Top OEMs for Control Valves

Introduction

In municipal and industrial water and wastewater systems, the control valve serves as the primary mechanism for hydraulic regulation. Unlike isolation valves, which are designed for infrequent open/close cycles, control valves must dynamically modulate flow and pressure to maintain system stability, protect aging infrastructure, and ensure consistent delivery of potable water or efficient processing of wastewater. The proper selection and specification of these components are critical to the operational expenditure (OPEX) and reliability of the utility.

Control valves operate at the intersection of fluid dynamics and mechanical actuation. In water distribution networks (WDN), they function as Pressure Reducing Valves (PRVs), Pressure Sustaining Valves (PSVs), and flow control devices. Their primary role is to manage the hydraulic grade line, preventing over-pressurization that leads to pipe bursts and increased non-revenue water (NRW) through leakage, while ensuring adequate pressure for fire flow and peak demand. In wastewater applications, control valves manage pump discharge, prevent surge and water hammer, and regulate flow into treatment processes.

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The regulatory context further emphasizes the importance of these assets. The Safe Drinking Water Act (SDWA) and various environmental compliance standards require strict adherence to system integrity. A failed control valve can lead to backflow events, catastrophic main breaks, or sanitary sewer overflows (SSOs). Consequently, the engineering choice of an Original Equipment Manufacturer (OEM) is not merely a procurement detail but a strategic decision impacting the facility’s lifecycle costs. High-quality manufacturing, precision engineering of pilot systems, and the availability of support for complex hydraulic troubleshooting are paramount.

This article provides a technical analysis of the leading OEMs in the control valve sector relevant to water and wastewater. It avoids marketing rhetoric to focus on the mechanical characteristics, hydraulic performance, and maintenance realities that consulting engineers and plant operators face daily.

How to Select Control Valves

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Selecting a control valve requires a rigorous engineering approach that moves beyond matching pipe diameter. A 12-inch pipe does not automatically dictate a 12-inch control valve; in fact, line-sizing control valves is a common error that leads to poor performance. The following criteria outline the technical methodology for specification and selection.

1. Valve Function and Duty Cycle

Engineers must first define the control variable: upstream pressure, downstream pressure, flow rate, or level.
Modulation vs. On/Off: Most control valves in this sector are modulating. They hunt for a setpoint. The valve’s ability to modulate without hysteresis (the lag between input and output) is critical.
Low Flow Capability: A common challenge in municipal water is the vast disparity between day-time peak demand and night-time low flow. A valve selected for peak fire flow may operate in a “chattering” or unstable zone during low demand. Dual-valve stations (a smaller valve for low flow and a larger valve for high flow) or valves with specific rolling diaphragm designs or V-port trims may be necessary to handle high turndown ratios.

2. Pressure and Flow Conditions

Cv Calculation: The flow coefficient ($C_v$) must be calculated for minimum, normal, and maximum flow conditions. The valve should typically operate between 20% and 80% open during normal conditions.
Cavitation Analysis: In high-pressure drop applications (e.g., dropping pressure from 150 psi to 50 psi), the fluid velocity increases across the valve seat, causing pressure to drop below the vapor pressure of water. As pressure recovers downstream, vapor bubbles collapse, causing cavitation. This results in noise, vibration, and rapid erosion of the valve body and trim. Engineers must calculate the cavitation index ($Sigma$) and specify anti-cavitation trim (cages) if the risk exists.

3. Materials of Construction

Body Materials: For municipal water, Ductile Iron (ASTM A536) is the standard due to its strength and durability. For wastewater or aggressive industrial water, Stainless Steel (316/316L) or Duplex Stainless Steel may be required.
Coatings: Fusion Bonded Epoxy (FBE) is mandatory for ductile iron valves to prevent corrosion and tuberculation. The specification should call for internal and external coating, typically to AWWA C550 standards.
Elastomers: The diaphragm and seals are the primary wear parts. EPDM is standard for potable water (chloramine resistance). Buna-N (Nitrile) is preferred for wastewater where hydrocarbons or oils might be present.

4. Sealing Mechanisms and Internal Design

Globe vs. Angle Pattern: Globe patterns are standard for inline piping. Angle patterns offer better hydraulic characteristics (lower head loss) and can replace a piping elbow, reducing installation footprint.
Diaphragm vs. Piston:

• Diaphragm Actuated: Frictionless and highly sensitive to small pressure changes. Preferred for precise regulation in water distribution.
• Piston Actuated: More robust, often used in higher pressure or slower-acting applications. Pistons have seals that introduce friction (hysteresis), making them less responsive than diaphragms but potentially more durable in extremely high-pressure surges.

5. Actuation Requirements

Hydraulic Pilots: The vast majority of municipal control valves are self-actuated via hydraulic pilot systems. These use line pressure to control the main valve. The complexity of the pilot circuit determines the valve’s function (e.g., solenoid shut-off, check feature, two-stage opening).
External Actuation: For SCADA integration requiring remote setpoint changes, motorized pilots or full electric actuators are used. Pneumatic actuation is common in industrial plants with available instrument air but rare in remote municipal vaults.

6. Installation Environment

Vaults vs. Buried: Control valves are typically installed in concrete vaults for maintenance access. If a valve must be buried, it requires a specific “buried service” specification, usually involving heavy external coatings and extension spindles for pilot isolation, though this is not recommended for modulating valves.
Submersion: Vaults frequently flood. All external pilots, solenoids, and position indicators must be rated IP68 (submersible) to prevent electrical failure or corrosion.

7. Maintenance and Lifecycle Cost

Serviceability: Can the valve be serviced inline? Top-entry designs allow operators to remove the cover, diaphragm, and trim without removing the valve body from the pipeline.
Pilot Strainers: The most common cause of control valve failure is a clogged pilot strainer. Large surface area, self-flushing strainers significantly reduce operator maintenance trips.
Spare Parts: The availability of standardized rubber kits is a major lifecycle consideration. Proprietary or obsolete parts lead to premature valve replacement.

Comparison Table

The following table provides a comparative analysis of the top OEMs designated for control valves. This table is intended to assist engineers in understanding the core competencies and design philosophies of each manufacturer. It is not a numerical ranking but a qualitative guide to “best fit” applications.

Guidance on Interpretation:
• Core Design: Refers to the fundamental mechanical architecture (e.g., globe, axial, diaphragm type).
• Strengths: Highlights where the OEM outperforms general market standards.
• Limitations: Notes areas where the product line may not be the optimal engineering choice compared to specialized alternatives.
• Best-Fit: Identifies the specific scenario where this OEM is often the preferred specification.

Top OEM Manufacturers

The following section details the engineering attributes of the specific OEMs evaluated for the Control Valve category. These manufacturers represent the tier-one suppliers recognized for quality, compliance with AWWA standards, and long-term reliability in water and wastewater applications.

Cla-Val

Cla-Val is widely considered the pioneer and market leader in the automatic control valve industry, particularly within the North American municipal water sector. Their core technology revolves around the hydraulically operated, diaphragm-actuated globe or angle valve.

Engineering Analysis: The flagship “100-01” (Hytrol) valve is the chassis upon which almost all their applications are built. The engineering genius of the Cla-Val approach lies in the pilot system. By changing the external pilot tubing and control accessories, the same main valve body can function as a pressure reducer, pressure sustainer, relief valve, solenoid valve, or a combination of these (e.g., a solenoid-override PRV with check feature).

Key Technologies:
• Anti-Cavitation Trim (KO): Cla-Val offers a radial slot trim that directs colliding flow streams into the center of the valve, away from metal surfaces, dissipating energy and preventing damage during high pressure drops.
• Electronic Interface: The VC-22D and other electronic controllers allow the hydraulic valve to interface seamlessly with SCADA systems for remote setpoint modulation or time-based pressure management.
• Maintenance: The design is top-entry, meaning the cover can be removed to replace the diaphragm and disc without removing the valve from the line. The parts availability is extensive, often with backwards compatibility spanning decades.

Bermad

Bermad brings a distinct engineering philosophy centered on hydraulic efficiency and material versatility. While they compete directly with Cla-Val in the metal globe valve market (700 Series), they are also leaders in composite and plastic control valves, which offer distinct advantages in corrosive environments or lighter-weight applications.

Engineering Analysis: A significant differentiator for Bermad is the “Double Chamber” actuator design found in their Sigma and 700 series. Unlike a standard single-chamber valve where the closing force is provided by line pressure on top of the diaphragm against a spring, a double chamber allows for positive opening and closing pressure. This creates a valve that is extremely responsive to pressure changes but cushioned against slamming. It also allows the valve to operate fully open with very low head loss.

Key Technologies:
• Unitized Actuator: The diaphragm and internal mechanism often come as a single unitized assembly, simplifying field replacement and reducing the chance of assembly errors.
• Composite Materials: For applications involving brackish water, seawater desalination, or chemically treated wastewater, Bermad’s engineered plastic valves eliminate the corrosion issues associated with epoxy-coated iron.

Singer Valve

Singer Valve (now part of Mueller Water Products) has carved out a reputation for precision engineering, particularly in addressing the twin challenges of low-flow instability and cavitation. Their approach appeals to engineers dealing with complex hydraulic modeling where standard valves might hunt or erode.

Engineering Analysis: The cornerstone of Singer’s design is the Single Rolling Diaphragm (SRD). In traditional flat diaphragm valves, the rubber stretches and distorts, creating resistance (hysteresis). The SRD rolls rather than stretches, providing a constant effective area throughout the stroke. This results in extremely stable control, even at very low flows (near zero), without the chattering often seen in standard globe valves.

Key Technologies:
• Anti-Cavitation Cages: Singer’s dual-cage anti-cavitation trim is highly regarded. It uses two heavy stainless steel cages with drilled orifices to break the pressure drop into two stages, preventing vapor bubble collapse against the body wall.
• Total Automatic Process (TAP): Singer has integrated advanced electronics for pressure management, allowing utilities to modulate pressure based on flow demand, thereby reducing leakage in distribution grids.

Mokveld Valves

Mokveld operates in a different engineering stratum compared to the pilot-operated globe valve manufacturers. Based in the Netherlands, Mokveld focuses on Axial Control Valves. These are typically specified for the most demanding applications in the world: high-pressure transmission lines, severe surge relief, and critical infrastructure where failure is not an option.

Engineering Analysis: The Mokveld axial flow design features a streamlined flow path between the inner and outer body. The flow is not forced to make the tortuous “S” turn found in a globe valve. This results in very high capacity ($C_v$) for the valve size and significantly reduced turbulence and noise. The control mechanism is a pressure-balanced piston, which requires very low actuation force, regardless of the line pressure.

Key Technologies:
• Axial Flow Path: Eliminates the turbulence associated with globe valves, making it ideal for high velocities.
• Zero Cavitation Damage: Through specialized trim designs (multi-stage), Mokveld valves can handle immense pressure drops without cavitation damage.
• Weight and Size: These valves are generally lighter and more compact than equivalent capacity globe valves, although they are precision-machined instruments with a higher price point.

Flomatic Corporation

Flomatic Corporation is deeply entrenched in the municipal and rural water market, known for high-quality valves that comply with the “Buy American” provisions often required in US public works projects. While they manufacture a wide range of valves, their control valve offerings are noted for robustness and specific pump control applications.

Engineering Analysis: Flomatic’s strengths lie in the intersection of check valves and control valves. Their “Cycle Gard” series of constant pressure pump control valves is a staple for well pump applications. These valves prevent the rapid cycling of pumps (which burns out motors) by modulating flow to maintain a constant downstream pressure, regardless of demand.

Key Technologies:
• Cycle Gard: A hydraulically operated valve designed specifically to extend the life of submersible pumps and booster pumps. It includes an inherent check valve function.
• Simplicity: Flomatic designs tend to prioritize fewer moving parts and simpler pilot systems, which is advantageous for smaller municipalities with limited maintenance staff.
• Unleaded Bronze/Stainless: Flomatic has been a leader in converting product lines to lead-free alloys well ahead of regulatory mandates.

Application Fit Guidance

To assist the consulting engineer in specification, the following section maps the OEMs to specific hydraulic environments.

Municipal Water Distribution (PRV Stations)

Primary Choice: Cla-Val, Singer Valve.
For standard pressure reducing stations, these two manufacturers offer the best balance of performance, support, and parts availability. If low-flow stability is the primary concern (e.g., a PRV feeding a residential zone with low night flow), Singer’s rolling diaphragm is technically superior. If the station requires complex functionality (e.g., PRV + Solenoid + Check + Rate of Flow), Cla-Val’s versatile pilot system is often the industry preference.

Municipal Wastewater (Pump Control)

Primary Choice: DeZURIK (Eccentric Plug – *see note*) or specialized Globe configurations.
Note: While DeZURIK is a leader in wastewater, among the locked list for this article, strict control valves in wastewater are difficult due to solids.
However, for clean water pump control or effluent applications, Cla-Val and Bermad offer specific “sewage” or “wastewater” versions of their valves. These feature separation chambers that keep the dirty fluid away from the sensitive diaphragm and pilot system, utilizing clean external water or oil for actuation.

High-Pressure Transmission & Surge Relief

Primary Choice: Mokveld Valves.
For large diameter (24″ and above) transmission mains operating at high pressures, or for critical surge relief where the valve must open in milliseconds to protect a pipeline from water hammer, Mokveld’s axial flow design provides a level of responsiveness and capacity that standard globe valves struggle to match.

Well Pumps and Booster Stations

Primary Choice: Flomatic Corporation.
For constant pressure control on well pumps, Flomatic’s Cycle Gard is the specific engineered solution. It is designed to work seamlessly with VFDs or as a standalone mechanical regulator to prevent pump cycling.

Corrosive Environments (Desalination/Brackish)

Primary Choice: Bermad.
When dealing with high chloride content that would attack standard 304 or 316 stainless steel, Bermad’s composite valves or nylon-reinforced plastic options provide a chemical resistance that extends lifecycle significantly compared to coated metal valves.

Engineer & Operator Considerations

Beyond selecting the manufacturer, the long-term success of a control valve installation depends on system design and operational practices.

Installation Best Practices

Straight Pipe Runs: Turbulence upstream of a control valve destabilizes the pilot sensing line. A general rule of thumb is to provide 5 pipe diameters of straight pipe upstream and 3 diameters downstream of the valve.
Isolation Valves: Gate or butterfly valves must be installed immediately upstream and downstream to facilitate maintenance.
Air Release: Air pockets in the control valve bonnet or pilot tubing cause erratic operation. Air release valves should be installed at high points in the vault piping.

Common Specification Mistakes

Oversizing: The most common error is sizing the valve to match the line size. A 6-inch valve in a 6-inch line may only open 10% to satisfy demand. Operating near the seat (wiredrawing) causes cavitation and seat damage. Engineers should size the valve based on $C_v$ to ensure the valve operates in the sweet spot (20-80% open).

Maintenance Access

Engineers must design vaults with the operator in mind.
• Can the cover be lifted?
• Is there a sump pump for drainage?
• Is there clearance above the valve to lift the heavy cover assembly?
Specifying a valve with a “Jack Screw” cover lifting feature (common in larger Cla-Val and Singer models) greatly aids maintenance crews.

Spare Parts and Reliability

Standardization has value. If a utility already has 500 Cla-Val PRVs, introducing 5 Bermad valves creates a need for new training and new spare parts inventory. Unless there is a compelling technical reason (e.g., a specific cavitation issue Singer solves, or a pressure issue Mokveld solves), sticking to the utility’s standard reduces operational complexity.

Conclusion

The selection of a control valve OEM for water and wastewater applications drives the hydraulic stability of the network. While the market features several high-quality manufacturers, they are not interchangeable in every application. Cla-Val remains the benchmark for general municipal distribution due to ubiquity and pilot versatility. Singer Valve excels in precision pressure management and challenging hydraulic conditions involving cavitation or low flow. Bermad offers unique advantages in efficiency and materials, particularly for corrosive or agricultural-crossover applications. Mokveld stands alone for high-end, high-pressure transmission and surge reliability. Flomatic provides robust solutions for pump control and smaller systems.

Engineers must move beyond “boiler-plate” specifications. By analyzing the specific hydraulic envelope—differential pressure, flow range, and fluid characteristics—and mapping these to the specific strengths of these OEMs, utilities can achieve systems that are not only compliant but operationally efficient and maintainable for decades.