| Sliding
Top Valve The Harbison-Fischer Sliding Top Valve is an elegant solution to the problem of gas locking and is helpful in fluid pound conditions. It has a free-floating, hard bronze sleeve that rides up and down on the valve rod, in a steel housing. On the pumping downstroke,
the sleeve follows the valve rod down and seals off the hydrostatic
pressure from above by shutting off the fluid flow passages through
the housing. This simple action removes the hydrostatic pressure load
from the traveling valve and allows it to open at the beginning of the
downstroke without the need to build up a high pressure in the compression
chamber. As with the Two Stage Hollow Valve Rod Pump and Gas Chaser
Pump, the fluid/gas mixture moves to the area above the plunger. |
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| On
the upstroke, this fluid/gas mixture above the plunger is compressed until
the sliding sleeve in the Sliding Top Valve opens and allows the fluid
to be discharged into the production tubing above the pump.
The Sliding Top Valve is also useful to cushion fluid pound. A part of the downward force that causes the destruction associated with fluid pound is the hydrostatic pressure above the plunger acting on part of the plunger area. The Sliding Top Valve holds back this hydrostatic head and thus reduces the load on the plunger when it contacts the fluid. It is available
for all sizes of insert and tubing pumps. The bronze sliding sleeve
is available with an abrasion resistant coating when particulates are
produced. |
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