Full-Circulation Ring Main Diverter Valve

Function

Correct valve operation ensures the bitumen is always in circulation through the ring main when the spray bar is not active, preventing cold zones, viscosity build-up in dead legs and pump cavitation. A sticking or leaking diverter valve is one of the most frequent root causes of uneven application rates and pump damage, because it allows unintended back-flow or short-circuit flow that undermines spray bar delivery pressure. The valve must also provide a clear flow path in fill and discharge mode without restricting the pump's rated transfer rate.

Construction & quality

Body: carbon steel or ductile iron with internal electrostatic epoxy coating for bitumen service. Ball or plug: 316 stainless steel, hard-chromed or PTFE-lined. Seats: PEEK polymer or PTFE-reinforced compound, rated to 230 °C (446 °F). Actuator options: manual lever with positive detented positions, or double-acting pneumatic at 4–6 bar on powered units. Stem seal: live-loaded PTFE chevron packing rated to 230 °C. Body size DN50 or DN65 (2" or 2½"). Body rated PN16.

When to replace

• Bitumen bleed between valve body halves in any switch position — seat wear or body distortion
• Pump delivery pressure is lower than expected in spray mode — valve not fully directing flow
• Valve handle requires high force to operate — carbonised bitumen hardened on the seat faces
• Visible drip from the unused port when valve is in spray or circulate position — seat leak
• Pneumatic actuator does not hold position under pressure — internal piston seal failure