Showing posts with label cavitation. Show all posts
Showing posts with label cavitation. Show all posts

CavFlo Cavitation Control Valve Trim by MASCOT

Whenever the pressure of flowing liquid through a restricted area of a control valve drops below the vapor pressure of the liquid, and recovers to a pressure above the vapor pressure, cavitation damage to the control valve and connecting piping may occur. 

In the first stage of cavitation, vapor bubbles form downstream of the restricted area at the vena contracta (point of narrowest fluid constraint). The enlarging passage at downstream of the vena contracta reduces the velocity and thereby associated pressure recovery causes the vapor bubbles collapse or implode suddenly.

This implosion of the bubbles on metal surfaces causes stresses, eventually resulting in tearing away particles of the metal from the surface towards inward. Cavitation damages the plug and seat of a control valve as throttling occurs at the restriction, in the clearance between the plug and seat ring. If the vapor bubbles implode near them, the valve body and piping can also be damaged.

MASCOT's CavFlo Trim utilizes many small holes for diametrical flow through the walls of the seat retainer. As the valve plug lifts, increasing pairs of holes are opened. Each hole discharges a jet of cavitating liquid at the center of the retainer, which impinges with a jet of liquid admitted through the opposing hole. The impinging fluid jets form an area of pressure recovery and a fluid cushion. This phenomenon collapses the vapor bubbles in the fluid stream, away from metal parts preventing damages.

For more information about MASCOT Control Valves, contact Mountain States Engineering and Controls. Call them at (303) 232-4100 or visit their website at

Regenerative Turbine Pumps

regenerative turbine pump for industrial use
Regenerative Turbine Pump
Roth Pump
Most of us are familiar with centrifugal pumps and their generally understandable operating design. A regenerative turbine pump is significantly different in the way in which liquid moves through the impeller section, enabling this pump type to prove advantageous in a number of industrial applications.

A centrifugal impeller basically traps some liquid at the inlet and rapidly slings through the discharge port. The liquid velocity is increased by the impeller and manifests as outlet pressure. The key distinction here is that the liquid enters and exits the impeller only one time. A regenerative turbine pump has an impeller with a comparatively larger number of vanes, also of a different shape. This shape imparts a circulatory movement of the liquid from the vanes to the casing, and back to the vanes. Each return to the vane section increases fluid velocity, which can be converted to increased pressure. As the impeller rotates, liquid enters, leaves, then re-enters the vane section many times. This process is called regeneration. The impact of this design is a pump that can deliver substantially greater pressure than a centrifugal pump with the same impeller diameter and rotational speed.

A regenerative turbine pump is capable of pumping fluids with up to forty percent entrained gases without damage from cavitation or any performance loss. Fluid conditions with even low levels of entrained gases would likely produce substantial loss of performance in a centrifugal pump, evidenced as fluctuating discharge pressure and excessive wear and vibration. Where cavitation is a concern, the regenerative turbine pump holds the advantage over centrifugal. Applications with low flow and high head requirements will also be better serviced by a regenerative turbine pump.

There is more to be learned. Some additional detail and explanation are provided in the document included below. Effective solutions are developed through a combining of your process knowledge and the application expertise of a product specialist. Reach out and share your fluid transfer challenges for the best solution.

Cavitation in a Water Pump and Valve - Excellent Visual and Audible Demo...

Cavitation is the formation of gas bubbles in a flowing liquid when the pressure of the liquid drops below its vapor pressure. Sometimes a difficult concept to grasp, this video offers an excellent demonstration on what actually happens inside process piping, pumps and valves during this phenomena.