Measuring and testing – Specific gravity or density of liquid or solid – Float operated indicator
Reexamination Certificate
2001-06-26
2003-05-13
Muller, Richard A. (Department: 2856)
Measuring and testing
Specific gravity or density of liquid or solid
Float operated indicator
Reexamination Certificate
active
06561026
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to hydrometers and more particularly to a hydrometer for measuring a specific gravity of sea water contained in a fish tank.
BACKGROUND OF THE INVENTION
A conventional hydrometer for measuring a specific gravity of sea water contained in a fish tank is shown in FIG.
1
. The hydrometer comprises a transparent, thin and flat liquid container
1
open to the top, an axis
2
coupled to the surface of liquid container
1
, a pointer
3
having one end pivotably mounted on axis
2
, a weight
4
on pointer
3
located between axis
2
and pointed end of pointer
3
, and a graduated scale
5
adjacent one side pointed by pointer
3
. In use, dip liquid container
1
into sea water to cause water to flow from the top opening into the container
1
. This may force pointer
3
to displace for indicating the specific gravity of sea water when the liquid level in liquid container
1
has reached the pointed end of pointer
3
. Further, a preparation of the specific gravity of sea water is necessary so as to meet requirements. However, the previous hydrometer suffered from a couple of disadvantages. For example, the times of necessary preparation are unacceptable high. Further, air and liquid may mix to form bubbles as liquid container
1
dipped into sea water since water flows from the top opening into the container. Such bubbles tend to adhere to pointer
3
, thus adversely affecting the accuracy of reading of graduated scale
5
.
U.S. Pat. No. 5,631,420 to Wong discloses a hydrometer provided with a measuring chamber and a concealed liquid sample intake pipe having a bottom open end and a top open end. By dipping the bottom open end in liquid, the liquid is forced to flow from the bottom open end through the top bottom open end into the inside of measuring chamber to force pointer 3 to displace and to indicate the specific gravity of the liquid. It is advantageous for avoiding the operator's hand from being contaminated. However, above drawbacks such as higher times of preparation and the presence of bubbles still exist. Thus, it is desirable to provide an improved hydrometer in order to overcome the above drawbacks of prior art.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a hydrometer comprising a transparent container including a top opening, a pair of opposite arcuate dividers extended from both sides of the top opening for dividing an interior space of the container into a measuring chamber and a pair of opposite channels abutted side walls of the container, each channel having a bottom open end in fluid communication with the measuring chamber and a top inlet open to outside, and a pointer pivotably mounted inside the measuring chamber and adapted for indicating a specific gravity of liquid contained in the measuring chamber wherein a fluid path is formed from the top inlet through the channel and the bottom open end into the measuring chamber as the container immersed in the liquid to be measured. In operation, air in measuring chamber is evacuated from top opening gradually as liquid level in measuring chamber rises, thus avoiding the generation of bubbles. Further, operator can visually clearly read the specific gravity of liquid (e.g., sea water). Hence, operator can precisely determine the time(s) of necessary adjustment of the specific gravity of sea water in fish tank for meeting requirements. As a result, time and labor are saved.
REFERENCES:
patent: 4697454 (1987-10-01), Lu
patent: 5631420 (1997-05-01), Wong
Muller Richard A.
Pro-Techtor Inter-national Services
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