Control Valve for High Maintenance Environments

Product Announcement from DFT Inc.

Is your control valve budget being stressed due to high maintenance costs? Do you need better process control than your current valve offers? DFT has the answer.

Our unique straight-thru venturi design performs in the harshest applications. Maintenance can be performed in-line without expensive tools using our quick change trim.

Power plant applications include: soot-blower, attemperator spray letdown, feedwater control, boiler feedwater recirculation, drum level control, turbine drain, wet steam, and high pressure reduction.

Refinery and chemical applications include: abrasive slurry control, amine service, butadiene service, pitch blending, sour water, and quench water control. The presence of a Bernoulli pressure differential through the valve prevents suspended particles from collecting in the valve body. This keeps the valve clean and free of material deposits. Any suspended particles flowing through the venturi concentrate in the center of the fluid stream minimizing the erosive action of the fluid on critical valve services.

We are also sourced for aerospace, military test, pipeline, paper and steel industry applications.

Valve Operation:
In the full open position, the valve operates as a true venturi with the inherent high flow capacity and high pressure recovery characteristics. Flow is straight through the valve. The cage envelops the flow path while securely cradling the ball out of the fluid stream with four pads.

In the intermediate throttling position the Bernoulli pressure differential keeps the ball firmly seated and stable in the cage pads. The ball provides precise modulating control by eclipsing the seat orifice.

In the close throttling position, the ball is supported in three-point suspension by the two forward pads on the cage and the seat face. The seat face acts as a load bearing surface, permitting the ball to cam in and out of the seat. This three-point suspension keeps the ball in a very stable condition, preventing spinning and/or chattering. This same stable three-point suspension also permits extremely close control throughout the opening stroke, even during the first 5% of travel.

In the closed position, the system pressure moves the ball into the conical seating surface. Line contact between the ball and the seat creates an exceptionally tight seal. As pressure increases, the seating force increases. Additionally, a slight rotation of the ball during the initial opening travel results in a new sealing surface contacting the seat each time the valve is stroked. Temperature changes will not affect the tight shut-off due to the freedom of movement of the ball in the conical seating surface.

Additional Information:
DFT has created a quick guide to understanding the fluid conditions that will most heavily impact the control valve selection process. To see the eBook, please continue to our website.