The SD-SVS OSY Series is used to monitor the open position of an OS&Y (outside screw and yoke) type gate valve. This device is available in three models; the SD-SVS OSY-1, containing one set of SPDT contacts, the SD-SVS OSY-2, containing two sets of SPDT contacts and the SD-SVS OSY-3, containing two sets of SPDT and cover tamper. These switches mount conveniently to most OS&Y valves ranging in size from 2” to 12” (50mm to 300mm). They will mount on some valves as small as ½” (12.5mm). Supervisory Switch shall be installed on each valve as designated on the drawings and/or as specified herein. Switches shall be mounted so as not to interfere with the normal operation of the valve and shall be adjusted to operate within two revolutions of the valve control or when the stem has moved no more than one-fifth of the distance from its normal position. The mechanism shall be contained in a die cast metal housing that provides a side entrance for ½” conduit and incorporates the necessary facilities for attachment to the valve. A grounding provision is provided. The switch assembly shall include two switches each with a rated capacity of 10 Amp @ 125/250VAC and 2.5 Amp @ 24 VDC. The supervisory switch shall be Underwriters La boratories listed for indoor or outdoor use.