Industriearmaturen Limit Switch Boxes

Limit Switch Boxes – Switchmaster and EB300 Series

Limit switch boxes report the open and closed position of a quarter-turn actuator back to the control system. Fergo supplies two product lines – Switchmaster (M2, D2, N2) and EB300 (PP, PE, VP, AP, VE, AE, VE-DB, AE-DB) – with mechanical, inductive or pneumatic signalling for industrial valve automation.

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Switchmaster Limit Switch Box

Variants: M2 (mechanical), D2 (inductive), N2 (Namur ATEX)

Protection:: IP67

Swing angle: 0–90°

Temperature range: –20 °C to +70 °C
Limit Switch Box EB300

Type: Limit switch box

Body: Polyamide, Aluminium, Vestamid

Switch Type: Mechanical, Inductive, Slot, Double Sensor, Potentiometer, Pneumatic, Reed Sensor

Product Overview

Limit Switch Box for Pneumatic Quarter-Turn Actuators – Position Feedback with Switchmaster and EB300

Limit switch boxes detect the end position of a pneumatic quarter-turn actuator and convert the mechanical rotation into an electrical, inductive or pneumatic signal. This signal communicates the current valve status – open or closed – to the distributed control system (DCS) or programmable logic controller (PLC). As a result, the limit switch box forms an essential component in every automated valve assembly.

Reliable position feedback increases plant safety and supports predictive maintenance planning. Without clear position confirmation, the control room cannot verify the actual valve state – an unacceptable condition in safety-critical applications. Additionally, operations staff can detect whether an actuator has reached its target position or whether a malfunction has occurred.

Fergo carries two proven product lines: the Switchmaster series (M2, D2, N2) with Lexan housing for premium requirements and the EB300 series with housings in polypropylene, conductive Vestamid or aluminium for standard and ATEX applications. Fergo mounts all models to the NAMUR standard VDI/VDE 3845 directly on pneumatic quarter-turn actuators.

Model Overview Table

01 Limit Switch Box Models at a Glance

Fergo offers ten limit switch box models across two series. The following table shows signal type, housing material, ATEX suitability and temperature range at a glance – helping engineers and maintenance teams identify the right model quickly and reliably.

Model	Series	Signal Type	Housing	ATEX	Temperature
M2	Switchmaster	Mechanical	Lexan 143	optional	–20 °C to +70 °C
D2	Switchmaster	Inductive	Lexan 143	optional	–20 °C to +70 °C
N2	Switchmaster	Pneumatic	Lexan 143	NAMUR ATEX	–20 °C to +70 °C
EB300-PP	EB300	Mechanical	Polypropylene	—	–20 °C to +60 °C
EB300-PE	EB300	Mechanical	PP + stainless steel bridge	—	–20 °C to +60 °C
EB300-VP	EB300	Mechanical / Inductive	Vestamid (conductive)	Zone 1/2, 21/22	–20 °C to +60 °C
EB300-AP	EB300	Mechanical / Inductive	Aluminium	Zone 1/2, 21/22	–20 °C to +70 °C
EB300-VE	EB300	Mechanical / Inductive	Vestamid + stainless steel bridge	Zone 1/2, 21/22	–20 °C to +60 °C
EB300-AE	EB300	Mechanical / Inductive	Aluminium + stainless steel bridge	Zone 1/2, 21/22	–20 °C to +70 °C
EB300-VE-DB / AE-DB	EB300	Dual chamber	Vestamid / Aluminium	Zone 1/2, 21/22	–20 °C to +60/+70 °C

02 Switchmaster and EB300 – Series in Detail

Switchmaster M2 – Mechanical Limit Switch Box

The Switchmaster M2 operates with mechanical microswitches and gold-plated contacts for a voltage range of 4 V DC to 250 V AC. The transparent Lexan 143 housing allows visual inspection of the cam position without opening the cover. Fergo supplies the M2 with IP67 protection, a 0–90° swing angle and tool-free cam adjustment for rapid commissioning.

Switchmaster D2 – Inductive Limit Switch Box

The Switchmaster D2 detects the valve position through inductive proximity sensors. Since no mechanical contact occurs, the D2 operates wear-free and achieves a significantly higher switching cycle count than mechanical variants. Fergo recommends the D2 particularly for applications with high switching frequency or difficult maintenance access.

Switchmaster N2 – Pneumatic Feedback (NAMUR ATEX)

The Switchmaster N2 provides purely pneumatic position feedback without electrical wiring. This makes the N2 particularly suitable for hazardous areas where electrical cables present an additional ignition risk. Fergo deploys the N2 in combination with NAMUR solenoid valves to create a fully pneumatic automation chain.

EB300-PP / EB300-PE – Standard Limit Switch Boxes

The EB300-PP uses a polypropylene housing and covers standard applications in non-hazardous areas. Fergo also offers the EB300-PE with a stainless steel bridge that provides more stable mounting on larger quarter-turn actuators. Both models operate from –20 °C to +60 °C and meet IP67 protection.

EB300-VP / EB300-AP – ATEX Limit Switch Boxes

For hazardous areas, Fergo supplies the EB300-VP with a conductive Vestamid housing and the EB300-AP with an aluminium housing. Both variants carry ATEX certification for Zone 1/2 (gas) and Zone 21/22 (dust). The Vestamid housing safely dissipates electrostatic charges, while the aluminium housing delivers maximum mechanical durability.

EB300-VE / EB300-AE – ATEX with Stainless Steel Bridge

Fergo supplements the ATEX range with the EB300-VE (Vestamid) and EB300-AE (aluminium), each with an integrated stainless steel bridge. The stainless steel bridge enables precise mounting on actuators with extended bolt patterns. Additionally, Fergo offers custom drilling patterns for the EB300-AE on request.

EB300-VE-DB / EB300-AE-DB – ATEX Dual Chamber Boxes

Dual chamber boxes separate two independent switching elements in individual housing compartments. Fergo delivers the EB300-VE-DB in conductive Vestamid and the EB300-AE-DB in aluminium. Both models suit safety-critical applications requiring two redundant position signals – for example in SIL loops or where separate open/closed evaluation by different control systems is required.

Housing Materials

Limit Switch Box Housing Materials

01 – Lexan 143 (Polycarbonate)

The Switchmaster housing consists of Lexan 143 – an impact-resistant polycarbonate with antistatic coating. The transparent material allows visual inspection of the cam position from outside. Fergo recommends Lexan for applications up to +70 °C in non-aggressive environments. Limitation: Lexan does not tolerate aromatic solvents or strong alkalis.

02 – Polypropylene

The EB300-PP and EB300-PE use polypropylene as housing material. Polypropylene provides good chemical resistance at low weight and cost. Fergo deploys polypropylene housings in standard plants that do not require ATEX certification. The operating range spans –20 °C to +60 °C.

03 – Conductive Vestamid (PA12)

Vestamid is a conductive polyamide that safely dissipates electrostatic charges. Fergo uses Vestamid in the ATEX-certified models EB300-VP, EB300-VE and EB300-VE-DB. The material meets the requirements of ATEX Directive 2014/34/EU for Zone 1/2 (gas) and Zone 21/22 (dust) within a temperature range of –20 °C to +60 °C. Compared to aluminium, Vestamid is lighter but offers lower mechanical robustness.

04 – Aluminium

Aluminium housings deliver the highest mechanical robustness in the range. Fergo supplies the EB300-AP, EB300-AE and EB300-AE-DB with aluminium housing for ATEX Zone 1/2 and 21/22. The operating range extends from –20 °C to +70 °C. Aluminium is particularly suitable for outdoor installations, aggressive industrial environments and applications with high mechanical stress.

Material	Temperature	ATEX	Weight	Chemical Resistance
Lexan 143	–20 to +70 °C	optional	Light	Good (not against aromatics/alkalis)
Polypropylene	–20 to +60 °C	—	Very light	Very good
Vestamid PA12	–20 to +60 °C	Zone 1/2, 21/22	Light	Good
Aluminium	–20 to +70 °C	Zone 1/2, 21/22	Heavy	Moderate (corrosion-prone without coating)

Signal Type Selection Guide

Choosing the Signal Type – Mechanical, Inductive or Pneumatic

The signal type determines reliability, maintenance effort and deployment options of the limit switch box. Fergo supplies mechanical, inductive and pneumatic variants – depending on switching frequency, environmental conditions and control architecture, engineers select the optimal solution.

Criterion	Mechanical (M2, EB300)	Inductive (D2, EB300)	Pneumatic (N2)
Signal principle	Cam actuates microswitch	Cam detected without contact	Compressed air signal via cam control
Voltage	4 V DC – 250 V AC	10–30 V DC (typical)	None (purely pneumatic)
Wear	Contact wear after high cycle count	Wear-free	Wear-free
ATEX suitability	With ATEX housing (EB300-VP/AP)	With ATEX housing (EB300-VP/AP)	Inherently safe (no electrics)
Wiring	Electrical cable to DCS/PLC	Electrical cable to DCS/PLC	Pneumatic tubing
Typical application	Standard plants, water treatment, HVAC	High-frequency switching, hard-to-reach locations	Hazardous areas, chemical, petrochemical
Maintenance	Replace switch after wear	Virtually maintenance-free	Virtually maintenance-free

For standard plants with moderate switching frequency, engineers typically choose the cost-effective mechanical variant. Fergo recommends the inductive solution for high switching frequency or hard-to-reach mounting locations. In hazardous areas without electrical infrastructure, the pneumatic N2 offers the safest alternative. Additionally, Fergo integrates a SIPART PS2 positioner on request for continuous position feedback via 4–20 mA.

ATEX Limit Switch Boxes for Hazardous Areas

Limit switch boxes in hazardous areas must comply with ATEX Directive 2014/34/EU. Fergo supplies ATEX-certified models for gas zones (Zone 1 and 2) and dust zones (Zone 21 and 22). The following assignment shows which models suit which zone classification.

Zone 1/2 (gas) and Zone 21/22 (dust): EB300-VP, EB300-AP, EB300-VE, EB300-AE, EB300-VE-DB, EB300-AE-DB
Pneumatic ATEX solution: Switchmaster N2 – purely pneumatic, no electrical ignition source
Not ATEX-suitable: EB300-PP, EB300-PE (polypropylene, non-conductive)

During selection, Fergo considers the zone classification set by the plant operator. In Zone 1 (gas occasionally present) and Zone 21 (dust occasionally present), only models with conductive housing (Vestamid or aluminium) or the purely pneumatic N2 qualify. The same requirements apply to Zone 2 and Zone 22, as all ATEX models in the range carry Equipment Group II, Category 2 certification.Furthermore, Fergo combines ATEX limit switch boxes with explosion-protected NAMUR solenoid valves and pneumatic quarter-turn actuators into complete ATEX-compliant automation packages.

All limit switch boxes in the Fergo range comply with the relevant European standards for industrial valve automation:

VDI/VDE 3845 (NAMUR): Standardised mounting interface for position indicators and solenoid valves on pneumatic quarter-turn actuators. Fergo delivers all models with NAMUR-compatible mounting.
IP67 per EN 60529: Protection against temporary immersion and complete dust ingress. All Switchmaster and EB300 models achieve IP67.
ATEX 2014/34/EU: Certification for hazardous areas Zone 1/2 (gas) and Zone 21/22 (dust) – applies to Vestamid, aluminium models and the pneumatic N2.
CE marking: Conformity with the Low Voltage Directive 2014/35/EU and the EMC Directive 2014/30/EU.

Fergo ships all Switchmaster and EB300 limit switch boxes from stock in Neuss, Germany. Standard delivery takes 2–7 working days via DHL across the United Kingdom, Scandinavia and the rest of Europe. For project-specific requirements, customers contact the Fergo sales team.For custom specifications – such as special drilling patterns, pre-assembled cable lengths or complete packages with actuator, NAMUR valve and limit switch box – the Fergo custom solutions team is available.