Description
Core Product Summary
The TopWorx DXP-L21ZNEB is a DXP-series discrete valve controller and switchbox from Emerson TopWorx. It provides open and closed valve-position indication for automated linear or rotary valve actuators.
This configuration uses two hermetically sealed SPDT GO Switches in a tropicalized aluminum enclosure. It is described as explosionproof/flameproof, includes a NAMUR-style position indicator with a yellow open and black closed display, and provides two 3/4 in NPT conduit entries.
Key Technical Specifications
| Parameter | Specification |
|---|---|
| Manufacturer | Emerson / TopWorx |
| Model | DXP-L21ZNEB |
| Product type | Discrete valve controller / switchbox |
| Series | TopWorx DXP |
| Switch configuration | 2 × SPDT GO Switches |
| Switch construction | Hermetically sealed |
| Housing material | Tropicalized aluminum |
| Enclosure protection | Explosionproof / flameproof |
| Position indicator | NAMUR-style, yellow open / black closed |
| Conduit entries | 2 × 3/4 in NPT |
| Valve automation compatibility | Linear and rotary valve actuators |
| Switch option code | L |
| L-option contact form | SPDT dry contact |
| L-option electrical rating | 4 A at 120 V AC; 3 A at 24 V DC |
The L switch option is documented in the TopWorx D-Series configuration information as a gold-flashed, dry-contact SPDT GO Switch rated 4 A at 120 V AC and 3 A at 24 V DC.
Engineering Selection Highlights
- Two SPDT GO Switches → provide separate open and closed position feedback contacts for a control system.
- L-option dry-contact SPDT switches → the connected PLC, DCS, or interlock input must be compatible with a dry contact and the documented 4 A / 120 V AC or 3 A / 24 V DC rating.
- Tropicalized aluminum enclosure → supports use in corrosive or humid industrial environments where a coated aluminum switchbox is required.
- Explosionproof / flameproof construction → hazardous-area installation must follow the applicable certification, grounding, and wiring requirements.
- NAMUR-style indicator with yellow open and black closed display → provides local visual confirmation of valve position.
- Two 3/4 in NPT conduit entries → field wiring and conduit hardware must match the NPT entry size and maintain the enclosure rating.
- Factory setting is 90° rotation, clockwise-to-close → nonstandard valve rotation or travel requires target and indicator reconfiguration.
DXP-L21ZNEB
DXP-L21ZNEB
System Compatibility & Integration Requirements
| Item / Dependency | Verified Compatibility or Requirement | Practical Note |
|---|---|---|
| Valve actuator | Linear or rotary valve automation | The switchbox mounts to the actuator bracket and monitors valve position. |
| Switch outputs | 2 × SPDT dry-contact GO Switches | Use the COM and NO/NC contacts according to the required open and closed indication logic. |
| Switch electrical rating | 4 A at 120 V AC; 3 A at 24 V DC for the L option | Do not exceed the contact rating; use appropriate protection and load sizing. |
| Conduit connection | 2 × 3/4 in NPT | Install approved conduit, plugs, and sealing fittings to preserve the enclosure protection. |
| Factory motion setting | 90° rotation, normal acting, clockwise to close | Reverse-acting or nonstandard rotation requires target relocation and indicator adjustment. |
| Mounting fasteners | 8 ft·lb / 10.8 N·m torque after valve cycling | Cycle the valve before final tightening so the shaft can self-center. |
| Calibration | Switch calibration must not be performed in a hazardous area | For the L option, calibration can be checked with an ohmmeter across COM and NO. |
The D-Series quick-start guide documents these installation, calibration, and wiring-related requirements for TopWorx D-Series products, including the L sensor option used by the DXP-L21ZNEB.
Dimensions, Mounting & Connection Notes
| Item | Installation Data |
|---|---|
| Mounting method | Switchbox mounted to the valve-actuator bracket |
| Mounting fastener torque | 8 ft·lb / 10.8 N·m |
| Shaft loading | Avoid undue axial thrust load on the shaft |
| Conduit entries | 2 × 3/4 in NPT |
| Factory rotation setting | 90°, normal acting, clockwise to close |
| Target adjustment torque | 20 in·oz for U-Set target locking |
| Shipping protection | Temporary vinyl covers; permanent sealing devices required for installation or outdoor storage |
The switchbox must be mounted with sound mechanical practice, and final fastener tightening should occur after cycling the valve so the actuator shaft self-centers. Temporary shipping covers do not preserve the IP/NEMA rating; permanent conduit, plugs, and sealing devices are required for installed service.
Detailed Product Overview
The TopWorx DXP-L21ZNEB is a discrete valve controller configured with two hermetically sealed SPDT GO Switches. Its role is to provide electrical confirmation of valve position: one switch can indicate the closed position and the other the open position, depending on the configured control logic. The switchbox is part of Emerson’s TopWorx DXP discrete valve controller range.
The L sensor option defines the contact type and electrical boundary. It is a gold-flashed, dry-contact SPDT GO Switch rated for 4 A at 120 V AC or 3 A at 24 V DC. Because these are dry contacts, the associated control circuit must provide the sensing voltage and appropriate current limiting or protection. The D-Series guidance specifically warns that a direct power source used during calibration requires an appropriately sized series resistor to avoid permanent contact damage.
The enclosure is tropicalized aluminum and is described as explosionproof/flameproof. The NAMUR-style indicator provides local position indication, with yellow representing open and black representing closed. Two 3/4 in NPT conduit entries provide the field-wiring interface; maintaining the enclosure rating depends on correctly installed conduit, plugs, and any required sealing fittings.
Mechanically, the unit is intended for both linear and rotary valve automation. Emerson documents a factory preset of 90° rotation with normal clockwise-to-close action. The U-Set target disk provides four target slots at 90° increments, allowing the switchbox to be rotated 90°, 180°, or 270° from the standard orientation when the application requires it. Reverse-acting units transpose the switch function, and the indicator dome mask must be repositioned accordingly.
Calibration is a required commissioning step. For the L-option configuration, the D-Series guide permits verification using an ohmmeter across COM and NO; an active switch reads below 0.5 ohms. Calibration must not be performed in an area that could be hazardous, and intrinsically safe installations must follow the control drawing supplied with the product.
Applications & System Role
The DXP-L21ZNEB sits in the valve-position-feedback layer of an automated valve assembly. It is mounted on the valve actuator and converts mechanical valve travel into discrete open and closed switch signals for a PLC, DCS, interlock, or monitoring system.
TopWorx D-Series products are used on both linear and rotary valve automation applications. The two-switch configuration makes this model suitable for applications requiring independent open and closed status confirmation from a single valve actuator.
FAQ
What is the TopWorx DXP-L21ZNEB?
The TopWorx DXP-L21ZNEB is a DXP-series discrete valve controller and switchbox that provides open and closed valve-position feedback for automated valves.
How many switches does it include?
It includes two hermetically sealed SPDT GO Switches.
What type of switch contacts does the L option provide?
The L option provides gold-flashed, dry-contact SPDT GO Switches rated 4 A at 120 V AC and 3 A at 24 V DC.
What enclosure material is used?
The DXP-L21ZNEB uses a tropicalized aluminum enclosure with explosionproof/flameproof construction.
What conduit entries does it have?
It has two 3/4 in NPT conduit entries.
Can it be used on both linear and rotary valves?
Yes. TopWorx D-Series products are documented for use on both linear and rotary valve automation applications.
What is the factory valve-rotation setting?
The factory preset is 90° rotation, normal acting, with clockwise rotation closing the valve.
What torque is used to mount the switchbox?
Fasten the switchbox to the actuator bracket at 8 ft·lb / 10.8 N·m after cycling the valve.
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