Measurement and Control Equipment

Stainless Steel Vertical Level Switch: Compact Solution for Small Tanks

Learn how compact stainless steel float switches with reed contacts, mounted vertically from the top or bottom of a tank, work and what their key specifications are.

ORFA Technical TeamUpdated: Oct 30, 20263 min read

Stainless steel vertical float level switch with reed contact

Reliable liquid level control in tanks ensures that pumps, valves and alarms switch at the right moment. Small tanks and tight spaces in particular call for a compact solution. A stainless steel vertical level switch is a robust float switch with a reed contact, mounted vertically from the top or bottom of the tank.

What Is a Stainless Steel Vertical Level Switch?

The switch consists of a stainless steel stem and a float with a built-in magnet that moves freely along it. A reed switch, completely sealed from the process, sits inside the stem. The float follows the liquid level up and down the stem and actuates the reed switch at the set point.

Working Principle

Float movement: Buoyancy keeps the float on the liquid surface.
Magnetic actuation: When the magnet in the float reaches the reed switch inside the stem, it pulls the contacts.
Contact change: A normally open (NO) contact closes or a normally closed (NC) contact opens.
Control: The signal is used by a pump, solenoid valve, alarm or control panel.

Because there is no physical contact between the reed switch and the liquid, the contacts are not affected by the medium or moisture.

Tip: Reed contacts are low-power. Instead of switching inductive loads such as pumps or contactor coils directly, use an interposing relay to extend contact life.

Advantages

Compact design: Suitable for small tanks and limited installation space.
Durability: Corrosion-resistant stainless steel; AISI 316 or PTFE-coated versions for aggressive liquids.
Flexible contact choice: NO or NC; on some models the function can be reversed by turning the float over.
Easy installation: Threaded connection for mounting through the tank roof or bottom.

Applications

Shipbuilding; sewage and bilge tanks
Waste water and fresh water tanks
Food industry
Fuel tanks
Acid, chemical and petrochemical tanks (with suitable materials)

Technical Data

Feature	Value
Body and float	AISI 304 (optional AISI 316, PTFE-coated)
Operating temperature	-10 / +125 °C
Max. operating pressure	16 bar
Connection	BSP or NPT thread (min. 3/8″)
Min. liquid density	0.8 g/cm³
Contact type	NO / NC
Max. switching voltage	400 V AC/DC
Max. switching power / current	60 VA / 1 A
Protection class	IP68 (optional Ex-proof)

None of the voltage, current and power limits may be exceeded; for example, at 230 V AC the 60 VA limit allows about 0.26 A.

Frequently Asked Questions

What liquid density does a vertical level switch need?

With the standard float it works in liquids with a density of at least 0.8 g/cm³. Lighter liquids require a separate float selection.

What is the difference between vertical and horizontal level switches?

A vertical switch is mounted from the top or bottom of the tank and the float moves along the stem. A horizontal switch is mounted through the side wall and is chosen when the tank roof is not accessible.

Can a pump be connected directly to the reed contact?

Not recommended. Reed contacts are low-power (60 VA); pumps and contactors should be switched via an interposing relay.

Conclusion

Stainless steel vertical level switches provide compact, sealed and long-lasting level control in small and medium tanks. With the right material, contact type and load connection, they operate trouble-free for years. For other solutions, see our level control devices page.

Online Store