L91D Proportioning Pressuretrol Controller
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L91A, B, D Proportioning Pressuretrol Controllers
L91 Proportioning Pressuretrol® Controllers are Series 90 Modulating Pressure Controllers that provide direct control of modulating motors or valves used on automatic burners or steam heating systems.
• Models available for pressure systems up to 300 psi (2068 kPa).
• May be used with steam, air, noncombustible gases, or other fluids noncorrosive to brass or phos-bronze (300 psi model) bellows.
• When used with steam boilers, a steam trap (siphon loop) is recommended.
• Wiper on controller potentiometer moves in response to pressure changes.
• L91D has two potentiometers for unison control of two motors.
• L91B,D models have adjustable proportioning (throttling) range to allow selection of desired pressure control range.
• Adjustments made with screws on case top.
• Large, easily-read scale plates in both U.S. customary (oz/sq. in., psi, or in. Hg) and metric (kPa, MPa, or mm Hg) units.
• Steel case with clear plastic cover to observe pressure settings and potentiometer action.
• Fitting with 1/4 -18 NPT threads allows rapid installation.
• Surface mount with screws through knockout holes in case back.
Replaces Part Number: L91D1015