Question 1

What is a plunger valve and how does it work?

Accepted Answer

A plunger valve is a specialized control valve featuring a sliding piston that is axially guided within the valve body, creating a perfectly ring-shaped symmetrical cross-section at every opening position. Optimized through Computational Fluid Dynamics (CFD), it delivers a linear control curve across 96% of its entire stroke, enabling precise downstream pressure control, flow control, and reservoir inlet management with minimal cavitation damage.

Question 2

What are the typical applications of SHIELD plunger valves?

Accepted Answer

SHIELD plunger valves are widely used in water distribution systems (bottom outlet valves of dams and reservoirs), hydropower plants (turbine bypass and surge anticipator valves), industrial process control (safety devices in bypass outlets), wastewater treatment (air flow rate control in aeration tanks), and drinking water systems (pilot-operated pressure-reducing valves without auxiliary power).

Question 3

What sizes and pressure ratings are available for the SHIELD Plunger Valve Series PLU?

Accepted Answer

The SHIELD Plunger Valve Series PLU is available in sizes from 2 inches to 60 inches, with pressure ratings up to Class 300. The body is made of ductile cast iron with a fusion bonded epoxy coating for superior corrosion resistance, and the valve meets NSF/ANSI 61 for drinking water applications.

Question 4

How does the plunger valve control cavitation?

Accepted Answer

The plunger valve intelligently splits flow into individual streams, directing energy conversion safely to the center of the pipe and away from vulnerable walls. Depending on the pressure differential, three control inserts are available: the Standard Type for low pressure difference and minimal cavitation, the Slotted Cylinder Type that dissipates cavitation harmlessly in the pipe or cylinder, and the Perforated Cylinder Type for enhanced cavitation control under high pressure drop conditions.

Question 5

What actuation methods are available for SHIELD plunger valves?

Accepted Answer

SHIELD plunger valves support manual operation, hydraulic control, and electric gear actuation. The actuation method is selected based on system requirements and can be customized for specific project needs.

Question 6

Are SHIELD plunger valves easy to maintain?

Accepted Answer

Yes. SHIELD plunger valves feature field-replaceable components including vaned rings, slotted cylinders, and perforated cylinder inserts. The main O-ring seal is located on the piston, safely recessed outside the cavitation zone for long-term sealing integrity. Four surface-hardened guides ensure uniform piston loading and minimal wear, even under vibration conditions.