Trans Zero Blanketing Valves (RA, Y1, BV-1)
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Trans Zero Blanketing Valves (RA, Y1, BV-1)

Description
Specifications
Documentation

Anderson Greenwood is a world leader in tank protection and blanketing. Anderson Greenwood has the experience and products to meet almost all blanketing and safety relief device needs. Furthermore, we can provide the Complete Blanketing and Safety Valve System including:

Pad and de-pad valves and regulators
Pressure/vacuum vents and low pressure pilot operated valves
Emergency vents and valves
Flame and detonation flame arresters

Because of the interactions between pad (blanketing) valves, de-pad (out breathing) valves, relief devices and flame arresters, each piece of equipment should be considered when specifying the blanketing system. Because of these interactions between components in the system, it makes sense to rely on one company to help specify and provide all of the products that make-up the complete pressure control system.

In fact, with many applications, it is possible to combine the functions of the de-pad valve and the pressure relief valves, thus minimizing the number of valves and tank connections. Moreover, Anderson Greenwood can provide pad, de-pad, flame arrestment and pressure/vacuum relief in a single tank penetration.

Features & Benefits:

Lower Installation Costs – Single unit system reduces labor and material costs
Simplicity of Setting Blanket Pressure – One unit to calibrate in lieu of conventional multi-unit systems
Reduced Maintenance Costs – Top entry provides access to all internal parts without removal from the line
Optimum Performance – Reduces supply gas pressure from 200 psig [13.8 barg] to 1/2" wc [1.2 mbarg] in one stage
Balanced Design – Accurately maintains setting regardless of pressure variations
Premium Tightness – O-ring seat and seals assure bubble-tight shut-off

Specifications

Connections:
Threaded (NPT) 1/2", 1", 2"
Flanged ANSI 150, 300, 600

Temperature Range: -20 to +300°F [-29 to +149°C]
Maximum Inlet Pressure: 200 psig [14 barg]
Blanket Pressure Range: 0.5" wc to 6 psig [12.7 mm wc to 0.4 barg]

RA Operation
For small flow requirements, the pilot can be used by itself as a direct spring tank blanketing valve. When used this way, it is designated a Type RA. The only difference in construction is the location of the sense and inlet ports. The sensed pressure acting against the spring force will determine how much, if any, the pilot is to open.

Y1 Operation
Upstream pressure enters the main body and acts upward against the main valve diaphragm. Due to a small unbalanced dome area, the effective area above the diaphragm is slightly larger than below. Shut-off will occur when the dome pressure is equal to the inlet pressure. The sleeve/diaphragm retainer assembly is lightly spring loaded to provide initial closing force when there is no pressure differential across the diaphragm.

The Type Y1 Pilot controls dome pressure in response to tank pressure. A reduction in dome pressure allows the sleeve to move upward off the main seat, permitting flow through the valve. The amount of lift depends on the pressure reduction in the dome. The greater this reduction, the greater the flow. When the downstream pressure is satisfied, the sensed pressure acting on the pilot sense plate will overcome the spring force to close the pilot, which in turn closes the valve. No system fluid is vented to the atmosphere.

BV-1 Operation
The diaphragm and sleeve are replaced by a piston in the main valve for more rugged construction. As with the Y1 Valve, the pilot controls dome pressure. A reduction in dome pressure allows the piston to move horizontally off the seat, permitting flow through the valve. Maximum flow is controlled by the cage orifices.