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Float Operated Liquid Level Switch


Mobrey M-Switch

Float Operated Liquid Level Switch

  • Reliably detects the liquid level to give a voltage free contact operation for alarm signalling or as a part of a pump control system
  • Small in-tank dimensions, suitable for use where space in a vessel is limited
  • Available for side mounting with either a flanged of 2-in. threaded connection
  • Tough industrial build quality with 316 Stainless steel construction throughout
  • European directive compliance
  • ATEX and IECEx flameproof models (Ex d)


MOB-SMA1 Diagram



Attribute Value
Device Type Level Alarm Switch
Mounting Type Side Mount
Switch Output SPDT
Body Material Stainless Steel
Minimum Operating Temperature 0°C
Maximum Operating Temperature +130°C
Maximum Current 15 A ac, 250 mA dc
Maximum Pressure 19bar
Gasket Material Non Asbestos Carbon Fibre

 M-Switch Specifications

Product M-Switch Float Operated Liquid Level Switch
Minimum liquid specific gravity 0.75
Differential 1 in. (25mm)
Length into tank 6 in. (153mm)
Float diameter Ø1.9 in. (Ø48 mm)
Maximum float swing 4.4 in. (112 mm)
Switching function (See Figure 1) SPCO (Single-Pole-Change-Over) relay
Construction materials
Wetside material 316 Stainless steel
Body material 316 Stainless steel
End cover material 316 Stainless steel
Gasket Non-asbestos for Mobrey 'A' flange
Ethylene propylene for Mobrey 'D' flange
Conduit entry M20 for flanged and BSPT threaded versions
  1/2-in. NPT for NPT threaded versions
Maximum voltage and current See Table 3 for the maximum voltage and current

The microswitch contacts are gold-plated and are suitable for use in low-power circuits.

Switching high-power circuits can permanently damage the gold-plating.

Not suitable for the direct starting of large motors.

Operating temperature 32 to 266°F (0 to 130°C)
Ambient temperature 32 to 140°F (0 to 60°C)
Operating pressure See Table 2 for the maximum pressure ratings
Enclosure ratings

Weatherproof M-Switch:

IP66/67 (NEMA 4)


Flameproof M-Switch:

ATEX: II 1/2G Ex d IIC T6 Ga/Gb

IECEx: Ex d IIC T6 Ga/Gb

IP66/IP67 (NEMA 4)

Marine Germanisher Lloyd

Table 2. Maximum pressure ratings

Maximum P @ Troom
Weatherproof Flameproof
Mobrey 'A' flange 275 psi 19 bar 362 psi 25 bar
Mobrey 'D' flange 43 psi 3 bar Not applicable
2-in. BSPT threaded 275 psi 19 bar 720 psi 49.6 bar
2-in. NPT threaded 275 psi 19 bar 720 psi 49.6 bar

Table 3. Maximum voltage and current

voltage and current


Max. voltage (V) 250 250 250
Max. current (A) 15 0.25 15

 Fig1 M-Switch

 Mobrey Dimensions

Table 4. Mobrey flange dimensions(1)

Mobrey Flange A B C D(2)
Mobrey 'A' Flange 3.6 (92) 0.55 (14) 3.6 (92) 2.6 (66)
Mobrey 'D' Flange 3.6 (92) 0.35 (9) 3.3 (83) 2.0 (50)

(1) Dimensions are in inches (mm)

(2) Mounting hole diameter D to be ±0.4 in. (1 mm).




1 Product

Mobrey Switch Mechanism To Suit SMA1/SMA2

Excl. VAT: £313.88

Incl. VAT: £376.66

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