Series-1261-1263-1264Configuration

Supported Applications

The Dwyer Series 1261, 1263, and 1264 are liquid level controls designed for high-pressure service in oil and chemical plants. These units feature a heavy-duty welded carbon steel chamber capable of operating up to 1750 psig (121 bar) at 100°F (38°C). The series is engineered for liquids with a minimum specific gravity of 0.60, utilizing hermetically sealed snap-action or mercury switches within the switch mechanism.

Operating Conditions & Performance

The Series 1261-1264 operates under demanding process conditions, supporting temperatures up to 500°F (260°C). Pressure ratings vary by temperature: 1750 psig (121 bar) at 100°F (38°C), and 1650 psig (114 bar) at 500°F (260°C). The series offers a repeatability of ±1/4" (6.4 mm).

Switch operation is non-adjustable, with level changes dependent on specific gravity:

• Single Stage Operation: At 1.0 Sp Gr., the change is 5-1/2" (140 mm) for parameter A and 7/8" (22 mm) for B; at 0.6 Sp Gr., it is 6" (152.4 mm) for A and 1-1/8" (29 mm) for B.
• Two Stage Operation: At 1.0 Sp Gr., parameters include 5-1/2" (140 mm), 7/8" (22 mm), 6-1/4" (159 mm), 7/8" (22 mm), and 3/4" (19 mm); at 0.6 Sp Gr., values shift to 6" (152.4 mm), 1-1/8" (29 mm), 6-7/8" (175 mm), 1-1/8" (28.6 mm), and 7/8" (22 mm).

Electrical ratings for mercury contacts include up to 10 Amps at AC 120V, while snap-action contacts support up to 12 Amps at AC 120V. High capacity DC options are available with specific heat fin requirements if process temperature exceeds 350°F (177°C).

Configuration Options

The series is configurable across multiple dimensions including enclosure type, circuit arrangement, and chamber construction.

• Enclosures: Available in General Purpose (G) NEMA-1; Weather Proof (WT) NEMA-3R, 4, 4X; Explosion-proof (E) NEMA-7, 9 Class I Groups B, C, D and Class II Groups E, F, G; and Explosion-proof Vapor-proof (EV).
• Switch Types: Options include Mercury Contacts (-48XX series) for single or two-stage operation, Snap Action Contacts (-78XX series), Hermetically Sealed Snap Switches (-78XXHM), and High Capacity DC Snap Switches (-98XX series).
• Circuit Arrangements: Configurable as SPST, SPDT, DPDT, or DPST. Two-stage operation is available for both mercury and snap-action types.

Key Product Differences

The series distinguishes itself through three primary model families based on process connection geometry:

• Type 1261: Features a welded carbon steel body with side/bottom process connections using combination 1" NPT/socket weld hubs. Rated for 1750 psig (121 bar) at 100°F and 1650 psig (114 bar) at 500°F.
• Type 1263: Equipped with 1" 600# flanges for side/bottom process connections. Rated for 1450 psi (99 bar) at 100°F and 1232 psi (84 bar) at 500°F.
• Type 1264: Equipped with 1" 600# flanges for side/side process connections. Rated for 1450 psi (99 bar) at 100°F and 1232 psi (84 bar) at 500°F.

Wetted materials include carbon steel, 303SS, 304SS, and 430SS. An optional breather and drain is available for E type enclosures, recommended for high humidity or outdoor service.