Defender Series® P/V Vents

A pressure/vacuum vent decides when vapour may leave an underground tank and when air may enter it. If it leaks, vapour is lost and emissions rise; if it sticks, the tank can be over-pressurised during a delivery or pulled into vacuum as fuel is drawn. Franklin's Defender Series® vents use an internal rolling diaphragm so the poppet opens precisely at low pressure and then opens further to pass large volumes when pressure climbs.

Franklin says typical P/V vents last a single three-year test cycle and built the Defender Series from UV-resistant polymer with stainless steel screens to outlast that. A mesh-shielded rain cap keeps out water, insects and debris, an inlet screen protects the valve from the tank side, and a one-turn lock lets the valve be removed quickly.

There are two ways to install it. End-of-line, it threads onto a 2" vent stack with the supplied adapter and can also retrofit existing OPW® vent stack adapters. In-line, it sits inside an E-coated ductile iron vault at grade, behind a stainless steel faceplate with tamper-resistant screws and a drain plug for condensate. The vault removes the need for ladders or lift trucks, which matters because Franklin notes that almost half of industry injuries come from falls at height. US, UK and China cracking pressure versions are offered, and an EN ISO 16852 flame arrestor can be added. Apex selects the version that matches the site's vent design in Lebanon.