Series 251/253/254 Welded Chamber Level Control

External Mount Pressure to 1250 psig, Hermetically Sealed Switches, Temperature to 750°F, Explosion-Proof Housings

Time proven magnetic head leak proof construction combines with a heavy duty welded chamber to provide excellent reliability for control of compatible liquids. Operating pressures of 1250 psig (86 bar) at 650°F (345°C) and 750 psig (52 bar) at 750°F (400°C) are standard. 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. The controls feature carbon steel bodies and stainless steel internal trim. Process mounting configurations include either side/bottom combination 1" NPT/socket weld hubs, side/bottom flanges or side/side flanges. A variety of hermetically sealed snap action or mercury switches are available in SPST, SPDT, or DPDT action for single or two stage operation. Mercury or Gold alloy snap action contacts are suitable for low current DC applications. A full range of switch enclosures are offered. Many chamber, enclosure and switch combinations are UL approved.

Product Applications

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

Models & Ordering

Build Your Custom Part. Use our Product Configurator

Specifications

C1-75:
Minimum specific gravity 0.75. Process pressure 1250 psig (86 bar) at 100°F (38°C), to 650°F (345°C). 750 psig (52 bar) at 750°F (400°C).*
*Heat fins and/or high temperature switches should be considered for process temperatures above 500°F (260°C).
Temperature Limit:
Ambient Temperature: 212°F (100°C); Process Temperature: 750°F (400°C).*
*Heat fins and/or high temperature switches must be used for process temperatures above 500°F (260°C).
Switch Types:
Snap action or mercury.
Electrical Rating:
See Model Chart.
Wiring Connections:
G, WT or E enclosure, terminal block. EV enclosure 189 (460 mm) leads.
Process Connections:
Combination 1" NPT/socket weld hubs or flanges. See model chart.
Wetted Parts:
C1 construction, carbon steel, 303SS, 304SS, 316SS, 430SS. (Optional 316SS with 430SS).
Enclosures:
G painted steel and aluminum. WT, painted steel, aluminum and neoprene. E, aluminum. EV, aluminum, neoprene.
Weight:
251: 40 lb (18 kg); 253: 50 lb (22.7 kg); 254: 57 lb (25.8 kg).
Suggested Specifications:
Liquid level control shall be 251 (253) (254) Series with combination 1" NPT/socket weld hubs (flanged) process connections. Chamber shall be welded carbon steel (316SS) suitable for operation at 1250 psig (86 bar) at 100°F (38°C) to 650°F (345°C), 750 psig (52 bar) at 750°F (400°C) at a minimum specific gravity of 0.75. Circuit shall be (hermetically sealed) snap action (mercury) switch (SPST) (SPDT) (DPDT). Enclosure shall be general purpose (weather proof) (explosion-proof) (explosion-proof – vapor proof). Switch mechanism shall be gravity return and shall be activated by a stainless steel float.

Model Chart

  
EXAMPLE 251 WT 7810 C1 60   251-WT-7810-C1-60 Liquid Level Control, welded carbon steel chamber, weatherproof enclosure, SPDT snap switch, fixed deadband, automatic reset, operating pressure 350 psig (24 bar) at 100°F (38°C), 300 psig (21 bar) at 600°F (315400°C), side/bottom 1" NPT, minimum specific gravity 0.60.
CONNECTION 251           One Vertical and One Horizontal 1" NPT
253           One Vertical and One Horizontal Flanged Connection
254           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
CIRCUITS
(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
    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
      HFC1     Heat Fins, Carbon Steel Body
      C216     316SS Body
      HFC216     Heat Fins, 316SS Body (251 only)
      C217     316SS Housing with Shield (251 only)
MINIMUM
SPECIFIC
GRAVITY
        60   0.60 Specific Gravity (251 only)
        75   0.75 Specific Gravity (251 only)
        160   0.60 Specific Gravity & 150# Flange (253, 254 only)
        175   0.75 Specific Gravity & 150# Flange (253, 254 only)
        360   0.60 Specific Gravity & 300# Flange (253, 254 only)
        375   0.75 Specific Gravity & 300# Flange (253, 254 only)
        660   0.60 Specific Gravity & 600# Flange (253, 254 only)
        675   0.75 Specific Gravity & 600# Flange (253, 254 only)
OPTIONS           R Manual Reset, Single Stage
          R1 Manual Reset, Lower Stage of 2-Stage Controls
          R2 Manual Reset, Upper Stage of 2-Stage Controls
          R3 Manual Reset, Both Stages of 2-Stage Controls
          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



CHARTS A & B - ELECTRICAL CIRCUITS AND RATINGS

 

SWITCH TYPE
SWITCH ACTION
ELECTRICAL RATINGS IN AMPS
ORDERING CODE
AC
DC
SINGLE STAGE
TWO STAGE
120V
240V
440V
30V
125V
250V
LOWER
UPPER
CHART A
Mercury Contacts
SP-ST open on level FALL
10
5
3†
 
10
5
-4821
-4821
-21
SP-ST open on level RISE
10
5
3†
 
10
5
-4820
-4820
-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
-4813
-4813
-13
DP-ST two switches E.I.* open on level RISE
10
5
3†
 
10
5
-4814
-4814
-14
DP-DT two SP-DT switches
4
2
1†
 
4
2
-4806
-4806
-06
CHART B
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
DP-DT Two SP-DT switches
2
2
 
 
0.4**
0.25**
-1006
-1006
-06
SP-DT one switch
2
2
 
 
0.4**
0.25**
-1010
-1010
-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.
**Resistive.

Product Literature

Manuals

Catalog Pages

SDS

Approvals

Drawings

Questions

Question
Why is the minimum specific gravity important on the float level switches?
Answer
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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