Security Parts carries parts for the LCN Sentronic fire and life safety closer series (3130SE, 4040SE, 4040SEH, 2310ME, 4310ME, 4410ME, 4310HSA, 4410HSA), the SEM 7800 Series magnetic holders, the 4210/4510 Smoothee high-security surface closers, and the Auto Equalizer pneumatic (2610, 4810, 4820, 4840) and electric (4630, 4640) operators. All Sentronic closers require voltage specification at ordering time (24V or 120V). The solenoid is not separately replaceable: it must be ordered as part of the track or cylinder subassembly. The SEH holder requires an opposite-side closer. SEH installation without a confirmed opposite-side closer is a life safety code violation on fire doors.

The LCN specialty product lines serve applications that standard surface closers cannot address: fire and smoke barrier doors that must hold open during normal hours and self-close on fire alarm, high-security environments where closer hardware must resist tampering, and multi-door corridors where a single pneumatic air supply powers dozens of doors simultaneously. Each of these product lines has unique parts requirements and ordering specifications that cannot be treated like standard surface-mounted closer parts.

Browse the complete LCN parts catalog at SecurityParts.com for all Sentronic, SEH, Smoothee, SEM 7800, and Auto Equalizer components. For the full LCN catalog including surface-mounted and overhead concealed closers, browse the commercial door closer parts catalog.

The LCN Sentronic System: How Fire Door Hold-Open Works

The LCN Sentronic system is built on a fundamental fire code requirement: interior fire and smoke barrier doors must be self-closing (they must close when not held open), but code allows them to be held open by an electromagnetic device connected to the building's fire alarm system. When the fire alarm activates, the current to the holding mechanism is interrupted and the door closes automatically under its own closer spring force.

This is the core operating principle of all Sentronic products. The door is held open during normal building hours by electromagnetic force. When fire alarm current interrupts, the electromagnetic hold releases and the door closer drives the door shut. No battery backup is involved: the fail-safe condition is always the de-energized state, which is the door closed. A power outage automatically closes all Sentronic-held doors, which is the correct life safety behavior.

LCN Sentronic Series Overview: Which Product for Which Door

Sentronic Parts Reference: Voltage Selection and Key Replacement Components

The Most Critical Ordering Decision: 24V or 120V

Every Sentronic closer cylinder and track assembly is voltage-specific. Ordering the wrong voltage produces a unit that connects to the wrong wiring system and either fails to hold open (if 120V unit on 24V supply) or potentially damages the control board (if 24V unit on 120V supply). The voltage of the installed system must be confirmed before ordering any Sentronic replacement component.

The installed voltage is determined by the building's fire alarm or hold-open control panel. In most modern commercial installations, 24V DC or 24V AC is the standard because fire alarm systems operate at 24V. In older buildings, 120V wiring from the building's electrical system was used because early Sentronic systems predated 24V fire alarm standardization. When replacing a component in an older building, confirm at the existing wiring rather than assuming the voltage from the building's era.

The Solenoid Subassembly Rule

The solenoid in all LCN Sentronic closers and holders is not a separately replaceable component. This is the single most important parts fact about Sentronic systems that is not documented in any supplier catalog in buyer-facing format. When a Sentronic closer fails to hold open (door closes immediately even with power applied), the diagnosis often points to the solenoid. The correct replacement is the track assembly or cylinder subassembly that includes the solenoid, not a standalone solenoid coil.

The 4040SE-3038 track assembly is the replacement unit that resolves solenoid failures on the 4040SE, 4040SEH, 3130SE, 4010SE, and 4110SE. It is ordered with voltage specification. No standalone solenoid replacement kit exists for these models. Ordering a solenoid coil separately, as some buyers attempt, produces a part that cannot be field-installed without the complete subassembly.

4310HSA and 4410HSA Sentronic: High-Traffic Passage Closers

The LCN 4310HSA and 4410HSA Sentronic Series occupies a different application niche from the fire door hold-open Sentronic products. Where the 4040SE, 3130SE, and 2310ME are fire-coded products for doors that must be kept closed during fire events, the 4310HSA and 4410HSA are electronically controlled closers designed for easy passage through high-traffic doors in normal building operations.

The 4310HSA and 4410HSA use an electronic hold-open function that allows staff or residents to pass through a door without fighting the closer spring force on every passage. A credential event, push-button signal, or occupancy sensor can trigger the hold-open, and the door closes automatically after the hold-open period expires. This is the correct specification for pharmacy pass-through doors in hospitals, resident wing corridor doors in assisted living, and high-traffic interior doors where physical effort is a barrier for specific user populations.

Both the 4310HSA and 4410HSA are surface mounted. The 4310HSA mounts on the hinge (pull) side. The 4410HSA mounts on the top jamb (push side). Parts for these series include voltage-specific cylinder assemblies and switch assemblies consistent with the broader Sentronic family.

LCN SEH Series Holder: The Critical Installation Requirement

The LCN SEH Series (including the 4040SEH) is a holder only device with no closing mechanism. This distinction is the most important life safety fact about the SEH Series and is responsible for more non-compliant fire door installations than any other LCN specification error.

SEH vs 4040SE: The Missing Closer

The 4040SE is a complete closer and holder in one unit. The 4040SEH is a holder only. When the fire alarm de-energizes the SEH's holding mechanism, the door must be closed by a separate door closer mounted on the opposite side of the door from the SEH. Without this opposite-side closer, the door hangs open when the SEH releases. A fire door assembly on a smoke or fire barrier that does not self-close is a non-compliant assembly and can result in the Authority Having Jurisdiction (AHJ) requiring immediate correction.

SEH Mounting and Configuration

The SEH Series mounts on the hinge pull side or stop face push side. The non-handed arm (SEH-3077T, standard single 100-degree holder arm) can be combined with any 4040SE series track, providing flexibility in mounting position. The track roller (SEH-3034) is the low-friction roller assembly with a 1/4-inch shoulder dimension X. The track slider (SEH-168) is the alloy metal slider used in SE series tracks.

LCN SEM 7800 Series Magnetic Holders

The LCN Sentronic SEM 7800 Series are electrically controlled door-holding magnets that are categorically different from Sentronic closers. The magnet holds the door open through direct magnetic attraction to a ferrous armature plate mounted on the door face. When the fire alarm de-energizes the magnet, the door releases and a separate door closer drives it shut.

SEM 7800 Mounting Options

The SEM 7800 Series offers three mounting configurations to address different door and corridor geometries:

Floor mount: The magnet mounts on the floor directly below the door edge. The armature plate mounts on the bottom of the door. Floor mounting is the cleanest aesthetic solution because the magnet is not visible on the wall or door face when the door is open.

Surface wall mount: The magnet mounts on the wall adjacent to the door. The armature plate is on the door face at the same height. Surface wall mounting is the easiest to install but leaves the magnet body visible on the wall.

Recessed wall mount: The magnet is recessed into the wall with only the face plate visible. This provides the lowest-profile wall appearance while maintaining the magnetic holding function.

LCN 4210 and 4510 Smoothee: High-Security Closer Parts

The LCN 4210 and 4510 Smoothee Series are the surface-mounted high-security door closers in the LCN catalog. They are specified in correctional facilities, detention centers, psychiatric hospitals, and juvenile facilities where occupants may have motive and opportunity to defeat or damage door hardware.

The "Smoothee" designation, which has been part of the LCN naming convention for decades, refers to the smooth, tamper-resistant exterior of the closer body. Standard door closers have exposed adjustment valves, arm screws, and cover seams that provide leverage points for tampering. The Smoothee's design minimizes these attack surfaces.

4210 vs 4510 vs 2210

The 4210 is the standard high-security Smoothee, heavy-duty surface mounted with special components to minimize tampering and vandalism. The 4510 is the heavy-duty high-security version for applications requiring maximum closer durability alongside the tamper-resistant design. The 2210 is the overhead concealed version of the high-security closer, for applications where a concealed installation is preferred but still require tamper resistance. All three are Grade 1 and available in finishes appropriate for institutional environments.

Smoothee Arm and Valve Access

The Smoothee Series uses a restricted cover design that limits access to the adjustment valves and arm screw without special tools. This is intentional: easy valve access is the primary tampering vulnerability on standard door closers in correctional environments. When servicing a Smoothee in the field, confirm the correct tool is available before beginning work. Attempting to access valves or covers with standard tools risks damaging the tamper-resistant features that make the Smoothee appropriate for its specification environment.

LCN Auto Equalizer Operators: Pneumatic and Electric

The LCN Auto Equalizer operator lines serve a specific application: doors that need to assist manual opening without being fully automatic door openers. Where the Benchmark and Senior Swing operators open doors automatically when activated, the Auto Equalizer provides reduced opening force assistance using pneumatic or electric power. The result is a door that feels lighter to open without being power-operated in the sense that requires ADA guard rails or safety mats.

Pneumatic Auto Equalizer: 2610, 4810, 4820, 4840

The pneumatic Auto Equalizer series uses compressed air to equalize the door opening force. The 2610 is the most distinctive model: a single air supply unit that can power multiple doors simultaneously through pneumatic distribution lines. This multi-door capability makes the 2610 appropriate for large corridor projects where installing individual operators on each door would be prohibitively expensive.

The 4810 is the pneumatic series for primarily manual applications where occasional automatic assistance is needed. The 4820 is the low-energy ADA version providing controlled opening for accessible routes. The 4840 is the pneumatic multi-door solution for simultaneous control of several doors from a single air supply.

Electric Auto Equalizer: 4630 and 4640

The 4630 and 4640 use an electrohydraulic mechanism (motor-driven hydraulic pump) rather than compressed air. The 4630 allows manual opening to 170 degrees. The 4640 allows manual opening to 100 degrees.

Both the 4630 and 4640 are designed for doors up to 225 pounds and act as standard door closers in the event of power outage, maintaining the fail-safe closed behavior required on fire-rated egress doors. The 4630 and 4640 use a controller assembly (part 4640-3462 for the 4640) that manages the hydraulic operation and includes an on/off switch and hold-open adjustment.

For reveal depths between 4-1/2 inches and 8 inches, the 4630 requires the 4642 long arm. For reveal depths greater than 8 inches, consult the factory before ordering. This arm specification is distinct from all surface-mounted LCN closer arms and must be confirmed against the specific door reveal before any arm replacement order.

How to Identify the Correct Sentronic or Specialty Closer Before Ordering

Five pieces of information are needed before any Sentronic or specialty LCN parts order.

1. Series designation (4040SE, 4040SEH, 4310ME, 4410ME, 2310ME, 3130SE): On the label under the cover or on the cylinder body. This determines the parts catalog section.

2. Voltage (24V or 120V): At the wiring junction box or on the existing transformer. Voltage-specific components will not function if the wrong voltage is ordered.

3. Which component failed (track assembly, on/off switch, transformer, roller, slider): Track assembly failures: door does not hold even with power confirmed. Switch assembly failures: hold-open function cannot be tested or interrupted from the local switch. Roller failures: track noise or resistance on door swing.

4. For SEH: confirm opposite-side closer is present and UL-listed. Any SEH parts order should include verification that the opposite-side closer is still functional and compliant before the SEH is serviced.

5. For Smoothee: confirm available service tools before scheduling field work. The Smoothee's tamper-resistant design requires specific tools that may not be on a standard service truck.

Browse the LCN parts catalog at SecurityParts.com for all Sentronic, SEH, Smoothee, SEM 7800, and Auto Equalizer components. For the full LCN closer catalog including surface-mounted and concealed series, browse the commercial door closer parts catalog. For related exit device and alarm parts that appear on the same fire doors, browse exit alarm parts and exit device parts. Pre-order support is at 845-935-0301 or the contact page.

Related Parts and Products at Security Parts

Fire and smoke barrier doors that use LCN Sentronic or SEH holders also typically include exit devices, electric strikes for access-controlled fire door openings, and exit alarms on secondary egress doors.

For Von Duprin and Falcon exit device parts on fire-rated egress doors in the same building, browse the exit devices catalog. For Von Duprin Guard-X and Detex ECL exit alarm parts on fire door secondary exits, browse the exit alarms catalog. For Von Duprin electric strike parts on fire door frames with access control, browse the electric strikes catalog. For Schlage ND and ALX Series cylindrical lock parts on office and interior doors in the same facility, browse the cylindrical locks catalog. For Schlage L Series mortise lock parts on high-security entries in the same building, browse the mortise locks catalog.

Browse the complete all products and parts catalog to source LCN, Von Duprin, Schlage, Falcon, and Detex hardware across the complete facility in a single session.