Honeywell Discontinued: Valve proving system A4021
Kromschroeder alternatives for A4021/A8041 Valve Proofing System. Replaces both the control unit and gas pressure switch. Only needs extra tube connection upstream the first valve.

Functional replacement for A8021A1003 (24Vdc). Replaces the gas pressure switch that monitors the pressure between valve 1 and 2. Additional tube is needed to measure the pressure upstream of the first valve.