Vent-O-Mat - RGXII - Air Release Valves

The Vent-O-Mat Series RGXII "Anti-Surge" sewage air release and vacuum break valve, is an evolution of market feedback and the incorporation of the already proven Vent-O-Mat technology resulting from years of extensive research. The valve unlike many others is not just an adaption of an air valve to handle sewage, but the result of over 30 years of dealing with sewage and seeing what works and adapting it to the needs of the end user.

Features & Benefits

• High-capacity air discharge during pipeline filling
• High volume air intake for vacuum break purposes, both during draining of water pipelines and/or column separations
• Independent third-party tested
• Controlled pressurized air discharge releases air when pipelines are fully charged.
• Surge relief prevents pipeline bursts during pump trips & rapid pipeline filling.
• More compact & shorter to accommodate existing installations and retrofits.
• Designed for low head sealing where line pressures are generally lower than normal.

“Anti-Shock" - "Anti-Surge"-

The RGXII is an air release valve that is supplied as standard with a mechanism to prevent pipeline damage from the high-induced pressure transients associated with high-velocity air discharge. The surge resulting from liquid column separation and liquid oscillation is dramatically reduced as an automatic function of this mechanism. This same mechanism allows for controlled filling of the pipeline, maintaining controlled discharge at all times.

Compactness-

The RGXII is more compact and shorter without compromising the pressure rating of the valve.

Full Port Opening on Negative Pressure -

During pipeline draining and instances of surge, the valve will allow the intake of air to the full nominal bore of the valve. The RGXII series large orifice diameter equals the nominal size of the valve, i.e., an 8" valve has an 8" orifice. This ensures the least possible resistance to the intake of air and consequently the least possible negative pressure within a draining pipeline.

Sealing -

The RGXII has been designed for low-head sealing as well where line pressures are

generally lower than normal.

Material -

The RGXII is now available with a fusion-bonded Ductile Iron Body as well as a 304

or 316 Stainless Steel Body.

Performance -

The RGXII has been designed and developed to provide the optimum usable

and safe performance relative to all functions.

Quality -

The RGXII economically offers the highest quality construction and materials available in an air release and vacuum break valve. Stringent manufacturing and test procedures are maintained to ensure the best possible service and reliability is given by every valve produced.

Serviceability -

The RGXII design facilitates extreme ease of service and maintenance. Components are in corrosion-free materials to allow problem-free disassembly and reassembly even after many years of operation. All maintenance spares are replaceable without special tools or skills.

Available Configurations

• Standard – 4 functions
• Biased
• Flanged/Threaded Outlet

Typical Applications

Surge Protection-Initial Filling

The RGXII is always biased in the "Anti-Surge" mode meaning all air release is controlled through the “Anti-Surge” Orifice which is aerodynamically engineered to throttle air discharge when liquid approach velocity would otherwise become too great and induce an unacceptable pressure rise. The air throttling action increases resistance to the flow of the approaching liquid which consequently decelerates to a velocity that reduces the pressure rise when the valve closes (see operation below). Vent-O-Mat series RGXII is an essential precaution for pipeline priming.

Surge Protection - Pump Trip Conditions

In instances where a pipeline experiences liquid column separation due to pump stoppage, high shock pressures can be generated when the separated liquid column rejoins.

The Vent-O-Mat series RGXII takes in air through the unobstructed large orifice when liquid column separation occurs but controls the discharge of air/gas through the "Anti-Surge" Orifice as the separated column commences to rejoin. The rejoining impact velocity is thereby considerably reduced to alleviate high surge pressures in the system (see operation)

Other surge control measures may, dependent on pipeline profile, diameter, and operating conditions, be needed to provide the primary surge alleviation function with the Vent-O-Mat sewage air valves forming an integral and valuable addition in a combined strategy for further reducing surge pressures. The benefit of the "Anti-Surge" Orifice can be readily demonstrated by suitable surge modeling software.

Surge Protection - Pipeline Operating

The operation of valves and similar flow control devices can cause high-pressure transients in an operating pipeline. The unique, single-chamber design of the Vent-O-Mat series RGXII valve enables a pocket of air to be trapped in the valve.

chamber. The automatic operation of the small orifice control float regulates the volume of air entrapped. The volume maintained in the valve will provide a cushioning benefit to the pipeline for short-duration transient pressure "spikes". This effect can be modeled by the design engineer using suitable surge software.

Computer Modelling

The effectiveness of Vent-O-Mat “Anti-Surge” technology has been substantiated by independent third-party testing and by thousands of applications globally. Effective computer modeling, based on practical tests, has been ensured in the well-known and respected commercially available surge analysis software programs such as AFT impulse, FLOWMASTER, Waltham, and SURGE 2000.

Operation

PIPELINE FILLING (SUB CRITICAL AND EXCESSIVESEWAGE/ EFFLUENT APPROACH VELOCITY)

PIPELINE FULLY CHARGED

PRESSURIZED AIR/GAS RELEASE PIPELINE OPERATING

VACUUM RELIEF (AIR INTAKE) PIPELINE DRAINING

Selection & Positioning

THREADED INLET 2" & FLANGED INLET 2"- 8"

Type: Double Orifice (Small & Large Orifice) with Bias mechanism for large volume air intake and controlled air discharge.

Size & End Connection:

50mm - Female Threaded BSPT

80-200mm - Flanged AS4087 - PN16

Operating Temperature:

4.4 °C - 80 °C

Model Number / Operating Pressure Range

RGX II 1041 - up to 10 bar

RGX II 1641 - up to 16 bar

Overall Dimensions & Weights