Page 2 - ORDERING INFORMATION
L91A,B,D PROPORTIONING PRESSURETROL ® CONTROLLERS 60-2152—08 2 ORDERING INFORMATION When purchasing replacement and modernization products from your TRADELINE® wholesaler or distributor, refer to the TRADELINE® Catalog or price sheets for complete ordering number. If you have additional questions, n...
Page 5 - INSTALLATION; WARNING; Location and Mounting; Mounting Beside a Pressure Gauge
L91A,B,D PROPORTIONING PRESSURETROL ® CONTROLLERS 5 60-2152—08 INSTALLATION When Installing This Product... 1. Read these instructions carefully. Failure to follow them could damage the product or cause a hazardous condition. 2. Check the ratings given in the instructions and on the product to make ...
Page 6 - WIRING; Setting
L91A,B,D PROPORTIONING PRESSURETROL ® CONTROLLERS 60-2152—08 6 Fig. 3. L91 terminal blocks and internal schematics. WIRING 1. Disconnect power supply before beginning installation to prevent electric shock and equipment damage. All wiring must comply with applicable electrical codes, ordinances, and...
Page 7 - Typical Operation
L91A,B,D PROPORTIONING PRESSURETROL ® CONTROLLERS 7 60-2152—08 point). The L91B settings provide system modulation between 70 and 75 psi or between 75 and 80 psi, depending on the exact setting of the L91B main scale setpoint. Due to device tolerances, the scaleplate settings are approximate and, th...
Page 8 - CHECKOUT; CAUTION
L91A,B,D PROPORTIONING PRESSURETROL ® CONTROLLERS 60-2152—08 8 CHECKOUT After the controller is installed, wired, and set, it should be tested with the system in operation. First, allow the system to stabilize. Then, observe the operation of the controller while raising and lowering its setpoint. Pr...
Page 9 - SERVICE INFORMATION; Calibration
L91A,B,D PROPORTIONING PRESSURETROL ® CONTROLLERS 9 60-2152—08 SERVICE INFORMATION CAUTION Electrical Shock Hazard 1. Only qualified service technicians should attempt to service or repair flame safeguard controls and burner systems. 2. Disconnect power supply before cleaning the potentiometer windi...