AMOT Model 4121 Vibro-Guard Valve is a 2-way acceleration sensing valve with optional electric microswitch. It is closed under normal conditions and trips open to vent when vibration or shock exceeds the set level. This venting action, when used in a pneumatic safety control system, can be used to sound a pneumatic alarm or shut down malfunctioning equipment, or both. Failing bearings, broken blades, cracked, broken or bent shafts, misfiring, and accumulated deposits are a few of the items which the Vibro-Guard can detect.
The unit is available with an optional microswitch for applications where an electrical signal is desired. The valve may be reset manually or by means of a pneumatic cylinder in the cover. The pneumatic reset feature is also used as a starting or time-delay lockout when desired for machinery which vibrates heavily during start up. Since the standard unit is non-electric, it can be used in hazardous locations without an explosion-proof housing. This unit is weatherproof and anodized for corrosion protection in salt spray atmospheres (Gulfproofed).
The Model 4121 trip point is easily adjusted to the desired level of sensitivity after installation and is highly repeatable once set.
The 4121 vibration switch makes use of a pivoted level assembly with a high strength, potted-type magnet near the end opposite the pivot. When the unit is reset, the magnet is thrust toward the steel armature embedded in the base and is held there by magnetic force plus the force of the loading spring until the inertia of the lever assembly upon increasing velocity or shock (acceleration) exceeds the holding force of the magnet and spring. When this occurs, the lever assembly snaps to the tripped position and remains there until intentionally reset. Tripping of the lever assembly moves the plunger of the snap switch and causes it to operate. Easy changes in adjustment are made by removing the cover and turning adjusting wheel which changes the spring bias.