Model 709

SKU: 709

Float Switch, Top Inserted, Single Point

The Delta Controls Model 709 Float Switch is a simple mechanical device which is highly reliable over long periods of time. An alarm switch-type action is provided as the liquid level surface passes through the elevation where the sensing float has been positioned. The sensing float is attached to a vertical shaft, which can move up and down. Lifting the float causes the output switch station to activate. The switch station is on the outside of a solid, non-magnetic pipe wall. This isolation eliminates the possibility of leaking seals and flex tube failures, which are problems in many other designs.

The 709 is commonly used for high level alarms and shutdown on tanks. An optional support bracket allows the 709 to also be used in sumps and pits. The float may be extended down into the tank as far as 12 feet (beyond 12 feet, the float can no longer lift the weight of the long and heavy float rod). This allows it to provide switch action as far as 12 feet down into the tank and allows the 709 to be used as a low-level alarm.

Unlike most competitive switches, the 709 float rod guide is always located just three inches above the float and thus avoids the need for any type of ‘stilling well.’ Moderate swirling or fluid motion will not damage the 709. A permanent magnet is attached to the actuating lever of the switch. As the liquid level rises, the float is carried upwards and the attractor is carried into the field of the magnet. The magnet is attracted and pulled against the wall of the sealing tube. This movement actuates the output switch. When the liquid level falls, the float drops, the attractor is pulled out of the field of the magnet and the output switch returns to its original position. The non-magnetic heavy-duty sealing tube provides a leakproof static barrier to the process fluid. The magnetic lines of force are the only coupling; failure prone couplings such as shafts with o-rings, diaphragms, bellows, etc have been eliminated to improve operation and reliability.


  • Simple mechanical device
  • High reliability
  • Sensing float
  • High level alarms
  • Float guide always located 3 inches above float
  • Non-magnetic, heavy-duty sealing tube


  • Available Wetted Materials: 316 Stainless Steel, carbon steel
  • Insertion (Below Process Connection): ≤ 10 ft (3 m)
  • Switch Action: Single point
  • Sensing Element: 316 Stainless Steel
  • Specific Gravity: 0.35 to 2.40
  • Temperature: From -150 °F to +750 °F (-101 °C to +399 °C)
  • Pressure: -15 psig to +1200 psig (-1 bar to +80 bar)
  • Process Connection:
  • Threaded: 1.0 in to 4.0 in MPT
  • Flanged: 2.0 in to 8.0 in
  • Rating: ≤ 300 lb ANSI flanges or Greloc® hub DIN or JIS equivalents

Certifications & Approvals

  • Third Party Listed by CSA NRTL/C (USA and Canada)
    Class I, Division 1, Groups B, C and D;
    Class II, Division 1, Groups E, F and G;
    Class III, Division 1
    Class I, Zone 1, Ex d IIB+H2
    Class I, Zone 1, AEx d IIB+H2

Required Ordering Information

  • Detailed model number
  • Tag or nameplate detail (if required)
  • Documentation/testing tiers (if required, refer to Additional Resources in the product catalog)
  • Process fluid or material name*
  • Process fluid or material specific gravity
  • Maximum process temperature
  • Maximum process pressure
  • Upper and lower materials required for interface service

Additional Information


Float Switch, Top Inserted, Single Point

Level Measurement


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