Measuring and testing – Instrument proving or calibrating – Fluid pressure
Patent
1996-12-18
1998-07-14
Oen, William L.
Measuring and testing
Instrument proving or calibrating
Fluid pressure
G01C 1738, G01L 1910
Patent
active
057807116
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention primarily relates to a gauge for use in liquefied gas systems for indicating when a predetermined quantity of liquefied gas remains in a storage tank supplying the gas.
A gauge for such a purpose is described in our European Patent 0052609.
The gauge includes a pointer moving over a scale; the pointer being moved by sensing means which continually senses the gas pressure in the storage tank. The scale on the gauge is shown in FIG. 3 of European Patent 0052609 as being divided into 3 regions 20, 21 and 22 corresponding to 3 zones B, C and D respectively of a graph shown in FIG. 1 of the present specification (which is a reproduction of FIG. 1 in European Patent 0052609). Whilst the pointer is in region 20 or 21a useful amount of liquefied gas is present in the storage tank.
A problem associated with a gauge having a pointer moving over a scale is that it can be confusing to read. This arises due to the fact that the gauge is continually exposed to variations in pressure within the system and as a result the pointer is continually moving across the face of the gauge dial.
It has been found in practice that users on seeing the pointer moving through region 20 toward region 21 mistakenly believe that the supply of liquefied gas is about to expire or believe that the movement results from a gas leak.
SUMMARY OF THE INVENTION
It is therefore desirable to provide a gauge which, although exposed to constantly changing gas pressures, shows only one reading whilst the gas pressure is above a first predetermined value corresponding to a first predetermined quantity of liquefied gas remaining in a storage tank and thereby gives a clear indication that the tank does not require changing.
The gauge desirably further only shows one reading whilst the gas pressure is below a second predetermined value corresponding to a second predetermined quantity of liquefied gas in said storage tank which is less than said first predetermined quantity and thereby gives a clear indication that the storage tank requires replacing.
The gauge desirably further shows a progressively variable reading inbetween said first and second predetermined values in order to give a progressive warning that liquefied gas contained in the storage tank is approaching, during use, said second predetermined quantity of liquefied gas.
According to one aspect of the present invention there is provided a pressure gauge including indicating means and pressure sensing means, the indicating means including an opaque screen and an indicator dial which are relatively movable, the screen and dial being relatively moved along a path of movement between first and second limits of movement in a progressive manner in response to variation of pressure sensed by the sensing means, the screen being arranged to mask the dial from view and being provided with a window through which a portion of the dial can be viewed during said relative movement along said path, the dial having two visibly distinct regions on its surface which is visible through the window, the visibly distinct regions being juxtaposed to one another along the path of movement, a first of said regions being arranged to be in registry with the window when the pressure sensed by the sensing means is at or above a first predetermined pressure and a second of said regions being arranged to be in registry with the window when the pressure sensed by the sensing means is at or below a second predetermined pressure which is lower than the first predetermined pressure.
Preferably the opaque screen is stationary and the dial is arranged to move along said path. The dial may be arranged to move along a linear or curved path. Preferably it is arranged to move about a circular path.
Preferably the dial is in the form of a disc mounted for movement about a central pivotal axis.
The window has a width dimension extending laterally of said path of movement and a length dimension extending longitudinally of said path of movement.
Preferably each of said visibly distinct
REFERENCES:
patent: 3757320 (1973-09-01), Heath
patent: 3990309 (1976-11-01), Beckwith et al.
patent: 4139278 (1979-02-01), Matsumoto et al.
patent: 4276776 (1981-07-01), Lapeyre
patent: 5119677 (1992-06-01), Porter
Gaslow International Limited
Oen William L.
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