Danfoss RT 121 Pressure Switch for Industrial & Marine Systems

A. Product Overview

The Danfoss RT 121 is part of the RT series of mechanical pressure switches developed for general industrial and marine use. It features a pressure-controlled single-pole changeover (SPDT) contact system that enables reliable alarm and control functions at very low operating pressures.

RT pressure switches are known for their simple mechanical construction, high accuracy, and long operational life. The RT 121 is specifically selected for applications requiring sensitive and repeatable pressure switching close to atmospheric pressure, where inaccurate sensing can lead to process instability or safety risks.

B. Working Principle

The RT 121 operates using a mechanical bellows-based pressure sensing element optimized for low-pressure ranges. When pressure is applied at the connection port, it acts on the bellows, moving the internal spindle. This movement actuates a snap-action SPDT contact mechanism.

When the pressure reaches the set range value, the contacts change state. The switch resets when pressure crosses the set value minus or plus the mechanical differential, depending on configuration. This purely mechanical operating principle ensures stable and repeatable switching without reliance on electronics, even in industrial and marine environments.

C. Key Applications

• Low-pressure industrial air systems

• Ventilation and auxiliary pressure monitoring

• Compressor control and protection circuits

• Utility and service pressure systems

• Marine auxiliary and onboard systems

• General industrial alarm and monitoring panels

D. Why Industries Use This Product

Industries use the RT 121 where accurate low-pressure monitoring is essential for system reliability and safety. Inadequate pressure control at low ranges can lead to inefficient operation, false alarms, leakage detection failures, or damage to sensitive equipment.

The RT 121 helps mitigate these risks by providing dependable and repeatable pressure-based switching at very low pressures. Its proven RT-series design supports long service life, minimal maintenance, and standardized installation across multiple plants. Availability of marine approvals further supports its use in shipboard and offshore systems.

E. Suitable Buyers

• Industrial OEMs and panel builders

• Utility and ventilation system integrators

• Marine equipment installers and shipyards

• Maintenance and reliability engineers

• Procurement teams sourcing standardized low-pressure switches

The RT 121 is commonly used as a replacement pressure switch in existing RT series installations and is preferred in retrofit projects requiring precise low-pressure control.

Quick Answers

What is Danfoss RT 121?
Danfoss RT 121 is a mechanical pressure switch designed for monitoring and controlling very low-pressure industrial and marine systems.

Where is Danfoss RT 121 used?
It is used in low-pressure air systems, ventilation circuits, compressors, utilities, and marine auxiliary installations.

Why is Danfoss RT 121 required in industry?
It provides accurate low-pressure switching, helping prevent process instability, equipment damage, and false alarms.

Who typically uses Danfoss RT 121?
OEMs, system integrators, maintenance teams, marine engineers, and industrial procurement professionals.

FAQ Section

Is Danfoss RT 121 suitable for very low-pressure applications?
Yes. The RT 121 is specifically designed for very low-pressure ranges and provides accurate, repeatable switching in industrial and marine systems.

Can RT 121 be used for alarm and control functions?
The SPDT contact system allows RT 121 to be used for both alarm signaling and direct control of auxiliary equipment.

Is RT 121 suitable for continuous-duty operation?
RT pressure switches are designed for long operational life and stable performance, making RT 121 suitable for continuous industrial operation.

Can RT 121 replace other RT series pressure switches?
Yes. RT 121 is commonly used as a replacement in existing RT installations where low-pressure operation is required.

Does RT 121 support standardized and marine-approved installations?
RT series pressure switches support standardized designs and are available with marine approvals suitable for shipboard and offshore installations.