Uptime MFG

Reach Rods, Flexible Shafts, and Geared Systems

What is a Remote Valve Actuator (RVA)?

Uptime Mfg, LLC focuses primarily on mechanical Remote Valve Actuators, but RVA’s can be any combination of mechanical, hydraulic, pneumatic, or electrical systems used to open, close, or position a valve from a location other than that of the valve itself. Stem extensions, chain wheels, reach rods, motor-operators, air-operators, and solenoid valves are examples of RVA’s.

Why do I need Remote Valve Actuation?

Not all valves can be located at safe, comfortable operating locations that are convenient and accessible. Hard-to-reach valves are more common than one may expect and are often placed for process and safety requirements of the systems they control or obstructed by nearby systems. Many times, operation of hard-to-reach valves is resolved to maintenance and system shutdown where it is determined the valve won’t need to be operated frequently. But inaccessible valves can be a major safety concern when they need to be operated in an emergency situation and if it didn’t need to be actuated, there wouldn’t be a valve there.

Valves that are submerged, located in confined spaces, above or below human reach, located in radiated or contaminated areas, subject to harsh environmental or atmospheric conditions, or are otherwise obstructed are considered hard-to-reach.

Other times, Remote Valve Actuation is chosen as a convenience to bring operation of a complete system or related systems to one control panel, handwheel bank, platform, or elevation.

Types of Remote Valve Actuators

Manual valve actuation breaks down into two simple mechanical modes of operation: rotation and pulling. From a rotation standpoint, most of the valves we deal with operate using rotational input to a valve stem either directly or via a handwheel, lever, or third-party gearbox actuator. The pulling mechanic comes into play when looking at the handwheel of level of a valve from the standpoint of how one actually moves it. Rim pull is the tangential force that must be applied to the outside of the handwheel to rotate the valve stem.

Rotation Systems

Some of the most basic remote manual actuation systems are called “stem extensions” or “mechanical extenders” and are comprised of a rigidly coupled shaft to the valve stem and relocating the handwheel to the stem extension. In open space and when designed for, this arrangement is simple and efficient. For simply adding distance between the valve and the operator.

The next progression of this is a conventional rigid rod system. This is what is commonly envisioned with the term “reach rod”. Technically, a stem extension is a subset of the rigid rod category, but is treated differently from a historical simplicity standpoint. Rigid rod systems use universal joints, various gearboxes, swivel joints, couplings, and other mechanical components to deliver torque to the valve stem. Rigid has the false notion of being cheaper, but the reality is that in most applications, it is a lot more parts and far more complex to get it right.

The next progression in reach rods is the flexible shaft. “Flexible reach rods” or “Direct Flex” allow for complex routing and a substantial reduction in the number of RVA system components. These systems are prone to high torsional deflection and are larger diameter than their rigid rod counterparts to deliver the same operating torques, but are more forgiving in routing and operability. Direct Flex systems became popular in naval applications as they permit limited operation even after partial deck collapses that rigid rod otherwise would not.

Pairing the Rigid Rod or Direct Flex system to a third party gearbox or inline torque booster will reduce the required load on the RVA system and allow it to deliver greater amounts of torque to the valve.

Flexible shaft deflection is measured in degrees per foot per foot pound. Since manual valve operation of limited by the human factor, it is reasonable to assume that 60 rpm would be a reasonably sustainable speed of actuation. Speeding up the shaft would reduce the torque load on the shaft and in-turn the deflection, while simultaneously making a smaller shaft capable of delivering greater output torque when paired with gearboxes. This is called a “geared system” and is primarily offered as the optimal solutions for large valves and long runs.

Hybrid systems do not conform to any one type of actuation system and use a hybrid of parts from multiple RVA system types. The two most common hybrid systems are half-rigid and the other half direct flex or geared; and geared rigid, where the gear reduction theory of the geared flex system is used for rigid rods.

Pulling Systems

Consider being able to apply the tangential force remotely, from below the valve. A simple Chain Operator, “chainfall”, or chain wheel allows the valve handwheel to be rotated using a chain as a pulley. Some Chainfall operators use a secondary mechanism to allow input via a remote handwheel while others allow the chain loop to hang freely.

Being restricted to operation directly below the valve can be extremely limiting. Unlike chains that simply hang down in their place, routed mechanical controls cables can be used following more complex paths in “dual cable” systems. These systems allow greater flexibility than chainfalls and are best suited for applications with limited space above the valve handwheel when other solutions will not fit.

Remote Valve Actuation Solutions

RVA systems and components are highly customizable to accommodate your facility’s and operator’s unique needs. Whether you are maintaining, replacing, or installing new RVA systems, Uptime Mfg, LLC works with you and your facility to determine appropriate, economical solutions that conform with your facility requirements and various industry standards, including: ASTM F1166, MIL-S-16059B (Cancelled), MSS-SP-91, MIL-STD-1472H, API 6D, MIL-DTL-20625C, MIL-DTL-901E, IEEE 323, IEEE 344, IEEE 382, and ASME QME-1.

From replacement parts to turnkey solutions including walkdowns and installation support, rely on Uptime Mfg, LLC to be your Remote Valve Actuation experts.

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