Series-123-125

Supported Applications

The Dwyer Series 123 and 125 Boiler Water Level Controls are designed for boiler applications, specifically serving as low water cut-off or feed-water control devices. The series is also utilized in condensate tanks and deaerators.

Operating Conditions & Performance

The Series 123/125 operates with a process temperature limit of 365°F (185°C) and an ambient temperature limit of 212°F (100°C). The pressure rating is 150 psig (10.34 bar), suitable for compatible liquids; the cast iron body is not approved for use with lethal or flammable substances, either liquid or gaseous.

Performance characteristics include a deadband of approximately 1-1/2" (38.1 mm) and a minimum specific gravity requirement of 0.88. The unit requires vertical mounting orientation.

Configuration Options

The series offers configurable switch mechanisms, enclosure ratings, and reset options to meet different control needs:

• Switch Types: SPDT snap action or mercury switch (direct action). Optional DPDT or two-stage configurations are available.
• Enclosure Ratings: General purpose standard; optional weatherproof enclosure.
• Options: Manual reset capability is offered as an option.

The unit features a flanged chamber design that allows for easy clean-out and replacement of the float or switch mechanism without removing the control from the piping. A transparent cover provides visible operation of the internal mechanism.

Key Product Differences

Differences between models are defined by the specific switch technology employed:

• Model 123-153: Equipped with an SPDT mercury switch, providing a close deadband.
• Model 123-7000-153: Features an SPDT snap action switch mechanism designed to eliminate frequent operation due to surging water levels.

Electrical ratings vary by switch type. The snap switch is rated at 12 A @ 120 VAC, 5 A @ 240 VAC, 0.5 A @ 125 VDC resistive, and 0.25 A @ 250 VDC resistive; it is not UL-rated for compliance. The mercury switch is rated at 4 A @ 120 VAC/DC and 2 A @ 240 VAC/DC.

Wetted materials include a cast iron body, 304 SS float, brass trim and packing gland, carbon packing, and a carbon body gasket. Electrical connections are made via screw terminals with a conduit connection hole of 7/8" (22.23 mm) for 1/2" (12.7 mm) conduit.