Reliable level control is essential in machinery, hydraulic oil tanks, small storage tanks, bilge applications, and compact industrial systems. In these applications, the level switch must be durable, easy to install, economical, and resistant to different liquid conditions.
The ELM 51s Level Switch is designed as a practical solution for these requirements. As part of the ELM magnetic float level switch series, it provides dependable on/off level detection with stainless steel wetted parts, cable connection, and a protected body design suitable for demanding tank environments.
What Is ELM 51s?
ELM 51s is a vertical level switch used for tank level control. In the ELM product family, it is defined as a cabled and protected model, suitable for bilge applications.
Its compact structure makes it ideal for limited-space installations, while its stainless steel construction allows safe use with various liquids. The model is especially suitable for machine manufacturers, small tank systems, hydraulic reservoirs, and bilge level monitoring applications.
Operating Principle
The ELM series works with a magnetic float and reed sensor principle. Inside the float, there is a magnet that moves according to the liquid level. When the magnetic field of the float reaches the reed sensor inside the tube, the electrical circuit opens or closes.
When the float moves away from the switching point, the reed sensor returns to its original position. This simple and reliable switching principle enables the level information to be used in alarm, pump control, filling, emptying, or safety applications.
Vertical Mounting Structure
ELM 51s is designed for vertical mounting. This structure makes it suitable for applications where the liquid level must be monitored from the top or bottom of the tank, depending on the tank design and required switching point.
The vertical configuration provides practical installation in compact vessels and small reservoirs. It is particularly useful where side-mounted level switches are not suitable or where the installation area is limited.
Designed for Bilge and Protected Applications
One of the distinguishing points of ELM 51s is its protected and cabled design. The catalog identifies the 51s version as a cabled, protected model for bilge applications.
This makes ELM 51s suitable for applications where liquid level detection must remain reliable in compact and potentially harsh tank conditions. Its protected structure helps support stable operation where splashing, movement, or installation constraints may be present.
Technical Specifications
ELM 51s has a vertical mounting type. The float material, wetted parts, and tube material are 304 stainless steel as standard, with 316 stainless steel available as an option.
The float type is S40A, and the maximum operating temperature is 125 °C. The maximum pressure rating is 30 bar, and the minimum liquid density is 0.80 g/cm³.
The electrical connection is made by cable. The catalog shows the model with a 2-meter cable. ELM 51s has one standard float and one contact output. The contact structure is 1 x SPDT-NO/NC, with a contact current of 1.5 A, maximum contact power of 50 W / VA, and maximum supply voltage of 200 VDC / 250 VAC.
Electrical Output and Control Integration
ELM 51s provides a reed switch contact output that can be used directly or through a relay circuit. The output can be integrated into pump control systems, alarm panels, PLC inputs, or liquid level control circuits.
The model can also be used with the optional SK-P2 liquid level relay. This allows the level switch signal to be evaluated more easily in start-stop, alarm, filling, or emptying applications.
Application Areas
ELM 51s is suitable for machinery, hydraulic oil tanks, small tank applications, bilge systems, and similar liquid level control applications.
Its compact stainless steel construction makes it practical for OEM machine manufacturers and system integrators who need a simple, reliable, and economical level switch for limited-space installations.
Advantages of ELM 51s
The main advantages of ELM 51s are its economical design, compact dimensions, easy installation, stainless steel construction, and reliable reed switch operation.
Because it has a magnetic float-based structure, it provides dependable on/off level detection without requiring complex electronics at the measuring point. Its protected and cabled design makes it especially useful for bilge and small tank applications where practical installation is important.
Why Choose ELM 51s?
ELM 51s is a suitable choice when a compact vertical level switch is required for reliable tank or bilge level control. Its stainless steel wetted parts, 30 bar pressure rating, 125 °C temperature capability, and SPDT contact structure provide flexibility for different industrial control scenarios.
For machinery manufacturers and industrial users looking for a practical, durable, and easy-to-install level switch, ELM 51s offers a balanced solution between performance, simplicity, and cost efficiency.
Conclusion
The ELM 51s Level Switch is a compact and reliable solution for vertical liquid level control in bilge systems, machinery, hydraulic oil tanks, and small tank applications. With stainless steel construction, protected cabled design, magnetic float operation, and optional SK-P2 relay compatibility, it provides practical and dependable level detection for industrial use.
Its simple structure, easy integration, and robust technical specifications make ELM 51s an effective choice for applications requiring economical and reliable liquid level monitoring.