Mercoid Series 1221

High-Pressure Float Level Control — Boiler & Steam Drum Service

Rated to 900 psig — 525°F — ASME Code Construction Available

The Mercoid Series 1221 is designed specifically for boiler and steam drum level control at elevated pressures and temperatures. Rated to 900 psig at 525°F, the Series 1221 features heavy-duty chamber construction with stainless steel wetted parts and ASME code construction available for power plant and industrial boiler applications. The reliable SPDT snap switch provides dependable switching for boiler feed pump control and high/low water alarms. The Series 1221 bridges the gap between the Series 1211 and the extreme-service Series 1261, making it the most widely specified Mercoid boiler-service float switch.

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Specifications

Service

Steam drum and high-pressure boiler service.

Wetted Materials

Body: carbon steel or alloy steel; Float and Trim: 304/316 stainless steel.

Temperature Limit

525°F (274°C).

Pressure Limit

900 psig (62 bar).

Enclosure Rating

NEMA 4X standard. Optional explosion-proof.

Switch Type

SPDT snap switch. Optional DPDT or two-stage.

Electrical Rating (Snap)

12A @ 120 VAC, 5A @ 240 VAC, 0.5A @ 125 VDC, 0.25A @ 250 VDC resistive.

Electrical Connections

Screw terminal.

Conduit Connection

3/4″ female NPT.

Process Connection

1″ female NPT or flanged. Optional socket weld.

ASME Construction

Available on request for code-stamped applications.

Specific Gravity

0.7 minimum.

Agency Approvals

UL.

Popular Models

Model Number	Description
1221-WT-7810-C-60	Boiler service float level control, SPDT snap switch, 900 psig.
1221-WT-7810-C-60-ASME	ASME code construction, boiler service, SPDT snap switch.

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