Schmersal magnetic non-contact safety sensors — dominated by the BNS series — provide wear-free, reliable guard position monitoring for industrial machines. Unlike traditional mechanical safety switches that rely on physical contact, these sensors detect the guard position through magnetic induction, making them the preferred choice for applications with frequent opening, door misalignment, or heavy dust and oil contamination.
How Magnetic Non-Contact Safety Sensors Work
Traditional mechanical safety switches rely on physical contact for signal triggering, which often leads to contact wear and jamming failures after frequent opening and closing. Schmersal BNS series sensors from Germany solve this with a fundamentally different principle: the sensor body and the magnetic actuator communicate through magnetic induction with no mechanical contact.
Classified as coded non-contact interlocking devices per EN ISO 14119, these sensors cut the safety circuit and stop hazardous machine movements the moment the guard door opens and the magnetic field moves away from the sensor. With no moving parts in the sensing zone, there is nothing to wear out — which is why BNS sensors deliver decades of reliable service in demanding environments.
The BNS Series from Schmersal
Schmersal's magnetic non-contact safety sensors are dominated by the BNS series, matched with supporting BPS magnetic actuators. The family is available in three form factors to suit different machine designs:
- Compact square housings — the standard choice for most machine guards, e.g. BNS 36-02/10Z-R
- Cylindrical versions — for recessed or tight installation spaces
- Stainless steel hygienic types — for food and pharmaceutical environments requiring washdown resistance
Popular BNS Models
The following 20 models are among the most widely requested BNS variants:
- BNS260-02Z-ST-L
- BNS260-02/01ZG-ST-R
- BNS260-11Z-L
- BNS303-02ZG-ST-2211
- BNS303-12Z-ST
- BNS300-01ZG
- BNS333-01Y-SK
- BNS36-11Z-ST-L
- BNS36-12Z-R
- BNS16-11Z-ST
- BNS250-11Z
- BNS250-12Z-2187
- BNS40S-12Z-C
- BNS33S-12Z
- BNS180-11Z
- BNS120-12Z-2187
- BNS30-11Z
- BNS260-11ZG-ST-R
- BNS303-11Z-ST-2211
- BNS16-12Z-AS
Representative stock models in our catalogue include the BNS 36-02/10Z-R 5,0M, BNS 180-12Z-2187-2, BNS 40S-12ZG-C 3,0M and BNS 303-02Z-2211 2,5M. Browse the complete magnetic contactless sensors category for the full range.
Typical Applications
BNS magnetic safety sensors are widely used across automated industries, especially where frequent switching, misalignment or contamination rules out mechanical switches:
- Food and beverage processing equipment
- Pharmaceutical clean production lines
- Lithium battery production equipment
- Robot safety fences and enclosures
- CNC machine tools
- Rubber and plastics injection machinery
- Packaging automation lines
- Textile and printing machinery
- Logistics sorting and conveying systems
- Escalator inspection cover monitoring
- Woodworking and construction machinery
- Rail transit detection devices
Buying Guide for Glorient Customers
Glorient supplies genuine Schmersal BNS magnetic safety sensors and BPS actuators with competitive pricing and worldwide delivery. To order the correct part:
- Identify the model on your existing sensor or its nameplate (e.g. BNS 303-02Z-2211).
- Confirm whether you also need the matching BPS magnetic actuator.
- Send the details via the quote request form — we will confirm availability and price within 24 hours.
For the logic side of your safety circuit, see our guide on safety relay selection — the BNS sensor and the safety relay work together to achieve the required performance level. If you are unsure which BNS variant fits your guard, send us a photo of the nameplate and our engineers will match it.
Related Magnetic Contactless Sensors
Browse the complete Schmersal Magnetic Contactless Sensors range. Representative models available through Glorient:
As coded non-contact interlocking devices per EN ISO 14119, BNS sensors support PL e circuits. Read SIL vs PL Explained: Performance Levels, Safety Categories and Component Selection for the levels behind these ratings.
Frequently Asked Questions
How do magnetic safety sensors differ from mechanical door switches?
Schmersal BNS series magnetic sensors use coded magnetic actuation with no mechanical contact, so they are wear-free, tolerant to door misalignment and immune to dust and oil. They are the preferred choice for guards that open and close frequently.
What does "coded" actuation mean and why does it matter?
Coded actuators prevent tampering and defeat using simple magnets. Per EN ISO 14119, coded non-contact interlocking devices provide a higher level of protection against bypassing the safety function.
Can BNS sensors be used in washdown environments?
Many BNS variants are sealed to IP67 or IP69K and are suitable for food, beverage and pharmaceutical washdown environments where equipment is regularly cleaned with high-pressure water.