In the world of process automation, “Universal Compatibility” is the holy grail. Imagine a facility with five different brands of rotary actuators and ten different brands of limit switch boxes. Without a common language, the engineering team would be forced to design and machine custom brackets for every single valve—a nightmare of cost and complexity.
This is where the NAMUR Standard, formally known as VDI/VDE 3845, comes into play. It is the international “handshake” between an actuator and its accessories.
At Zhejiang KGSY Intelligent Technology Co., Ltd., every limit switch box we manufacture—from the compact APL-210N to the heavy-duty KG800-Ex—is designed to be 100% NAMUR compliant. This guide explains why this standard is the backbone of valve automation and how it ensures a seamless fit for your KGSY equipment.
1. What is NAMUR (VDI/VDE 3845)?
NAMUR is an acronym for the “User Association of Automation Technology in Process Industries” (an influential German group). The VDI/VDE 3845 standard specifically defines the mounting patterns for automated valves.
The Two Interfaces
The standard defines two critical areas of connection:
- The Shaft (Output): The top of the actuator shaft must have a specific “slot” or “tongue” geometry to drive the accessory.
- The Mounting Holes (Enclosure): The spacing of the threaded holes on the top of the actuator where the accessory bracket will be bolted.
2. The NAMUR Shaft: The “Drive” Connection
Every KGSY limit switch box features a standardized shaft that mirrors the NAMUR requirement.
The Standard Dimensions
The most common NAMUR shaft dimensions used in the industry, and supported by KGSY, are:
- Height: 20mm or 30mm (Distance from the top of the actuator to the top of the shaft).
- Slot Width: 4mm.
- Shaft Diameter: Typically 16mm or 20mm with a flat “milled” top.
Why it Matters
Because KGSY shafts follow this standard, our internal cams (which trigger the SPDT or DPDT switches) are perfectly aligned with the valve’s movement. There is no “slop” or mechanical play in the connection. When the valve moves 90 degrees, the KGSY indicator moves exactly 90 degrees, ensuring the control room receives 100% accurate feedback.
3. The Mounting Hole Pattern: The “Support” Connection
The VDI/VDE 3845 standard specifies the distance between the four mounting holes on the top of the actuator.
Standard Sizes (A x B)
The NAMUR standard categorizes these into sizes based on the actuator’s footprint:
- 30 x 80 mm: The most common standard for small to medium actuators.
- 30 x 130 mm: Used for larger actuators.
The KGSY Modular Bracket
At KGSY, we provide a Stainless Steel Multi-Bracket as a standard accessory. Our brackets are engineered with slotted holes that cover both the 80mm and 130mm spacings. This means one KGSY kit can be mounted on almost any actuator in your plant, reducing your inventory requirements.
4. The Benefits of NAMUR Compliance for Engineers
Choosing a NAMUR-compliant device like the KGSY DSK series provides three primary technical advantages:
1. Zero Custom Machining
In the past, mounting a switch box required a machine shop to drill and tap custom plates. With the NAMUR standard, it is a “bolt-on” procedure. A technician only needs an Allen key and five minutes to install a KGSY box.
2. Interchangeability
If a facility currently uses a competitor’s limit switch box and it fails, a KGSY ALS-400 can be swapped in immediately. Because the mounting footprint and shaft drive are identical, the downtime is minimized to minutes rather than hours.
3. Precise Visual Indication
The NAMUR shaft ensures that the 3D Dome Indicator is centered. If the shaft were off-center, the visual beacon would wobble or sit crookedly, making it difficult for operators to read the valve status correctly.
5. KGSY and the NAMUR “Full Loop”
KGSY doesn’t just stop at the limit switch box. The NAMUR standard also applies to the Solenoid Valve interface on the side of the actuator.
Our switch boxes are designed to facilitate this “Full Loop”:
- The cable entries (NPT or M20) allow wiring for both the switches and the solenoid to enter the same box.
- The terminal strip inside the KGSY box acts as a junction point for the solenoid, which is typically mounted to the NAMUR interface on the actuator body.
This creates a clean, organized, and standardized “Automation Stack” where every component speaks the same mechanical language.
6. How to Verify NAMUR Compatibility
When ordering from KGSY, you can be confident in our compliance. However, here is how to verify your actuator is ready:
- Check the top of your actuator: Do you see four threaded holes in a rectangle? Measure the distance between them. If it is 80mm or 130mm wide, it is NAMUR.
- Look at the shaft: Is there a slot (usually 4mm wide)? If so, the KGSY shaft will drop right in.
- Shaft Height: Measure if your actuator shaft is 20mm or 30mm above the housing. KGSY brackets are adjustable or come in specific heights to accommodate both.
7. Conclusion: Quality is Standardized
At Zhejiang KGSY Intelligent Technology Co., Ltd., our commitment to “Quality is Credibility” extends to our adherence to international standards. By following the NAMUR VDI/VDE 3845 standard, we ensure that our products are a “Global Fit.”
Whether you are an OEM actuator manufacturer or an end-user in a refinery, KGSY’s NAMUR-compliant designs eliminate the guesswork. You get a robust, reliable, and perfectly aligned valve monitoring system every time.
Ready to standardize your valve automation?
Download our mounting dimension sheets or contact our technical support team for the specific CAD drawings of our NAMUR brackets.
- Website: www.chinakgsy.com
- Email: manager@zjkgsy.com
- Phone/WeChat: 086-13587661980
- Address: Building 8, No. 377 Branch Road of Binhai 12 Road, Wenzhou Economic Development Zone, Zhejiang, China.
Post time: Mar-04-2026
