Series 391/393/394 Side Mounted-Chamber Type Level Control

Compact, Low Cost, Hermetically Sealed Snap Switch Option

Heavy duty and low cost is the perfect description for the 391 Series level control. Stainless steel switching mechanism uses gravity return action instead of springs for long life. Weatherproof enclosure is standard. Welded steel chamber is good for 650 psig (45 bar) at 600°F (315°C).

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

Service:
Compatible liquids.
Wetted Materials:
Body: carbon steel; Float and Trim: 303 SS, 304 SS, 316 SS, and 430 SS.
Temperature Limits:
Ambient Temperature: 212°F (100°C); Process Temperature: up to 600°F (315.6°C)*.
*Heat fins and/or high temperature switches must be used for process temperatures above 500°F (260°C) with mercury switches, 400°F (204°C) with snap switches, and 350°F (176.7°C) with hermetically sealed snap switches.
Pressure Limits:
800 psig (55 bar) at 100°F (37.7°C), 650 psig (45 bar) at 600°F (315.6°C). Higher ratings available.
Enclosure Rating:
NEMA 4X. Optional general purpose or explosion-proof.
Switch Type:
SPDT snap switch, hermetically sealed snap switch or mercury switch. Optional DPDT.
Electrical Rating:
Snap Switch: 12A @ 120 VAC, 5A @ 240 VAC, 0.5A @ 125 VDC resistive, 0.25A @ 250 VDC resistive. Hermetically Sealed Snap Switch: 5A @ 125 VAC, 5A @ 240 VAC, 5A @ 30 VDC resistive. Mercury Switch: 4A @ 120 VAC/DC, 2A @ 240 VAC/DC. Higher contact ratings available for the mercury switch.
Electrical Connections:
Screw terminal.
Conduit Connection:
3/4" female NPT.
Connections:
1" female NPT. Optional 1" socket weld hub or flange connections.
Mounting Orientation:
Vertical.
Weight:
10 lb (4.5 kg).
Agency Approvals:
UL, none on HM switch.
Specific Gravity:
0.8 minimum. Optional 0.7 minimum.

Model Chart

 
EXAMPLE 391 WT 7810 C1 70   391-WT-7810-C1-70 Liquid Level Control with welded carbon steel chamber, watertight – NEMA 4X enclosure, SPDT snap action switch rated 12 amp 120 VAC, 5 amp 240 VAC, fixed deadband and automatic reset, operating pressure 600 psig (41 bar) at 100ºF (38ºC), 500 psi (34 bar) at 600ºF (315ºC), side/bottom process connections 1” NPT, minimum specific gravity 0.70.
CONNECTION 391           One Horizontal and One Vertical 1” NPT or Socket Weld
393           One Vertical and One Horizontal Flanged Connection
394           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       Two stage, mercury switch, see chart A.
    78XX       Single stage, snap switch, see chart B.
    78XX       Two stage, snap switch, see chart B.
    78XXHM       Hermetically sealed snap switch, see chart B.
    98XX       Single stage, high capacity DC snap switch, see chart B.
    98XX       Two stage, high capacity DC snap switch, see chart B.
    10XX       Single stage, high temperature snap switch, see chart B.
    10XX       Two stage, high temperature snap switch, see chart B.
CHAMBER MATERIAL             Refer to chart C below for pressure/temperature ratings
      C1     Carbon steel body
MINIMUM SPECIFIC
GRAVITY
        70   0.70 specific gravity (391 only)
        80   0.80 specific gravity (391 only)
        95   0.95 specific gravity (391 only)
        170   0.70 specific gravity & 150# flange (393, 394 only)
        180   0.80 specific gravity & 150# flange (393, 394 only)
        195   0.95 specific gravity & 150# flange (393, 394 only)
        370   0.70 specific gravity & 300# flange (393, 394 only)
        380   0.80 specific gravity & 300# flange (393, 394 only)
        395   0.95 specific gravity & 300# flange (393, 394 only)
        670   0.70 specific gravity & 600# flange (393, 394 only)
        680   0.80 specific gravity & 600# flange (393, 394 only)
        695   0.95 specific gravity & 600# flange (393, 394 only)
OPTIONS           H2 1” socket weld hub instead of 1” NPT
          STW SS tag wired
          01 Breather only (E-Housing only)
          02 Drain only (E-Housing only)
          12 Breather and drain (E-Housing only)
          23720 Fungus proofing special 23720
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
UL
SP-ST open on level RISE
10
5
3†
 
10
5
-4820
-4820
-20
UL
SP-DT one switch
4
2
1†
 
4
2
-4810
-4810
-10
UL
SP-DT two switches E.I.*
10
5
3†
 
10
5
-4815
-4815
-15
UL
DP-ST two switches E.I.* open on level FALL
10
5
3†
 
10
5
-4813
-4813
-13
UL
DP-ST two switches E.I.* open on level RISE
10
5
3†
 
10
5
-4814
-4814
-14
UL
DP-DT two SP-DT switches
4
2
1†
 
4
2
-4806
-4806
-06
UL
CHART B
snap action contacts
SP-DT one switch
12
5
3†
 
0.5**
0.25**
-7810
-7810
-10
UL
DP-DT Two SP-DT switches
12
5
3†
 
0.5**
0.25**
-7806
-7806
-06
UL
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.

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