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.