Series 1251/1253/1254 Welded Chamber Level Control

Min. Specific Gravity 0.40, Pressure to 1250 psig (86 bar), and Temperature to 500°F (260°C)

Leak proof all welded heavy duty carbon steel bodies coupled with snap action or mercury switches provide reliable, long term service for compatible liquids. The use of an external magnet reduces the possibility of magnetic particle build-up inside the armature tube and subsequent loss of operation as may occur with the internal magnet repulsion design. A variety of snap action or mercury switches in SPST, SPDT, DPDT or DPST configurations will satisfy most electrical requirements. These switch assemblies are contained in NEMA 1 general purpose, NEMA 4X weatherproof, NEMA 7, 9 groups B, C, D, E, F, G, explosion-proof or explosion-proof – vapor proof enclosures.

Product Applications

  • Refineries
  • Chemical Plants
  • Power Generating Stations
  • Water Treatment Plants
  • Mixing Systems
  • Scrubbers
  • Accumulators
  • Condensate Recovery
  • Industrial Tanks and Vessels

Models & Ordering

Shipping Information

All shipping times are dependent on product availability at time of shipment.

Although we make every effort to ensure a continuous supply of our products, occasional circumstances may force us to temporarily run out of a product, or have shipping delays. Should this occur, customers will be notified soon after placement of any orders for such products and, if applicable, items will be put on backorder. For orders requiring expedited shipment, our customer service team can be contacted to confirm product availability

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Minimum specific gravity 0.40. Process pressure 1250 psi (86 bar) at 100°F (38°C) to 500°F (260°C).
Temperature Limit:
Ambient Temperature: 212°F (100°C); Process Temperature: up to 500°F (260°C).
Switch Type:
Snap action or mercury. See Model Chart.
Electrical Rating:
See Model Chart.
Wiring Connections:
G, WT or E enclosure: terminal block; EV enclosure: 18" (460 mm) leads.
Process Connection:
Combination 1" NPT/socket weld hubs or flanges. See Model Chart.
G: painted steel and aluminum; WT: painted steel, aluminum and neoprene; E: aluminum; EV: aluminum and neoprene.
Wetted Parts:
C1 construction. Chamber: carbon steel; Trim: 303SS, 304SS, 316SS and 430SS.
1251: 40 lb (18 kg); 1253: 50 lb (22.7 kg); 1254: 57 lb (25.8 kg).
Suggested Specifications:
Liquid level control shall be 1251 (1253) (1254) Series with 1" combination NPT/socket weld hub (flanged) process connections. Chamber shall be welded and suitable for operation at 1250 psig (86 bar) and 500°F (260°C) with a minimum specific gravity of 0.40. Circuit shall be hermetically sealed snap action (mercury) switch (SPST) (SPDT) (DPDT). Enclosure shall be general purpose, (explosion- proof) (explosion-proof – vapor proof). Switch mechanism shall be gravity return and shall be activated by a stainless steel float.

Model Chart

EXAMPLE 1251 WT 7810 C1 40   1251-WT-7810-C1-40 Liquid Level Control, weatherproof enclosure, SPDT snap switch, fixed deadband, automatic reset, operating pressure 1250 psig (86 bar) at 100°F (38°C), 1250 psig (86 bar) at 500°F (260°C), side/bottom process connections, 1" NPT/socket weld hubs, minimum specific gravity 0.40.
CONNECTION 1251           One Horizontal and One Vertical 1" Socket Weld or 1" NPT Combination Hub
1253           One Vertical and One Horizontal Flanged Connection
1254           Two Vertical Flanged Connections
ENCLOSURE    G         General Purpose, NEMA 1
  WT         Weatherproof, NEMA 3R, 4, 4X
  E         Explosion-proof, NEMA 7, 9, Class I Groups B, C, D, Class II Groups E, F, G
  EV         Explosion-proof/Vapor-proof, NEMA 7, 9, Class I Groups B, C, D, Class II Groups E, F, G
(for electrical circuits
see charts A & B below)
    48XX       Single Stage Mercury Switch, see chart A
    48XX-XX       Two Stage, Mercury Switch, see chart A
    78XX       Single Stage, Snap Switch, see chart B
    78XX-XX       Two Stage, Snap Switch, see chart B
    78XXHM       Hermetically Sealed Snap Switch, see chart B
    98XX       Single Stage, High Capacity DC Snap Switch, use heat fins (HF) if process temperature exceeds 350°F (177°C), do not exceed 450°F (232°C), see chart B
    98XX-XX       Two Stage, High Capacity DC Snap Switch, use heat fins (HF) if process temperature exceeds 350°F (177°C), do not exceed 450°F (232°C), see chart B
CHAMBER MATERIAL       C1     Carbon Steel Body
      C216     316SS Body
      HFC1     Heat Fins & Carbon Steel Body
      HFC216     Heat Fins & 316SS Body (1251, 1253 only)
        40   0.40 Specific Gravity (1251 only)
        140   0.40 Specific Gravity & 150# Flange (1253, 1254 only)
        340   0.40 Specific Gravity & 300# Flange (1253, 1254 only)
        640   0.40 Specific Gravity & 600# Flange (1253, 1254 only)
OPTIONS           STW SS Tag Wired
          01 Breather Only (E-Housing only)
          02 Drain Only (E-Housing only)
          12 Breather & Drain (E-Housing only)
          23720 Fungus Proofing

120V 240V 440V 30V 125V 250V LOWER UPPER
Mercury Contacts
SP-ST open on level FALL 10 5 3†   10 5 -4820 -4820 -21
SP-ST open on level RISE 10 5 3†   10 5 -4821 -4821 -20
SP-DT one switch 4 2 1†   4 2 -4810 -4810 -10
SP-DT two switches E.I.* 10 5 3†   10 5 -4815 -4815 -15
DP-ST two switches E.I.* open on level FALL 10 5 3†   10 5 -4814 -4814 -13
DP-ST two switches E.I.* open on level RISE 10 5 3†   10 5 -4813 -4813 -14
DP-DT two SP-DT switches 4 2 1†   4 2 -4806 -4806 -06
snap action contacts
SP-DT one switch 12 5 3†   0.5** 0.25** -7810 -7810 -10
DP-DT two SP-DT switches 12 5 3†   0.5** 0.25** -7806 -7806 -06
SP-DT one hermetically sealed switch 5 5   5**     -7810HM -7810HM -10HM
DP-DT two hermetically sealed SP-DT switches 5 5   5**     -7806HM -7806HM -06HM
DP-DT two SP-DT switches 10 3     10‡ 3‡ -9806 -9806 -06
SP-DT one switch 10 3     10‡ 3‡ -9810 -9810 -10
†Available on special order, change 1st digit in ordering code from 4 to 5 or 7 to 8, i.e., -4820 becomes -5820, -7810 becomes -8810, etc.
‡10 amp inductive (polarized) at 125 VDC.
*Electrically Independent.

Product Literature


Catalog Pages





Why is the minimum specific gravity important on the float level switches?
If a medium has a lower s.g. than the rated minimum for a float, the float will sink through the media and the switch will not operate.

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