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Mass Flow Control Valve

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Kurz - 730

Product Description

The Kurz Instruments series 730 valves are unique electrically-actuated loop-powered flow control valves. Unlike conventional electrical control valves, the Series 730 combines the electric drive motor, rotor, the valve body, and limit switches into a well-designed, integrated package.

The flow coefficient is nearly linear over a wide range due to its nearly 300° rotation between shut-off and full-open. The typical turn-down ratio is 50:1. Because of its rotary operation abrupt pressure changes do not affect the Series 730 nearly as much as conventional pneumatic control valves. A remarkable aspect of the 730 is its incorporation of a pressure-assisted shut-off feature which greatly improves the turndown ratio. The standard valve incorporates a high-torque DC gear motor; designed to be operated by any of the Series 155 Mass Flow Computers. The standard close-to-open time is 20 seconds. The standard allowable working pressure is 150 PSI and the temperature rating -40°C to +125°C.

The diameter, separation and the helical depth were designed to provide a nearly linear flow coefficient (Cv) with angular rotation. A simple high torque gearmotor (24 VDC) was selected for cost and simplicity. Since the Series 730 is a "fail-as-is" design, the motor is only used when changes are required, which greatly extends the motor life. The Series 730 combines the electric drive motor, the valve body, rotor and limit switches into a well-designed, integrated package. The typical turn-down ratio is 50:1, due to the incorporation of a pressure assisted shut-off disk which becomes active near the shut-off position. The Cv range is from 0.05 to 10.0 in three convenient body sizes.

The Series 730 is constructed of 316L stainless steel, with Viton O'Rings and an o'ring sealed motor cover. It operates as a two-wire loop-powered device normally powered and controlled by one of the Series 155 Mass Flow Computers and used with a Kurz In-Line Mass Flow Element. The inlet and outlet fittings are Schedule 40 pipe with MNPT end connections or Class 150 flanges. Because of its rotary design, the Series 730 is not as affected by abrupt line pressure changes as are pneumatic control valves.


State-Of-The-Art Air Sampling Systems
Chlorine metering
Petrochemical plants
Semi-Conductor Process
Gas Blending
Control of Argon and Helium in welding
Pilot plants
Aluminum and Steel Industry

Key Features 

Rugged integrated design
2-wire, loop-powered
316L SS construction
High Repeatability (±.25%)
Pressure rating:150 PSIG
Temperature rating of -40 to +125°C
Standard open-to-close time of 20 seconds (Faster is optional)
Meets nuclear requirements for seismic and environmental
Good shut-off capability

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