The Model 461-57S and Model 441-57S are spring-operated regulators that incorporate a “roll-out” diaphragm which approximates the performance of a pilot-operated regulator. The roll-out diaphragm makes this exceptional performance possible because its action reduces “droop” to a minimum. By offering near pilot-operated performance without a pilot, the 57S regulators offer the advantages of simplicity, dependability, freedom from freeze-up, and exceptionally fast response.
Both models are perfect for most intermediate and large capacity applications including gas distribution systems, district regulator sets, city gate stations, town border stations, monitoring, and a wide variety of industrial applications. These workhorses of the industry have provided dependable service for over 60 years.