For low pressure steam and hot water boilers larger than 5,000 sq. ft. (465m2) capacity with cold water feed
Quick-change replaceable cartridge valve and strainer
Optional Features
No. 2 switch
Manual reset
Float block
Proportional feed action
Model 51 can be field upgraded with a No. 2 switch to add low water cut-off function
Maximum water supply pressure 150 psi (10.5 kg/cm2)
Maximum inlet water temperature 120°F (49°C)
Maximum vessel pressure 35 psi (2.5 kg/cm2)