There are instances where the hydraulic gradeline falls below a peak point during normal operation and where air inflow would adversely affect the normal operation and surge characteristic of the pipeline. Air intake may also be undesirable under pump trip conditions for pipelines running through a marsh (surge protection in these instances would be in the form of surge vessels and/or the pipeline will be designed for full vacuum).
Vent-O-Mat offers the Series RBXv valve which has specifically been developed to ensure effective air release under all pipeline conditions but will not allow air entry under any operating condition.
Air enters Orifice (1), travels through the annular space between the cylindrical floats (4), (5), (6) and discharges through the Large Orifice (3) into atmosphere.*
*Note: A relatively low flow discharge rate is required to lift float and ensure air release. Float will seat on the Middle Flange (9) under vacuum conditions, effectively preventing air entry.
In reaction to increased air flow, Float (6) closes Large Orifice and air is forced through the “Anti-Shock” Orifice resulting in deceleration of the approaching water due to the resistance of rising air pressure in the valve.
Subsequent to the filling of a pipeline, liquid enters the valve Barrel Chamber (2) and the Floats (4), (5) and (6) are buoyed so that the “Anti-Shock” Orifice (8) is closed by the Float (5) and the valve will then become pressurized. A minimal working pressure of