Pressure Waves Don't Care About Your Budget:

How Velvetrol® Eliminates Water Hammer in Fluid Power Systems

If you've heard that unmistakable banging or hammering sound coming from your water, hydraulic, pneumatic, or steam lines—especially when a large solenoid valve closes—you've experienced water hammer firsthand. What you heard was a pressure shock wave traveling through your system at speeds approaching the speed of sound.

Here's what most plant managers don't realize until it's too late: that brief, loud bang represents thousands of dollars in potential damage happening in milliseconds.

In the fluid power industry, where precision, reliability, and system uptime are everything, water hammer is one of the most underestimated threats to your bottom line. And yet, it's one of the most preventable.

Understanding Water Hammer: The Hydraulic Shock You Can't Ignore

Water hammer—also called hydraulic shock or hydraulic surge—occurs when an incompressible fluid flowing through a pipe or system is forced to stop suddenly. The result is a catastrophic pressure spike that can reach 10 to 20 times your system's normal operating pressure in fractions of a second.

Here's the physics: When a standard solenoid valve closes rapidly, the flowing fluid doesn't stop instantaneously. Instead, it experiences a violent deceleration, creating a pressure wave that reverberates through your entire system like a shockwave through steel.

The Real Cost of Ignored Water Hammer

The damage potential is staggering:

• Burst or cracked pipes that require emergency replacement
• Blown gaskets and leaking joints throughout your system
• Damaged pressure sensors, flow meters, and instrumentation (often the most sensitive, most costly components)
• Compromised pump impellers and destroyed drive shafts
• Ruptured expansion joints and collapsed pipe supports
• System downtime measured in hours or days, not minutes
• Safety hazards including personnel injury from escaping pressurized fluid

Consider this: A water hammer event in an industrial hydraulic system can generate pressure spikes exceeding 1,400+ PSI in just a single closure cycle. For a system operating at 87 PSI, that's a pressure multiplier of 16x—enough to destroy seals, crack castings, and tear equipment from its moorings.

One fluid power facility we worked with experienced a water hammer failure that resulted in over $50,000 in emergency repairs, lost production, and regulatory penalties—all traced back to a single valve closure.

Why Standard Direct-Acting Valves Fall Short

Traditional direct-acting solenoid valves close with extreme speed—often in 25 milliseconds or less. While this sounds good in theory, in practice it's a recipe for water hammer in fluid power applications. The valve shuts before the system has time to accommodate the pressure change, and the incompressible fluid has nowhere to go but to spike violently.

Comparative testing of standard solenoid valves reveals the problem starkly: some achieve closure times so rapid that they create pressure spikes of 1,400+ PSI, while others create multiple pressure pulses before the system stabilizes. The damage accumulates with every cycle.

Enter Velvetrol®: The Packless Piston-Pilot Technology That Stops Water Hammer Before It Starts

Velvetrol® is Gould's proprietary internal piston pilot-operated technology—and it's engineered to address the water hammer problem at its root.

Unlike direct-acting valves or packed gland designs, Velvetrol® uses a sophisticated internal piston mechanism that controls valve closure speed through a graduated pressure equalization process. Instead of slamming shut in milliseconds, Velvetrol®-equipped valves close in a controlled manner, allowing the system to gradually accommodate pressure changes rather than experience violent spikes.

How Velvetrol® Prevents Water Hammer:

1. Pilot-Operated Pressure Balancing
The internal piston design uses system fluid itself to assist in valve operation, creating a natural dampening effect. As the pilot pressure equalizes, the main valve closes progressively—not abruptly. This smooth, controlled closure dramatically reduces pressure spike intensity.

2. Packless Design Eliminates Leakage
Traditional packed gland designs can develop micro-leaks and resistance as they age, which unpredictably affects closure speed and can worsen water hammer over time. Velvetrol®'s packless design maintains consistent performance throughout the valve's service life—no packing adjustments needed, no degradation of closure characteristics.

3. Full-Port Flow Geometry
Velvetrol®'s full-porting design minimizes flow turbulence and resistance, which further reduces the kinetic energy in the fluid stream. Less kinetic energy means smaller pressure spikes when closure occurs.

4. Adjustable Slow-Close Options
For applications where water hammer remains a concern even with Velvetrol®'s base design, Gould offers configurable slow-close features that extend closure time to 1-2 seconds or longer, creating an exceptionally gentle transition and virtually eliminating pressure surges.

5. Proven Performance Data
Water‑hammer behavior depends on many variables: fluid properties, line length, diameter, wall elasticity, system pressure, and how quickly flow changes. Industry literature and calculation tools show that, under certain conditions, an abrupt closure can drive transient pressures several times higher than steady‑state levels.​

In Gould’s internal testing of Velvetrol®‑equipped valves in representative water and fluid power configurations, controlled closure profiles have produced single, substantially lower surge peaks compared with fast direct‑acting alternatives, and have avoided the multiple oscillating pulses often seen with very rapid closures. Exact values vary by system, so engineers should validate performance using application‑specific calculations and instrumentation.​

Why This Matters to Fluid Power Engineers and Operators

For System Designers: Water hammer prevention is no longer an afterthought—it's a design imperative. Specifying Velvetrol® from the outset eliminates the need for expensive downstream mitigation strategies like surge tanks, relief valves, or complex pilot systems. One solid valve choice simplifies your entire system architecture.

For Plant Operations Teams: Velvetrol® means predictable system behavior, fewer emergency calls, extended equipment life, and confidence that your hydraulic or pneumatic system will perform reliably shift after shift. No more mystery failures traced back to pressure spikes you didn't anticipate.

For Maintenance Managers: With Velvetrol®'s packless design, you're no longer chasing leaks or adjusting packing glands to compensate for degraded performance. Many facilities using properly applied, well‑maintained pilot‑operated solenoid valves report long service lives and fewer emergency interventions compared with earlier configurations that allowed frequent pressure spikes.​ Rebuilds, when needed, are straightforward and economical.

For Procurement Professionals: While Velvetrol®-equipped valves carry a somewhat comparable upfront cost to direct-acting alternatives, when you factor in:

• Dramatically reduced water hammer damage (cracked pipes, destroyed instruments, blown seals)
• Significantly extended component life 
• Reduced downtime and emergency repairs
• Lower maintenance labor costs
• Avoided regulatory penalties from system failures

—the total cost of ownership becomes dramatically favorable.

Gould Solenoid Valves: 75 Years of Engineered Reliability

Since 1951, Gould has manufactured precision solenoid valves in Indianapolis, Indiana, with a singular focus: engineering valves that perform reliably in demanding fluid power, municipal, wastewater, and industrial applications.

Our complete product line includes:

• M Series: Bronze construction with NEMA 4X watertight coils (standard), ideal for water, air, light oils, and general service
• Q Series: Bronze with multiple NEMA options (1, 4, 5, 7), offering environmental and hazardous location flexibility
• K Series: Investment-cast 316 stainless steel for corrosive service and high-pressure applications up to 1,000 PSI
• Custom Solutions: When standard won't work, we design and manufacture custom valves to your exact specifications

Most Gould valves feature Velvetrol® technology as standard, giving you water hammer protection in every configuration.

We're a fourth-generation family business where many employees have spent 30-40+ years with Gould. That's not industry standard—it reflects our commitment to quality and the pride every team member takes in standing behind what we manufacture.

The Bottom Line

Water hammer isn't an inevitable consequence of fluid power systems. It's a design problem with an engineered solution.

If your plant is experiencing pressure surges, unexpected component failures, or that characteristic hydraulic banging sound, you're looking at a system that's not optimized for reliability. Velvetrol® technology can change that picture dramatically.

The question isn't whether you can afford to address water hammer. It's whether you can afford not to.
 

Ready to minimize water hammer and protect your system's uptime and integrity?

Let's talk. We can discuss your specific fluid power application, system pressures, flow requirements, and performance goals—and explain how Velvetrol® can deliver the reliability and peace of mind your operation deserves.

Whether you need a standard M, Q, or K Series valve or a custom configuration engineered for your exact application, we're here to help. Because in the fluid power industry, pressure spikes aren't just expensive—they're unacceptable.

Let's protect your system together.