Spring-Loaded Pressure Relief Valves are the last resort when abnormal pressure conditions endanger the silo structure. This is why sudden excess or suction pressure inside the silo must be dealt with instantaneously. Even though ideally a Pressure Relief Valve should never have to go into action, it must be efficient and reliable if needed. With hundreds of thousands installed worldwide, Spring-Loaded Pressure Relief Valves have given evidence of being totally reliable under most different conditions. For applications in the food industry a version compliant with European Regulation (EC) No. 1935/2004 is available. Spring-Loaded Pressure Relief Valves consist of a cylindrical casing with a bottom flange to be connected with a spigot welded on the silo roof, a disc shape inner steel lid for negative pressure operation held in position by a central spring rod, an outside steel ring for excess pressure kept in position by three spring rods, gaskets, and a weather protection cover.
Function
Helical springs keep the valve lids closed when the pressure value remains within the preset limits. The three outside spring rods keep the external ring-shaped lid firmly closed as long as the force generated by the pressure inside the silo does not overcome the spring force. Once the pressure exceeds the pre-set value the lid is pushed up and pressure can escape. The smaller lid covers the central circular opening of the external lid from below. It is held in the middle by a single spring rod and is pressed onto the external lid by the normal air pressure inside the silo. In the event of suction pressure the spring is compressed and allows the lid to drop. The air entering the silo from outside ensures rapid pressure balance and pushes the central lid back up into "closed" position.
For applications in the food industry a version compliant with European Regulation (EC) No. 1935/2004 is available.
Features
Two sizes available
Flow rate: up to 13,000 m3/h (7,650 cfm)
Painted carbon steel or 304 stainless steel casing
Stainless steel weather protection cover
Mechanical set-up for inductive signalling sensor
Preset for maximum negative pressure of -0.005 bar (-0.07 psi) and maximum excess pressure of 0.05 bar (0.72 psi)
Benefits
Lightweight design and reduced overall dimensions for extremely comfortable handling
Easy to fit
Quick maintenance
Options
ATEX certified version
Compliance with European Regulation (EC) No. 1935/2004
Optionally different settings available
Inspection hatch
Inductive sensors
Bird net
