OPW 821 Anti Siphon Solenoid Valve 1 in. - 0 To 25 PSI

Normally Closed Anti-Siphon Protection for Aboveground Fuel Storage Lines

The OPW 821 is a two-way, normally closed diaphragm solenoid valve engineered to prevent accidental siphoning from aboveground storage tanks if a downstream fuel line is breached. It opens on energization to permit flow to a pump or dispenser, and returns to the closed position when de-energized, which makes it inherently fail-safe for fuel isolation. In data center facilities, the 821 is the right tool for securing the diesel fuel supply lines that feed emergency backup generators, where uninterrupted power is critical to maintaining active liquid cooling loops, CDUs, and IT infrastructure during grid outages. Wired into the generator control panel, it will permit fuel flow only when the generator calls for it and automatically seal the tank line on signal loss or power failure.

This valve is built for low-pressure petroleum service, with an aluminum body, Viton diaphragm and seals, stainless steel springs and core, Teflon rider rings, and an operating range of 0 to 25 PSI. It's suitable for gravity-fed and low-head fuel systems requiring zero minimum pressure to open. The optional 82RV thermal relief valve (factory-set at 25 PSI and field-adjustable from 5 to 30 PSI) can be integrated to vent line pressure caused by thermal expansion in exposed fuel piping.

Key specifications:

• Connection: 1 in. female NPT
• Operating pressure: 0 to 25 PSI
• Valve action: Normally closed, two-way diaphragm
• Body material: Aluminum
• Diaphragm, seals, and disc: Viton®
• Springs and core: Stainless steel
• Rider rings: Teflon®
• Disc holder: Nylon
• Core guide: Acetal/Delrin