Pressure indicator

A pressure gauge is provided for use with a swimming pool filter system to indicate the condition of the swimming pool filter and advise when changing of the filter element is necessary. The pressure gauge is also useful to remove trapped air within the filter system and relief any vacuum that may be built up within the system by permitting bleed air to pass into and out of the filter system.

BACKGROUND OF THE INVENTION 
A. Field of the Invention 
This invention relates to pressure gauges and particularly to means and 
methods for advising the pool owner of the condition of the swimming pool 
filter system and permitting bleed air into the filter system and 
evacuating air under high pressure from the filter system. 
B. Description of the Prior Art 
In swimming pools it is necessary to provide a filter system to remove 
foreign matter from the water thus providing a clean and aesthetically 
desirable swimming pool. This is accomplished by constructing a filter 
system remote from the swimming pool and pumping pool water from the pool 
through the filter system and back into the swimming pool. 
The filter system is customarily constructed of a tank which contains a 
filter element or elements arranged between the pool water inlet and pool 
water outlet of the tank. The filter element normally comprises either a 
series of particle screens or accumulations of diatomaceous earth 
contained within a series of cloth enmeshments. Because of its cost and 
effectiveness, diatomaceous earth has become the most favored material for 
use in the filter system. When using diatomaceous earth the tank is 
normally filled with the diatomaceous earth to a level below the top of 
the tank. 
Swimming pool water normally contains a great deal of air because of the 
turbulance caused by the use of the swimming pool. In addition, spas also 
require a filter system and these spas have water which has a high 
concentration of air bubbles because of the use of high powered jets to 
direct water into the spa. Consequently, the water entering the filter 
system of either a swimming pool or a spa is normally laden with air 
bubbles. 
After the air-laden pool water enters the filter system the filter element 
is useful to remove foreign particles from the pool water and trap the 
foreign particles, thus permitting only clean water to flow back into the 
swimming pool. The air bubbles in the pool water are also removed by the 
filter system and these air bubbles have a tendency to accumulate at the 
top of the tank above the filter element. 
When new the filter element permits the air collected above it to pass back 
into the filter system and out into the swimming pool after the filter 
system has been turned off. However, after the filter system has been used 
for a period of time, the filter element becomes dirty and clogged and 
prevents the passage of air back into the swimming pool. Thus, air 
pressure builds within the tank above the filter element. This pressure 
may be hazardous, because to change the filter element it is necessary to 
unbolt or otherwise unfasten the top of the tank containing the filter 
element and remove the filter element from the tank. If the pressure 
build-up is sufficiently high, the top of the tank may become a projectile 
and fly off of the tank possibly injuring the pool owner. 
It is also desirable to provide a filter system which will indicate to the 
pool owner the condition of the filter element and advise the pool owner 
when the filter element needs to be changed. 
Under certain operating conditions the filter system may also have a vacuum 
created within the tank, thus reducing the usability of the filter system. 
Therefore, it is also desirable to have a pressure gauge which will bleed 
air into the filter system to prevent the occurence of a vacuum within the 
filter system. 
It is well known that a valve may be provided with a filter system above 
the filter element to bleed air out of the tank. However, pool owners 
often forget to open the valve prior to changing the filter element. This 
situation leads to possible problems as discussed above wherein the top of 
the tank may become a harmful projectile. 
It is also known that pressure gauges may be installed in the filter system 
to advise the pool owner of the condition of the filter system. However, 
these pressure gauges do not have the ability to bleed air in and out of 
the system, thus leaving potential hazards. Furthermore, these pressure 
gauges are often difficult to read and thus pool owners are often 
reluctant to do so. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a pressure gauge 
capable of being set at one time to compensate for different pressure 
conditions occasioned by different plumbing, filters and pumps within a 
filter system as used with a swimming pool. 
It is a further object of the present invention to provide a pressure gauge 
which will advise the pool owner of the condition of the filter element 
and advise the pool owner when the filter element needs to be cleaned or 
changed. 
It is another object of the present invention to provide a pressure gauge 
which is operative to automatically bleed air out of the filter system to 
prevent the occasion of a high pressure air build-up within the filter 
system and the potentially hazardous results when changing filter 
elements. 
It is another object of the present invention to provide a pressure gauge 
that leaks air out of the filter system at the time of system start-up and 
automatically bleeds air back into the filter system to assist in the 
break-up of filter element cake thus insuring longer filter life cycle. 
The above objects are achieved by employing a combined pressure relief line 
with a pressure gauge to form a single integral unit. The unit is attached 
to the top of the filter system tank and provides constant monitoring of 
the filter system and equipressure operation. 
A slidable piston assembly is movable within the pressure gauge but is 
biased into contact with the lower portion of the gauge. The piston 
assembly is hollow and has a ball bearing disposed at its lowermost 
portion. The piston assembly has an aperture disposed along its length to 
permit passage of air from the filter system out through the piston 
assembly and out a relief line provided with the pressure gauge, thus 
causing bleed air to pass out of the filter system when the pump is turned 
on. When the pump is turned off the piston assembly is adapted to provide 
for bleed air to pass into the filter system to maintain equipressure 
within the system. 
The upper portion of the pressure gauge is clear to permit the pool owner 
to observe the position of the piston within the pressure gauge. 
Indicating lines may be supplied at the top of the gauge which will show 
the pressure within the filter system as the top of the piston assembly 
moves along the indicator lines. Thus, the pool owner is continuously 
advised of the pressure within the filter system. 
A relief line is provided along the pressure gauge to assist in bleeding of 
air out of the filter system and bleeding of air into the system in 
accordance with the operation of the filter system. 
In operation the ball bearing will move to permit passage of air out of the 
filter system and out of the relief line into the atmosphere. Upon turning 
on the pump of the filter system, water will eventually cause the ball 
bearing to seat in the bottom of the piston thus restricting air passage 
out of the filter system and causing the piston to move within the gauge 
to advise the owner of the pressure within the filter system. The pressure 
gauge spring may be calibrated to associate particular pressures within 
the system with the position of the piston within the pressure gauge.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIG. 1, there is shown a cross section of the invention of the 
present application as it is used in a swimming pool filter system. 
Briefly, the pressure gauge 10 is provided along the top 12 of the tank 14 
of a filter system as used with a swimming pool or spa. Bolts (not shown) 
or other clamping or attachment mechanisms may be provided to secure the 
top 12 to the tank 14. Within the tank 14 an accumulation of filter 
element material 19 is present to provide for filtering and cleaning of 
the swimming pool water. 
Customarily the filter element 19 is comprised of a series of clothes (not 
shown) which have a substantial amount of diatomaceous earth between each 
cloth. In other embodiments, the diatomaceous earth may be placed in a 
series of bags and placed within the tank 14. An inlet 16 is provided to 
direct the flow of water into the filter element 19 and an outlet 18 is 
provided to direct the flow of water from the filter element 19 and back 
into the swimming pool. A pump 20 is operative to cause water to move from 
the swimming pool and push the water into the filter element 19. Other 
pump mechanisms (not shown) may be provided to pull the water from the 
filter element 19 and return the water to the swimming pool. 
Referring to FIG. 2, the pressure gauge 10 of the present invention is 
shown in cross section as attached to the top 12 of the tank 14. An 
aperture 22 is provided in the top 12 of the tank 14. The top 12 
surrounding the aperture 22 is threaded to receive a nipple 24 which is 
attached to the lowermost portion of the pressure gauge 10. The nipple 24 
has at its upper portion a threaded section 26 which is receivable into a 
lower threaded section 28 of the pressure gauge 10 and provides for the 
secured fastening of the nipple 24 to the pressure gauge 10. Appropriate 
sealing means (not shown) may be provided between the nipple 24 and the 
pressure gauge 10 to prevent the leakage of fluid from the pressure gauge 
10. 
The pressure gauge 10 comprises a lower portion 30 which extends upwardly 
from the nipple 24 and meets an intermediate portion 32. The lower portion 
30 and intermediate portion 32 are attached to each other at the threaded 
section 34. Between the lower portion 30 and the intermediate portion 32 a 
seal (not shown) may be provided. Extending outwardly from the 
intermediate portion 32 is a bleed line 40 which permits passage of air 
out of the pressure gauge 10 into the atmosphere and from the atmosphere 
into the pressure gauge 10. The line 40 may have a hose 42 attached to 
direct the air to the desired location. Serrations 44 are provided between 
the line 40 and the hose 42 to rigidly fix the hose 42 to the line 40. 
The intermediate portion 32 has an upwardly extending cylinder 50 which 
resides within an upper portion 52 of the pressure gauge 10. The upper 
portion 52 and cylinder 50 are concentric with each other with appropriate 
attachment means (not shown) provided at the lowermost section of the 
upper portion 52 and cylinder 50. The upper portion 52 is constructed of 
clear plastic so that it is possible to view the inside of the cylinder 
50. A plurality of lines 54 may be provided on the uppermost portion of 
the cylinder 50 to indicate pressure graduations in the pressure gauge 10. 
A slidable indicator 56 may be provided around the cylinder 50 which is 
movable in an upward and downward direction to indicate the pressure at 
which the pool owner should change the filter element 19. 
A piston 60 is slidable within the pressure gauge 10 and moves in an upward 
and downward direction within the lower portion 30, the intermediate 
portion 32 and the cylinder 50. The piston 60 has an extended shoulder 62 
at its lowermost side and within that extended shoulder there is provided 
a channel 64. Disposed within the channel 64 is a ball bearing 66 which is 
movable from a position wherein it is not seated within the channel 64 to 
a position where it seats within the channel 64 against the piston 60 thus 
closing off a channel 68 contained within the piston 60. 
A spring 70 is disposed between the intermediate portion 32 and the upper 
surface 61 of the extended shoulder 62 and is operative to bias the piston 
60 into the lowermost position within the pressure gauge 10. The spring 70 
may be calibrated such that movement of the piston 60 against the action 
of the spring 70 will indicate a pressure within the filter system. At the 
uppermost portion of the piston 60 a plug 72 is provided which may be made 
of colored material to indicate the position of the piston 60 within the 
cylinder 50. The plug 72 will pass along the indicator lines 54 contained 
within the upper portion of the pressure gauge 10 to indicate the pressure 
within the filter system. 
A bleed hole 76 is provided along the shaft of the piston 60 and provides a 
passageway for air to pass through the channel 68 of the piston 60 and out 
the line 40. Sealing elements 78 may be provided at the uppermost portion 
of the piston 60 to prevent passage of air into the upper portion of the 
cylinder 50. The sealing elements 78 are also operative to guide the 
piston 60 through the cylinder 50. In the preferred embodiment, sealing 
elements 36 are also provided within the intermediate portion 32 to seal 
the passage-way between the piston 60 and the intermediate portion 32. 
In operation, the pump 20 is turned on permitting fluid to pass into the 
filter tank 14 and through the filter element 19. In the start-up 
condition, the line 40 will permit air to pass out of the gauge 10, thus 
the pump 20 is pushing against atmospheric pressure. This extends pump 
life. As the water is pumped through the filter element 19, the trapped 
air bubbles within the water are collected in the upper portion of the 
tank 14 above the filter element 19. These air bubbles without the 
presence of a pressure relief system would cause a high pressure to be 
created within the upper portion of the tank 14, thus creating a hazard 
when the pool owner desired to remove the top 12 to replace the filter 
element 19. Therefore, the pressure gauge 10 of the present invention is 
provided within the top 12 of the tank 14 to indicate air pressure within 
the tank 14 and also to provide a bleed capability to remove the high 
pressure air from above the filter element 19. 
Referring to FIGS. 1 and 2, as the pump 20 is turned on, the air that is 
contained above the filter element 19 passes through the aperture 22 and 
into the pressure gauge 10. The air causes the ball bearing 66 to rise 
slightly within the piston 60 and the air will pass around the ball 
bearing 66 and into the channel 68. Once the air is in the channel 68, it 
passes through the aperture 76 and out of the line 40. Thus, any trapped 
air above the filter element 19 will be relieved through the use of the 
pressure gauge 10. 
As the pool water fills the tank 14, the water will also pass through the 
aperture 22 and into the pressure gauge 10. As the water passes into the 
pressure gauge 10, it causes the ball bearing 66 to seat in the channel 64 
against the piston 60. Some water may pass between the lowermost portion 
30 and the piston 60 and be retained there. However, as the water pressure 
builds within the filter system, the piston 60 will move upwardly against 
the biasing action of the spring 72. As the piston 60 moves upward, it 
provides an indication of the pressure within the filter system. It should 
be noted that, most pool filters operate at 10 to 20 lbs. pressure. As the 
filter element becomes dirty and clogged, the pressure increases, thus the 
piston 60 will move further up within the pressure gauge 10 and provide an 
indication to the pool owner of the cleanliness condition of the filter 
element 19. 
When the pump is turned off, the water pressure within the filter system 
drops and the ball bearing 66 will unseat from the lowermost portion of 
the piston 60. Thus, bleed air is permitted to pass through the line 40 
through the aperture 76 and back into the tank 14. In this manner a vacuum 
is not created within the filter system and removal of the top 14 is 
facilitated. 
Use of the present invention provides many benefits to the pool operator. 
Because of the easy passage of air into and out of the piston assembly 60, 
the filter element 19, which customarily comprises diatomaceous earth, is 
constantly stirred up thus increasing the cycle time between cleaning of 
the filter element 19. Furthermore, because of the ability of the pressure 
gauge 10 of the present invention to relieve trapped air above the filter 
element 19 it is possible to place more filter element 19 within the tank 
14. 
In accordance with the objects of the present invention, the pressure gauge 
10 advises the pool owner when the filter element 19 needs to be cleaned 
because the piston 60 will move into a position within the cylinder 50 
which will illustrate the operating pressure of the filter system. 
Finally, the ability of the pressure gauge 10 to automatically permit 
passage of air into and out of the filter system will provide the ability 
to reduce the pressure within the filter tank 14 and also reduce the 
possibility of a vacuum being created within the filter tank 14. 
By setting the slidable indicator 56 along the cylinder 50, it is possible 
to advise the pool operator when the filter element 19 needs cleaning. 
Thus, the pressure gauge 10 is capable of being set at one time to 
compensate for differential pressures caused by the different plumbing, 
filters and pumps used within the filter system. 
Although one example of the present invention has been shown by description 
and illustration, it should be understood that there are many other 
arrangements and embodiments of the present invention within the scope of 
the following claims.