Mercoid, DA-31-156-3, Series DA Bourdon Tube Pressure Switch, -4.91 - 12 psigSeries DA Bourdon Tube Pressure Switch, Mercury Switch Tilt Type (Std), Brass, Standard with Bottom Connection, 9-51 NO, SPST & 9-51 NC, SPST, -4.91 - 12 psigThe Mercoid D Series is one of the world's broadest lines of pressure switches. Whatever your application might be, it is most probable it can be fully satisfied with a D Series pressure switch.The D Series has extremely high sensitivity and great repeatability. The DA Models are equipped with two external adjustments, one for setting high pressure operating point, the other for setting low pressure operating point. Deadband, the difference between high and low set points, is adjustable over the full scale. The DS Models are equipped with a single external adjustment for setting operating point only. The deadband is fixed at a factory setting and cannot be altered in the field. For switches choose between the snap action switch, hermetically sealed snap action switch and hermetically sealed mercury switch.FeaturesVisible calibrated dial.On/off indication (except hermetically sealed snap switch models).Adjustable or fixed deadband.SPDT snap-action, hermetically sealed snap action or hermetically sealed mercury switch.External switch setpoint adjustments.Minimum deadband is obtainable at any point in the range.Pressure Ranges of full vacuum to 8000 psig.UL listed, CSA approved. Many models FM approved.General purpose, weatherproof or explosion-proof enclosures.ApprovalsCSA-Comfort Conditioning EquipmentCSA Approval-Misc ApparatusCSA Approval-Motor ControllersUL-Controllers, Refrigeration-USUL-Controls, Limit-USUL-Motor Controllers-USUL-Motor Controllers-Hazardous Locations-USUL-Switches-US.