Description
The LS-21-100 Stainless Steel & Buna Single-Level Float Switch is a compact, high-performance level sensor designed for dependable operation in moderate-temperature and chemically exposed environments. With a durable 316 stainless steel stem and a buoyant Buna-N float, this unit offers the perfect balance of strength, chemical compatibility, and cost-efficiency for a wide range of liquid level control applications.
This float switch is particularly well-suited for use in industrial tanks, fluid reservoirs, and chemical processing systems where pressure resistance and reliability are essential. Rated for a maximum pressure of 150 PSI and an operating temperature range of -40°F to 180°F in water (up to 230°F in oil), it is capable of maintaining consistent performance in demanding process conditions. Its design allows it to function in applications involving water, oils, fuels, or mild chemicals without compromising its accuracy or longevity.
The float activates at a specific gravity of 0.50, making it suitable for many common industrial and commercial liquids. The SPDT reed switch offers a 3 VA rating, with support for up to 100 VAC/DC and a maximum switching current of 0.25A, providing precise control for signaling, monitoring, or automated liquid level responses.
Equipped with 24-inch long, 20 AWG lead wires protected by PVC insulation, the LS-21-100 ensures secure electrical connectivity and resistance to environmental exposure. The switch is vertically mounted via a 1/8″ NPT thread, allowing straightforward installation in compact or space-limited systems.
Like other models in this series, the float orientation can be easily inverted to select between Normally Open (N.O.) or Normally Closed (N.C.) operation, adding versatility and control flexibility based on system design or safety requirements.
The unique combination of stainless steel construction and Buna float provides excellent resistance to corrosion, moderate temperatures, and vibration, making this switch ideal for OEM systems, process control panels, and a variety of automation tasks. It is also UL Recognized (File# E177423), confirming compliance with industry safety and quality standards.
For operations that demand consistent level sensing, reliable switching, and material compatibility, the LS-21-100 offers a durable, efficient, and cost-effective solution.
| Part # | Reed Switch | Dry State | Price |
| LS-21-101/2 | 70 VA SPST | N.O.* | $44.90 |
| LS-21-103/4 | 100 VA SPST | N.O.* | $49.30 |
| LS-21-105 | 3 VA SPDT | N.O. / N.C. | $50.40 |
| LS-21-106 | 25 VA SPDT | N.O. / N.C. | $51.50 |
| LS-21-107 | 100 VA SPDT | N.O. / N.C. | $52.60 |
* The dry state can be changed from Normally Open to Normally Closed by inverting the float.
Dry State: The condition of the reed switch when the tank is dry.
N.O.: Normally Open
N.C.: Normally Closed
SPST: Single Pole Single Throw
SPDT: Single Pole Double Throw
| Operating Temp | Maximum Pressure | Float Spec. Gravity |
| 180°F (-40°F to 230°F oil) | 150 PSI | .50 |
| Thread | Float | Lead Wires |
| 1/8″ npt | 1.187″ diameter | 20 AWG PVC 24″ |
