US2677480A - Combination volumetric burette - Google Patents

Description

May 4, 1954 s. B. WICZER COMBINATION VOLUMETRIC BURETTE Filed June 5, 1950 W Ella:

INVENTOR Patented May 4, 1954 UNITED STATES PATENT oFFrce COMBINATION VOLUMETRIC BURETTE Sol B. Wiczer, Washington, D. 0.

Application June 5,1950, Serial No. 166,159

Claims. 1

This invention is a continuation-in-part of my copending application Serial No. 557,471, filed October 6, 19%, now Patent 2,510,159, dated June 6, 1950, and relates to a volumetric measuring device and in particular to a combination volumetric burette and small Vernier burette or micro-burette. In my parent application I have described a burette combined with a microburette whereby titration of chemical substances may be performed either with the ordinary burette or alternatively, with the micro-burette of the two burettes may be inter-connected to allow a combined titration whereby the titration through one burette may be more accurately read from the combined volumes after intertransfer of fluid between burettes after titration.

According to the present invention the burette is constructed to allow a combined simultaneous titration for both burettes, the reading however, is obtained as combined volumes preferably from the micro-burette for extreme accuracy. Further, with the present construction, it is possible to titrate alone from the micro-burette.

Hence, with the construction herein improved titration is now possible because it is unnecessary to transfer fluid from the large burette to the small burette for a large burette titration in order to obtain micro-burette reading as disclosed in my parent application. It is only necessary to perform a large burette titration and take an immediate reading off the micro-burette for micro-burette accuracy.

It is accordingly the primary object of the present invention to provide a combination burette and micro-burette whereby titration may be directly effected as a combined titration with" micro-burette accuracy.

It is a further object to enable this construction to be used in simple micro-burette titration.

It is a further object to construct both burettea with completely automatic self-filling zero readand in section to show internal construction.-

thereof.

Fig. 2 shows the reverse side of the micro burette alone, indicating micro-burette calibration.

Fig. 3 is a section through the valve Showing? the internal construction thereof taken on a line 33, Fig. 1, the position of the valve shown in Fig. 3 being that where both burettes are interconnected, but no fluid flows through the outlet.

Fig. 4 is a similar view to Fig. 3 showing the valve position with fluid from the micro-burette only.

Fig. 5 is a similar view to Figs. 3 and 4. showing the valve position when both burettes are flowing.

Fig. 6 is a perspective view of the disassembled valve plug to show detailed construction thereof.

Referring to Fig. 1 the burette assembly .is shown mounted for automatic filling and comprises a large burette Iii, constructed of glass, plastic or other transparent material which is not necessarily, but may be calibrated if desired, on its cylindrical surface for readings at H. The preferred accurate calibration is on the micro-burette so that the calibration as shown at H may be rough if desired. The lower part of the tube may taper to a shank at E2 and depend substantially to the bottom of a supply reservoir for chemical solution it which comprises merely a bottle having a bored rubber or cork; resilient stopper It fitted into the neck i5 thereof for air tight reception and vertical support of the shank l2. For automatic displace ment of the fluid from the bottle I3, a second tube It is fitted through a parallel bore in the stopper M, which is open at the top H to vent the return supply of fluid and which has a side arm tube l8 connecting with a flexible aspirator bulb is conventionally constructed of rubber through a connecting piece of rubber tubing 2d. The shank of the burette l2 tapers to meet the burette at 2|, but is substantially separated therefrom through a partition 22 communicating only with a capillary tube '23 connected to the top thereof at 25. The upper end of the capillary tube 23 is sealed to a rounded bulb 25 comprising the top of the large burette at 26 for support of the upper end of the rather fragile capillary tube 23. Intermediate the ends, the capillary tube curves at 21 and is open at an accurately cut portion of the curve at 2B which accurately defines the upper limit of fluid to which the large burette and interconnected micro-burette will be filled. The large burette is further provided with a vent 29, venting return of excess fluid to the supply reservoir 13.

The lower end of the burette it, immediately above the partition 22, leads into a connecting tube 30 which communicateswith one or more passageways of a valve 3!, comprising a tapered wall 32 having close fit as by grinding therein for free, but fiuid tight rotation a valve plug 33. Vertically sealed to and rising from the valve assembly 3i and parallel to the large burette, is a micro-burette comprising a capillary tube 34, which consists of an accurately bored capillary tube having a total of only about 1 to cc., generally about 2 cc. of liquid capacity. The microburette 34 is fastened at the upper end to the large burette by any supporting means such as a fragment of glass 35, comprising a bracket, preferably of plastic or glass sealed at each end respectively to the top of the micro-burette and to the large burette. The micro-burette is opened at the top at 36 communicating thereby with the atmosphere. The micro-burette is calibrated on the front surface with micro-burette accuracy at 31, such calibration corresponding to the combined volumes of both burettes such that a reading taken from the micro-burette will indicate the volume of fiuid thathas passed out of the apparatus in a titration from both burettes. On the reverse side of the micro-burette is another calibration 38 as shown in Fig. 2, such calibration being the calibration of the volume of the microburette alone.

Extending forwardly from the valve casing 3i, as better shown in Fig. 3, is an outlet spout 35, a tube which tapers to a narrow tip 39, to allow visible accurate dropwise release of liquid. Control of fluid flow is in the multi-way valve plug 33 which is broken away in Fig. l to show the general -mounting of the valve plug as well as some or'thc internal ducts thereof. In the position shown in Fig. 1, the valve plug is set merely to inter-connect both burettes'through a groove-like duct 58 which may be merely a shallow gouge cut in the tapered surface of the valve plug 33, sufficient to allow fluid to easily flow from the large burette to the small burette. In this position no fluid can enter the outlet spout 38. Fig. 3 is an elevation in section through the valve showing this position thereof.

For further control of the fluid flow for operation of the combination of burettes and as best seen in Fig. 6, valve plug 33 is bored with two radial ducts 43 and 44 at about thecenter of the plug 33 which connect with each other at substantially right angles and lead radially from the center of the plug 33 to the periphery for alter nate inter-connection thereof with the central outlet spout 33. When the valve plug is rotated in the direction of the arrow on knob d5 of Fig. 6 90, two radial bores 45 and 4?, which similarly are bored from the periphery to a center portion of the plug 33 and which are inter-connected with both outlets 43 and through a longitudinal bore 48 are thus placed by rotation to the Vertical position, so that each of bores 45 and M are aligned with the micro-burette 3s and large burette l6 respectively. In such position duct 53 is aligned with the outlet 38 so that both burettes are connected to the outlet for simultaneous discharge of fluid. (See also Fig. 5.)

Still another duct 49 is bored from the pcriph- I cry to interconnect with ducts 43 and 44 through the central duct 48 and is further aligned with duct 46 so that when the knob 35 is completely reversed, i. e. at 180 rotation from the position shown in Fig. 1, the duct 49 alone will interconnect with the micro-burette 34. At this position duct 44 will have been aligned with the outlet spout 38 so'that now the titration is possible from the micro-burette alone. (See also Fig. 4.)

Cross sectional details showing the valve position when both burettes are flowing is shown in Fig. 5 and with the micro-burette alone is shown in Fig. 4.

In automatic operation and with the valve set as shown in Figs, 1 and 3, when the operator places his finger over the vent l1 and introduces air pressure into supply bottle [3 by squeezing the aspirator bulb l9, fluid will flow through the tube l2, into the capillary tube 23, and into the large burette through the capillar outlet 28, and thence into both burettes I0 and 34 by way of passages 36 and 4t, filling the same. After the fluid has passed into both burettes above the zero reading, operation of the aspirator bulb I9 is stopped, the vent I! is freed, and the fluid will return automatically through capillary opening 28 returning excess fiuid to the supply bottle [3 by way of capillary 23, until the fluid stands exactly at aero mark of the calibration.

For a large volume titration, rotation of the plug from the position of Fig. l in the direction of the arrow shown in Fig. 6 will align outlets to both burettes by way of now vertically positioned ducts 45, 4? and horizontally positioned outlet 43, so that fluid will pass throughthe outlet tip 35] until the'chemical analysis has been completed. The outer calibration 3'! on the micro-burette is such that the reading of the fluid level therein after titration will give an accurate reading of fluid volume discharged from both burettes which will be read through the capillary size meniscus of the micro-burette thus giving extreme accuracy for a large volume titration.

When it is desired to titrate with the microburette alone, then after filling both burettes as described from the position of Fig. l the valve is rotated in the opposite direction .to the knob arrowof Fig. 5 to bring outlet duct 49 vertically into communication with the micro-burette 34 while the central duct 44 communicates with outlet 38 as shown in Fig. 4. Thus, titration is efiected from the micro-burette alone and in this instance the reading may be obtained from the reverse side of the micro-burette calibrated at 38 as shown in Fig. 2 to obtain a micro-burette titration and reading thereof.

As thus described it is possible with the combination herein shown, to obtain in a large volume titration all the advantages of extremely accurate reading from a calibration upon a microburette tube, or when a micro-burette titration is desired alone, such titration may be effected independently.

Various modifications in burette construction may be substituted from practices otherwise known in the art. For example, and as pointed out in applicants parent application, the burette and micro-burette may be modified to avoid automatic filling where this is desired. For this purpose the automatic filling shank is removed and the bottom rounded off, the internal capillary tube 23 is removed and the enclosing portion 25 thereof at the top of the large burette it? may be removed to allow open top construction for merely pouring fluid into the top thereof.

Similarly, the cutting of ducts, 46, 47, 48, 49, 43 and 44 may be such as is conventional in the art, that is, the glass plug 33 may have its ducts cut at angles other than shown. For example, it is merely necessary to interconnect ducts 46 and 4'! with the outlet 43; and duct 48 with the outlet 44; so that, rather than out deeply into the body of the valve plug 33, the same may be accomplished by merely cutting peripheral grooves, whichever is more'convenient for interconnecting these ducts. Large scale rough calibration is shown on the large burette Ill. Such calibration is a mere convenience; it may be rough or accurate as desired, to give the operator at least a rough idea of how much fluid to release quickly before the alternate slow release of fluid as theend point is approached. However such calibration on the large burette is not essential for the operation of this device.

It is accordingly intended that the specific embodiment herein set forth in the drawings be regarded as exemplary and not limiting except as defined in the claims.

I claim:

1. In combination a volumetric chemical analysis burette of relatively large volume and a burette of relatively small volume, each comprising elongated transparent tubes, the small volume burette having a calibration indicating the volumetric contents of the combined volumes of both burettes, a discharge spout comprising a tube drawn to a capillary point for dropwise eilluence of liquid, a rotary multi-way plug valve communicating with both burettes and with said discharge spout, said multiway valve comprising a rotary plug having passageways therethrough interconnecting both burettes to each other only in one position thereof, interconnecting both burettes to each other and simultaneously with the outlet in a second position of the plug, and interconnecting only the smaller burette with the outlet in a third position of the plug.

2. The burette construction as claimed in claim 1, wherein the burette of small volume has two calibrations, the first measuring the combined fluid volume of both burettes and the second measuring the combined fluid volume of the smaller burette alone.

3. The burette construction as claimed in claim 1, wherein each burette has a calibration measuring the combined fluid volume of both burettes, and the smaller burette has an additional independent calibration measuring the fiuid volume of the small burette alone.

4. The burette construction as claimed in claim 1, wherein both burettes have means for automatically filling the same.

5. The burette construction as claimed in claim 1, wherein the large burette has a volume not exceeding about 100 co. the burette of smaller volume is a micro-burette having a total volume of 1 to 5 cc.

References Cited in the file Of this patent UNITED STATES PATENTS Number Name Date 197,017 Colmer Nov. 13, 1887 c9c,493 Olmstead Jan. 24, 1893 804,894 Soderlund Nov. 1, 1 5

1,074,795 Johnson Oct. 1913 1,2 2, 3 Brown Apr, 16, 1918 1,297,458 Garvey Mar. 1919 1,505,122 Allwardt Aug. 1 1924 1,642,623 Niven Sept. 13, 1 27 1,794,215 Titus Feb. 2 1931 1, 3, 4 Geyer Sept. 18, 193

2,089,796 Hoir et a1. Aug. 10, 1937 2,2 1,1 McKay Jan, 27, 1942 2,4 ,442 Mayo Aug, 6, 1946 2,493,757 Fish Jan. 10, 1950 2, ,159 Wiczer June 6, 1950

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