of the above expression (5) wiil be zero, and the specific gravity is determined by measuring the time. As the acoustic impedance of most liquids is of the same size as that of water, the last term of expression (S) is of minor importancè in the determination of the specific gravity. Consequently, any uncertainty in calculation of the last term will be negligible.
':
- -:. :
Claims
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A measuring probe for the acoustic determination of the specific gravity of a liquid, comprising, a holder having a piezoelectric ceramic disc attached at one end thereof and a parallel arranged reflection disc attached at the other end thereof, a reference element having parallel end faces and a known acoustical impedance, said reference element having one of said end faces in abutting engagement with said piezo-electric disc and the other of said end faces in spaced relation to said reflection disc to form a sampling space therebetween, said reference element having an annularly shaped groove formed therein intermediate said end faces and having a planar surface adjacent to and parallel to said ceramic disc, said holder having wall means bounding and surrounding said annular groove, and said wall means forming an opening to provide ingress and egress to and from said sampling space for a medium externally of said probe.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000352573A CA1148648A (en) | 1980-05-23 | 1980-05-23 | Measuring equipment for acoustic determination of specific gravity in liquids |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000352573A CA1148648A (en) | 1980-05-23 | 1980-05-23 | Measuring equipment for acoustic determination of specific gravity in liquids |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1148648A true CA1148648A (en) | 1983-06-21 |
Family
ID=4117017
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000352573A Expired CA1148648A (en) | 1980-05-23 | 1980-05-23 | Measuring equipment for acoustic determination of specific gravity in liquids |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1148648A (en) |
-
1980
- 1980-05-23 CA CA000352573A patent/CA1148648A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |