Pumps – One fluid pumped by contact or entrainment with another – Liquid pumped by supplying or exhausting gaseous motive...
Reexamination Certificate
2001-08-16
2003-06-03
Freay, Charles G. (Department: 3746)
Pumps
One fluid pumped by contact or entrainment with another
Liquid pumped by supplying or exhausting gaseous motive...
C417S130000, C417S131000, C417S134000
Reexamination Certificate
active
06572340
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to improvements in pump assemblies and more specifically to improvements in secondary pressure drainers.
SUMMARY OF THE INVENTION
Pumps of the type to which the present invention relate generally are not newer se. Pressure motive pumps, generically known as secondary pressure drainers, are typically used to move steam condensate at or near saturation temperature. Centrifugal pumps do not perform well pumping liquids at saturation temperature because the pressure reduction at the pump inlet causes a fraction of the liquid to vaporize. The resulting two phase mixture reduces pumping capacity and causes severe wear on the pump's rotating components.
These devices are also used in pumping applications where arc-over sparks may ignite a volatile fluid and where the use of electrical motors or the like may be hazardous. They are also used in remote hard-to-get-at locations or areas.
These pumps are generally used when it is desired to move liquids to a higher elevation, higher pressure or great distances. Some applications include steam condensate from vacuum or low pressure systems, condensate systems with high back pressure, steam condensing equipment such as heat exchangers, condensers or turbines, remote installations such as tank farms and as indicated above, in applications where electricity is prohibited, such as underground steam distribution systems.
Broadly speaking, the pump utilizes a spring-loaded mechanism inside a pump body to control liquid removal when the pump starts to fill through an inlet check valve where a float in the housing is in a low level position, which as described in more detail hereafter, opens a vent valve and closes the motive gas supply valves. When the spring-loaded mechanism reaches the trip point and snaps over center, the vent valve closes and the gas supply valve opens simultaneously. As the liquid is pumped out through the outlet check valve, the float starts to drop. When the float reaches the switch point, the mechanism snaps over center, the gas supply valve closes and the vent opens allowing the filling process to repeat. This is a continuous, repetitive process for pumping fluids and the like. In accordance with the present invention, means are provided for ensuring repetitive operation of the spring-loaded mechanism over long periods of time even where erosion of some of the parts and friction between the parts tend to deter normal operation of the pump.
In a typical cycle of operation, when the tank is starting to fill with a liquid such as steam condensate through the inlet port, the float is in the down position opening a vent valve to expel working gas, so condensate can enter the tank. As the condensate fills the tank to a certain point, the float rises and shuts off the vent valve and opens the inlet valve for the working gas. The working gas, such as steam or air discharges the condensate out the outlet port. As the condensate flows out, the float returns to its down position and the cycle starts over. It is noted that the inlet port is a check valve which allows only the flow of gasoline into the tank. The outlet port is also a check valve which prevents the pumped fluid from flowing back into the pump body.
REFERENCES:
patent: 6099260 (2000-08-01), Reynolds
Armstrong, The Armstrong Pumping Trap, Nov./1997, Armstrong Fluid Handling Inc., Bulletin No. 230-C 15M, pp. 3 and 5.
Freay Charles G.
Sayoc Emmanuel
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