Q. In your catalog you have two manual reset pressure switches for duct application, the 1900-5-MR and the AFS-460. What is the difference in these two switches?

A. The 1900-5-MR monitors static pressure in the duct and makes a SPDT switch when excess pressure occurs. It is designed primarily to prevent duct blowout, and includes 18" of tubing, an A-345 mounting flange, and two A-339 adapters. The 1900-5-MR is for sensing positive static pressure only, not differential pressure.

The AFS-460 measures differential pressure as well as static pressure. In addition to monitoring excess static pressure in the duct, it may also be used to detect dirty filters, frozen coils, and damper status.