Mobrey MVLSF Magnetic Vertical Float Level Switch

Vertical magnetic float level switch for direct top mounting

The Mobrey MVLSF is a vertical, float actuated magnetic level switch for direct mounting on top of a vessel. A float sized for the liquid is joined to a rod carrying a magnet. As the float rises with the liquid, the magnet actuates one or more switching units through a three-magnet, snap action, latching mechanism with no springs in the switch. A hermetically sealed switch option is available, and the rod length is adjustable within the limits of each float type.

Because the rod length is limited, the datasheet positions these switches for high or low level alarm duty. For tall vessels or on/off pump control it points to the displacer-type range instead. The same switches can be supplied mounted vertically in chambers, sealed or removable, with carbon steel or stainless steel chambers.

Technical specifications

Float types and pressure rating

Ordering code

The model code is built from twelve tables: base model D, flange material (C carbon steel, S 316L stainless steel), float function (11F to 17D), enclosure type, certification, enclosure material, cable entry, number of switches (one to six), switch type, connection size and type, and connection finishing. Enclosure R is 150 mm high for up to four switch mechanisms, S is 250 mm for up to six, and L is 375 mm. Contact options are D4 or D8 general purpose (2 kVA 440 Vac, 5 A), P4 or P8 gold alloy for low power and intrinsically safe circuits (0.25 A), X4 or X8 high current (10 A) and H4 or H8 hermetically sealed in inert gas with gold plated contacts (10 A). Certification codes include KN ATEX and IECEx flameproof, E5 FM, E6 CSA and NA for non-hazardous locations. Enclosure materials are aluminium alloy (A), cast iron (I) and aluminium alloy base with drawn steel cover (N).

How the Mobrey MVLSF works

A float rides on the liquid surface and moves a rod with a magnet on it. As the magnet passes the switching unit, its field flips a snap-action latching mechanism. The contacts change state at once and stay there until the float moves back. The switch has no springs, and the process liquid never reaches the contacts.

Where the MVLSF is used

• High level alarms
• Low level alarms
• Process vessels
• Storage tanks
• Sumps and receivers

Selection checklist for the MVLSF

• Liquid density, or specific gravity
• Float type
• Process temperature
• Process pressure
• Rod length
• Number of switching units
• Flange or NPT connection
• Direct or chamber mounting

Installation, commissioning and maintenance notes for the MVLSF

Mount the switch on top of the vessel with the float hanging vertically. Set the rod length so the float reaches the alarm level. Wire the terminals and close the housing. Test the switching by moving the liquid level or the float. Inspect the float for coating at regular intervals.

Requesting a quotation for the Mobrey MVLSF

Please send the liquid, the temperature, the pressure and the connection type. Seven Star LLC serves industrial customers in Oman and the GCC and replies with a quotation based on the information provided.

MVLSF mounting

The MVLSF mounts directly on top of a vessel.

MVLSF switching mechanism

It uses a three-magnet, snap action, latching mechanism.

MVLSF sealed option

A hermetically sealed switch option is available.

MVLSF rod length

The rod length is adjustable within the limits of each float type.

MVLSF process temperature

The process temperature runs from minus 10 to plus 400 degrees C on some types.

MVLSF ambient temperature

The ambient range is minus 50 to plus 60 degrees C.

MVLSF ingress protection

The rating is IP66.

MVLSF switch output

It offers up to six 2xSPST units or 4xSPST units.

MVLSF process connection

It has a 3 or 4 inch flange or a 1 inch NPT thread.

MVLSF rod and float material

The rod and float are 316 stainless steel as standard.

MVLSF float types

Floats include 11F, 12F, 13F, 14F and 17D, with minimum S.G. from 0.80 down to 0.40.

Level switch records for the MVLSF

Record the float type, the set level and the date of each function test.

Choosing the right MVLSF float

Choose the float from the lowest liquid density and the highest pressure at the site.

Documents and quotation

Confirm the specific gravity of the liquid, process temperature and pressure, number and function of switch points, flange or NPT connection, enclosure material and the hazardous-area certificate needed. The certification code must match the enclosure material, because some codes apply only to aluminium or cast iron housings.

The manufacturer document is attached to this page and listed below. Seven Star LLC is an independent supplier in Muscat and can quote against the model code, quantity and delivery location. Browse more instruments in Level Instrumentation, or see the Mobrey brand page.