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Hi-limit DUAL Contact Differential Pressure Switch

2009 June 19
by admin; 3,153 views

The Dwyer folks stopped by our offices Monday to show us some exciting new products that will be available next month.  One of the products we found particularly fascinating was a unique hi-limit differential pressure switch.  An AHU with a variable speed fan has a differential pressure sensor located two-thirds of the way down the duct.  This sensor measures the differential pressure and controls the speed of the fan to maintain a specific set-point (usually in inches of water column).  Somewhere in the fan discharge is usually a hi-limit differential pressure switch that is used to shut-down the fan and alarm the DDC system when there is an over pressure situation.  

Dwyer has designed a hi-limit switch that does not require power, and has 2 sets of contacts to both shut-down the fan, and alarm the DDC system. The contacts are opened by the physical movement of the diaphragm, therefore no power wiring is required. Because the unit has (2) sets of contacts, a separate relay and additional wiring is avoided.  The product is commercial quality, made of metal (not plastic), and has barbed connections for tubing.  We will be showcasing the product in the "Product Solutions" section on our website as soon as it is available. 

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