DX-EFS 61 Exproof Flow Switch: Reliable Flow Detection for Hazardous Industrial Areas

In industrial plants, reliable flow detection is essential for protecting pumps, pipelines, heat exchangers, process equipment and electrical systems. When the process involves hazardous areas, explosive atmospheres or demanding temperature conditions, the selected flow switch must provide not only accurate flow monitoring but also certified safety.

The DX-EFS 61 Exproof Flow Switch is designed for detecting flow in pipes and protecting electrical equipment when flow starts or stops. With its ATEX-certified exproof housing, stainless steel wetted parts, adjustable flow setting and high-temperature capability, DX-EFS 61 provides a robust solution for industrial flow monitoring in hazardous environments.

What Is DX-EFS 61?

DX-EFS 61 is an exproof mechanical flow switch used to detect the presence or absence of flow in pipelines. It can be used with liquid, air and gas applications and is suitable for non-corrosive liquid fluids.

When flow in the pipe starts or stops, the switch provides open or closed contact information. This contact signal can be used to protect electrical equipment, stop a pump, start an alarm, activate a control circuit or provide flow status information to an automation system.

DX-EFS 61 is part of the DX-EFS flow switch family, together with DX-EFS 41. The DX-EFS 61 model is the high-temperature type, offering a higher working temperature range than DX-EFS 41.

Operating Principle

DX-EFS 61 operates with a paddle mechanism placed in the flow path. When fluid moves through the pipe, it pushes the paddle. This mechanical movement is transferred through the internal mechanism to a microswitch.

When the flow reaches the adjusted set point, the contact changes state. When flow decreases below the return point, the switch returns to its previous state.

The internal structure includes a spring, microswitch, bellows, union connection and paddle. Different paddle lengths are used according to pipe size. This allows the device to be adapted for pipe sizes from 1" to 8".

Adjustable Flow Setting

The flow setting is made with a screw mechanism. The adjustment screw is factory set, but users can change it according to the application.

For higher flow setting, the adjustment screw is turned counterclockwise. For lower flow setting, the adjustment screw is turned clockwise. After adjustment, the cover must be closed correctly.

This adjustable structure allows DX-EFS 61 to be adapted to different pipe sizes, flow rates and process requirements.

ATEX and Exproof Certification

DX-EFS 61 is designed for hazardous area applications. The catalog lists certification for gas and dust atmospheres, including:

II 1/2G Ex db IIC TX Ga/Gb for gas
II 2D Ex tb IIIC TX Db for dust

The device is designed for ambient temperature conditions between -20 °C and +60 °C and has IP66 / IP68 protection up to 2 meters.

This makes DX-EFS 61 suitable for hazardous industrial areas where explosion protection and reliable flow monitoring are required.

Technical Specifications

DX-EFS 61 is suitable for liquid, air and gas applications. Its working temperature range is -40 °C to +175 °C, and maximum working pressure is 20 bar.

The paddle material is 304 stainless steel, with 316 stainless steel available as an option. The switch bracket is 304 stainless steel. The connection material and paddle rod are 304 stainless steel, with 316 stainless steel optional.

The enclosure material is aluminum, and the bellows material is 316 stainless steel. The process connection is 1" NPT male thread, and the electrical connection is M20 x 1.5 mm.

The contact rating is 15 A 250 VAC, with NO/NC output. The protection class is IP66 / IP68.

High-Temperature Flow Monitoring

The main difference of DX-EFS 61 is its high-temperature capability. While DX-EFS 41 is rated up to +145 °C, DX-EFS 61 is rated up to +175 °C.

This makes DX-EFS 61 suitable for applications where process temperatures are higher and standard flow switches may not be sufficient.

Applications may include hot liquid lines, thermal process systems, energy plants, chemical processes and industrial utility lines where flow status must be monitored under elevated temperature conditions.

Flow Range and Paddle Selection

The catalog provides paddle lengths and flow setting values according to pipe size. Paddle lengths include 35 mm, 60 mm, 90 mm and 150 mm depending on pipe diameter.

For 1" pipe, the paddle length is 35 mm, maximum flow is 3.6 m³/h, minimum setting switch action is 0.8 m³/h, and maximum setting switch action is 1.9 m³/h.

For 2" pipe, the paddle length is 60 mm, maximum flow is 15 m³/h, minimum setting switch action is 3.0 m³/h, and maximum setting switch action is 6.4 m³/h.

For 4" pipe, the paddle length is 90 mm, maximum flow is 60 m³/h, minimum setting switch action is 14.0 m³/h, and maximum setting switch action is 28 m³/h.

For 8" pipe, the paddle length is 150 mm, maximum flow is 240 m³/h, minimum setting switch action is 80 m³/h, and maximum setting switch action is 170 m³/h.

These values help users select and adjust the correct configuration according to pipe diameter and required switching point.

Installation Recommendations

Correct installation is important for reliable flow detection. The flow direction must follow the direction shown on the cover or product label.

The device should be installed on the return pipe. It must also be mounted at a suitable distance from turbulence sources such as corners, elbows and pumps.

This helps prevent false switching and supports stable paddle movement. In industrial flow systems, correct installation is as important as product selection for long-term measurement reliability.

Electrical Connection

DX-EFS 61 uses terminal electrical connection inside the exproof housing. The catalog shows terminal assignments for NO, COM, NC and empty terminal, together with grounding.

The device includes a set adjustment screw, terminal block, grounding point and thermal fuse. For hazardous area applications, the cover must not be opened while energized and must be kept closed during operation.

This is especially important for maintaining exproof safety integrity.

Housing and Protection

The DX-EFS 61 uses B21x aluminum housing with IP66 / IP68 protection. The housing dimensions are 132 x 104 mm.

The housing has an EU-type examination certificate number TSE 22ATEX 0175U. The housing marking is listed as II 2G Ex d IIC Gb and II 2D Ex tb IIIC.

The cover gasket is NBR nitrile rubber, suitable up to 120 °C, with FPM / Viton option up to 200 °C.

The product label and metal label include model, serial number, working conditions, ATEX classes, approved body mark, explosive atmosphere protection and manufacturer information. If the product label is damaged on ATEX-certified products, the serial number on the metal label can be used to contact the manufacturer.

Temperature Class Information

The catalog includes a temperature class table for DX-EFS 41 and DX-EFS 61 metal models.

For Group II gas applications, the maximum process temperature determines the temperature class. The table lists:

T6 for process temperature below 80 °C
T5 for process temperature below 95 °C
T4 for process temperature below 125 °C
T3 for process temperature below 145 °C
T2 for process temperature below 175 °C

For Group III dust applications, the table lists T60 °C for process temperature below 60 °C.

The catalog also notes a 20-minute waiting time before opening the cover and states that the thermal protection fuse is 105 °C.

Application Areas

DX-EFS 61 can be used in several industrial sectors where hazardous area safety and reliable flow detection are required.

Typical application areas include chemical and pharmaceutical industry, water and wastewater systems, oil and gas industry, power plants and marine applications.

In these environments, the flow switch can help protect equipment, verify flow presence, prevent pump damage, support process interlocks and provide alarm information.

Key Advantages

DX-EFS 61 provides several important advantages for industrial users. It can be used with hot and cold fluids, has a fully sealed design and offers economical flow monitoring.

Its ATEX-certified exproof construction provides high safety for hazardous areas. The adjustable flow setting allows users to adapt the device according to application requirements.

The stainless steel wetted parts, aluminum exproof housing, IP66 / IP68 protection and 15 A relay output make it suitable for demanding industrial installations.

Why Choose DX-EFS 61?

DX-EFS 61 is a strong choice when a process requires reliable mechanical flow detection in hazardous areas. It combines exproof safety, high-temperature capability, adjustable flow set point and robust stainless steel wetted parts.

For applications where flow status must be monitored to protect electrical equipment, pumps or process systems, DX-EFS 61 provides a simple and dependable switching solution.

Its ability to operate up to +175 °C makes it especially suitable for higher-temperature applications compared with standard models.

Conclusion

The DX-EFS 61 Exproof Flow Switch is a reliable ATEX-certified flow switch for detecting liquid, air and gas flow in industrial pipelines. With -40 °C to +175 °C working temperature, 20 bar pressure rating, IP66 / IP68 protection, 1" NPT male process connection, 15 A 250 VAC NO/NC contact output and stainless steel wetted parts, it provides a robust solution for hazardous area flow monitoring.

From chemical plants and wastewater systems to oil and gas facilities, power plants and marine applications, DX-EFS 61 helps protect equipment, improve process safety and ensure reliable flow detection in demanding industrial environments.