Secure-Gard™ Model 1049

The Model 1049 Pilot Operated Vent Valve (POVV), while being balanced against outlet header pressure, has some operating restrictions relative to the ratio of the outlet header pressure to the set pressure. The reason is that in order for a pilot operated main valve to open, the actuator or “dome” pressure must be reduced sufficiently. If the pilot exhausts to the atmosphere the valve can open if the header pressure is less than the set pressure. If the pilot exhausts to the outlet header the dome pressure can never get lower than the header pressure. And if the header pressure is relatively high, the dome pressure may not be able to get low enough to allow the main valve to open.

Therefore, as a rule the thumb, whether the pilot discharges to the atmosphere or to the outlet header in order for the [fixme] to achieve full opening, the header pressure must not be more than 25% of the set pressure of the POVV. On the other hand, vacuum in the outlet header will assist the opening of the main valve.

The relieving capacity of the valve is not based on the set pressure alone, but also takes into consideration the outlet header pressure, i.e. pressure drop across the main valve.

Line Sizes (Inlet Size x Outlet Size):

• 2″ x 3″
• 3″ x 4″
• 4″ x 6″
• 6″ x 8″
• 8″ x 10″
• 10″ x 12″
• 12″ x 16″

Body Materials:

Carbon Steel and Stainless Steel

Spring Ranges:

• 4.00″ – 11.9″ w.c.
• 12.0″ – 17.9″ w.c.
• 18.0″ – 35.9″ w.c.
• 36.0″ – 41.7″ w.c.
• 41.8″ – 86.0″ w.c.
• 3.2 – 14.0 psig

Elastomers: