Series-391-393-394

The Series 391-393-394 range of level controls are engineered for rugged industrial service - ideal for refineries, petrochemical plants, power generation stations and other harsh-environment vessels. With side-mounted float chamber construction, these units offer high pressure and temperature capability (up to approximately 650 psig and 600 °F) and a selection of robust materials including carbon steel body (standard) and stainless-steel wetted parts for extended service life.

The core mechanism features stainless-steel float and switching assemblies, using gravity-return action rather than springs, which enhances reliability in cyclic and high-shock installations. A welded chamber design ensures integrity under pressure, while the enclosure options (weather-proof NEMA 4X, explosion-proof Class I/II) provide flexibility for indoor or hazardous-location installations.

Connections vary by model: the 391 version typically employs 1″ NPT side/bottom ports, while the 393-394 models extend to flange connection options (150#, 300#, 600#) for heavier process systems. Minimum fluid specific gravity options down to 0.70 (or 0.80/0.95 depending on flange rating) allow use with lighter hydrocarbons or condensate systems. 

Switching outputs include SPDT snap switches, hermetically sealed snap switches or mercury switch options, with electrical enclosures suitable for general-purpose, weather-tight or explosion-proof service, depending on model. 

The Series-391-393-394 side-mounted chamber level controls are a high-integrity, durable solution for level detection in process vessels where high pressure, high temperature, tough fluids and severe service are the norm - offering configurable options for connection type, enclosure rating, specific gravity and switch form.