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Overview
The Graviner Mark 5 Oil Mist Detector is fundamentally an optical instrument. It measures oil mist concentration in the crankcase atmosphere by passing a beam of light through the sampled air and measuring how much of that light reaches the photocell on the other side. The light source assembly is the component that generates this measurement beam — and without a functioning light source, the MK-5’s optical detection system is simply inoperative. No light beam means no optical measurement, no concentration data, and no alarm capability, regardless of the condition of every other component in the detector. A degraded or failed light source assembly is therefore one of the most direct paths to complete crankcase detection system failure on a vessel where the MK-5 is the installed protection device.
The Graviner Mark 5 Light Source Assembly (Part No. 45626-120) is a refurbished replacement light source assembly for the Graviner MK-5 Oil Mist Detector. As visible in the product image, the assembly consists of a threaded body — designed to mount into the MK-5 detector’s optical chamber — with an integrated light source element and retention wiring, supplied as a complete, ready-to-fit replacement unit. Fitting this assembly restores the MK-5’s optical measurement beam and, with it, the detector’s ability to continuously monitor crankcase oil mist concentration and generate alarm outputs when concentration thresholds are exceeded.
The specific differentiator here is spectral and intensity specification. The MK-5’s optical measurement system is calibrated against a specific light source output — the wavelength, intensity, and beam geometry of the light source assembly are integral to the detector’s concentration measurement accuracy and alarm threshold calibration. Part No. 45626-120 is the OEM-referenced designation for this light source assembly within the Graviner Mark 5 product family, confirming that the replacement assembly matches the optical specification the MK-5’s measurement circuit was designed and calibrated around — not a generic lamp or LED of broadly similar output.
Key Features
Integrated Light Source Element with Threaded Mounting Body — Complete Assembly Replacement
The light source assembly is supplied as a complete unit — threaded mounting body, light source element, and retention wiring — allowing direct replacement within the MK-5 detector’s optical chamber without requiring separate lamp or body sourcing. The threaded body design ensures precise and repeatable positioning of the light source within the optical chamber, maintaining the beam geometry that the photocell and measurement circuit depend on. Assembly-level replacement simplifies the repair procedure and eliminates the alignment uncertainty that would exist if the light source element were replaced separately within the existing body.
OEM Part Number 45626-120 — Confirmed Optical Specification for MK-5 Measurement System
The 45626-120 part number is the manufacturer’s own reference for this light source assembly within the Mark 5 detector. In an optical oil mist detector, the light source is not simply a lamp that needs to produce visible light — it must produce light at the correct wavelength, intensity, and beam geometry for the detector’s specific optical measurement architecture. The MK-5’s alarm threshold calibration is set against a specific light source output: a substitute lamp or assembly with different optical characteristics will produce a detector that either over- or under-reports oil mist concentration relative to its type-approved alarm thresholds. The OEM part number is the only reliable confirmation that the replacement assembly matches the detector’s original optical specification.
Refurbished Condition — Inspected and Assessed Before Supply
The light source assembly is supplied in refurbished condition, inspected for physical integrity and operational condition before dispatch. For an optical component that must produce consistent light output throughout its service life to maintain detector measurement accuracy, condition assessment before supply is the appropriate quality standard. Refurbished OEM-referenced availability also addresses the practical supply chain challenge for MK-5 light source assemblies — new OEM stock for specific MK-5 variants is frequently discontinued or on extended lead times, and specialist marine safety equipment suppliers with access to inspected refurbished assemblies provide the most reliable procurement route for long-service MK-5 installations.
Directly Addresses the Root Cause of MK-5 Optical Measurement Failure
Light source failure — through element burnout, degraded output intensity, or physical damage to the assembly — is one of the most common root causes of MK-5 optical measurement failure. A detector presenting persistent low-reading fault conditions, erratic concentration values, or complete loss of optical signal frequently traces back to a degraded light source assembly rather than a fault in the detector’s electronic or airflow systems. Replacing the light source assembly as a targeted component repair resolves the root cause of the optical measurement failure without requiring replacement of the broader detector optical system or the complete detector unit.
Retention Wiring Prevents Assembly Loss During Maintenance
As visible in the product image, the light source assembly includes a retention wire loop — a practical design detail that prevents the assembly from being accidentally dropped or lost into the detector enclosure during removal and replacement. In the confined space conditions common to marine engine room maintenance, retaining small precision components during removal is a straightforward but genuinely useful design feature that reduces the risk of a maintenance procedure being complicated by a dropped or lost component.
Technical Specifications
Component: Light Source Assembly
Part Number: 45626-120
Compatible System: Graviner Mark 5 (MK-5) Oil Mist Detector
Manufacturer: Graviner (Kidde / Carrier Global)
Model: MK-5
Description: MK-5 Oil Mist Detector Light Source Assembly
Assembly Type: Complete unit — threaded mounting body, light source element, retention wiring
Mounting: Threaded body for direct installation into MK-5 optical chamber
Function: Generates the optical measurement beam within the MK-5 detection chamber
Condition: Refurbished
Benefits
Restores the MK-5’s optical measurement capability — and with it, the entire detection and alarm function. The light source assembly generates the beam that makes oil mist concentration measurement possible. Without a functioning light source, no other component in the MK-5 detection chain — photocell, electronics, fan, solenoid valve — can contribute to a valid measurement or alarm output. A single assembly replacement restores the complete optical measurement function and returns the detector to fully operational status.
Maintains type-approved alarm threshold accuracy by preserving the detector’s original optical specification. The MK-5’s alarm thresholds are calibrated against the optical characteristics of the original OEM light source assembly. Replacing a failed assembly with the correct OEM-referenced 45626-120 unit ensures the detector’s measurement and alarm performance remains consistent with its type-approved specification — not recalibrated against the different optical output of a substitute assembly. This is the specific reason why part number confirmation matters for light source replacement, not just dimensional fit.
Resolves optical fault conditions without requiring replacement of the broader optical system. MK-5 detectors presenting optical fault alarms, persistent low-signal readings, or erratic concentration values that trace back to a degraded light source can be returned to full operation with light source assembly replacement alone — without disturbing or replacing the photocell assembly, detection chamber, or detector electronics. Targeted light source replacement is the correct repair approach for optical faults that are confirmed to originate at the source rather than at the detection side of the optical circuit.
OEM part number supports ISM Code maintenance documentation and class survey traceability. The 45626-120 OEM part number provides the component identity reference required for maintenance log entries, spare parts records, and class survey documentation. For an optical component in a crankcase safety detection system — where the light source’s specification directly affects the detector’s type-approved measurement accuracy — OEM part number traceability is the appropriate maintenance documentation standard.
Refurbished availability bridges the OEM supply gap for mature MK-5 installations. New OEM light source assembly stock for specific MK-5 variants is frequently discontinued or available on extended lead times through standard OEM channels. Specialist marine safety equipment suppliers with access to inspected refurbished OEM-referenced assemblies provide the supply chain solution that keeps long-service MK-5 detectors optically operational without waiting on procurement timelines that don’t fit the vessel’s maintenance schedule.
Who It’s For
The Ship’s Chief Engineer Investigating an MK-5 Optical Fault Alarm
The MK-5 on one of your crankcase detection points is logging an optical fault — persistent low signal, erratic concentration readings, or complete loss of optical measurement. After ruling out photocell and electronic faults, inspection of the light source assembly reveals a failed or degraded element. You need the correct OEM-referenced replacement — Part No. 45626-120 — confirmed and sourced in time to restore detector operation within your vessel’s port call or maintenance window. You need a supplier who can confirm availability and provide the assembly in inspected refurbished condition with the documentation your maintenance records require.
The Technical Superintendent Planning Proactive MK-5 Optical Component Replacement
You manage planned maintenance across a fleet of vessels with Graviner Mark 5 detectors approaching 15 to 20 years of service. Light source assembly degradation — element output reduction over operating hours, physical deterioration of the assembly body — is a predictable age-related failure mode in long-service MK-5 installations. Rather than waiting for in-service optical failures, you want to carry out proactive light source assembly replacement during the next drydock cycle across detectors that have accumulated significant operating hours. You need a specialist supplier who can provide confirmed OEM-referenced MK-5 light source assemblies in refurbished condition across the quantities needed for a fleet replacement programme.
The Marine Equipment Service Engineer Carrying Out MK-5 Optical System Overhauls
You service Graviner Mark 5 detectors under contract, and optical system overhaul — including light source assembly inspection and replacement where output is degraded — is a standard element of a thorough MK-5 service. You need a consistent source of OEM-referenced 45626-120 light source assemblies in inspected refurbished condition to maintain your service stock and support your overhaul contract schedule. You need a supplier who understands the MK-5 optical system, can confirm assembly compatibility with the specific detector variant, and provides the component documentation your service records require.
Possible Applications
- Bulk carriers and general cargo vessels — Light source assembly replacement to resolve MK-5 optical fault conditions and restore continuous crankcase oil mist concentration monitoring on vessels with medium-speed and slow-speed diesel main engines
- Tankers and chemical carriers — Emergency and planned light source replacement to maintain MK-5 optical measurement integrity on vessels where crankcase explosion risk management is a core element of engine room safety management
- Container ships and ro-ro vessels — Rapid optical fault repair during port calls to restore MK-5 detection capability without requiring complete detector replacement on high-utilisation vessels with tight maintenance windows
- Offshore support vessels and platform supply vessels — Emergency light source assembly sourcing for MK-5 detectors on offshore vessels operating in locations where standard OEM supply lead times are not compatible with the vessel’s operational schedule
- Cruise ships and passenger vessels — Planned and emergency MK-5 light source replacement to maintain crankcase detection system optical integrity on vessels subject to intensive safety scrutiny from flag state and port state control authorities
- Drydock and ship repair facilities — Proactive light source assembly replacement during class renewal surveys and scheduled drydocking as part of systematic MK-5 optical system overhaul programmes
- Marine safety equipment service contractors — Light source assembly stock maintenance for MK-5 optical fault diagnosis, overhaul, and repair contracts across Singapore and the regional market
Trust and Certifications
Graviner Mark 5 — The Industry Standard for Marine Crankcase Oil Mist Detection
The Graviner Mark 5 holds type approvals from all major classification societies — Lloyd’s Register, DNV, Bureau Veritas, American Bureau of Shipping, and ClassNK — and has been the de facto standard for marine crankcase oil mist detection for several decades. The MK-5’s optical measurement architecture — which depends on the light source assembly generating the correct measurement beam — is the foundation of the detector’s type-approved performance. Maintaining the MK-5 with OEM-referenced light source assemblies that match the detector’s original optical specification preserves that type-approved measurement accuracy and the vessel’s compliance with its class society’s crankcase protection requirements.
Refurbished and Inspected — Optical Condition Assessed Before Supply
The light source assembly is supplied in refurbished condition, inspected for physical integrity and operational condition before supply. For an optical component within a crankcase safety detection system — where the light source’s output specification directly affects the accuracy of the detector’s oil mist concentration measurements — condition assessment before supply is the appropriate quality standard. The refurbished designation reflects the practical supply chain reality for mature MK-5 variants: new OEM light source assembly stock is frequently discontinued, and specialist suppliers with access to inspected refurbished OEM-referenced assemblies provide the most reliable procurement route for long-service MK-5 installations.
Supplied by Alright Engineering Solutions
The Graviner Mark 5 Light Source Assembly (Part No. 45626-120) is supplied through Alright Engineering Solutions Pte. Ltd., a Singapore-based specialist supplier of marine safety and gas detection equipment and spare components. Alright Engineering Solutions supports vessel operators, ship management companies, and marine service contractors with MK-5 spare parts sourcing, availability enquiries, and procurement assistance across Singapore and the regional market.
Accessories and Variants
Complete Graviner Mark 5 Optical System Spare Parts
A thorough MK-5 optical system overhaul addresses both the light source and photocell sides of the optical measurement circuit. Alright Engineering Solutions can assist with sourcing the Graviner Mark 5 Photocell Housing (Part No. 45626-122) alongside the light source assembly — providing a consolidated optical system overhaul procurement option. Contact our team with your complete MK-5 optical component requirements for availability confirmation and quotation.
Related MK-5 Spare Components Available from Alright Engineering Solutions
Graviner Mark 5 Photocell Housing (Part No. 45626-122) — Refurbished replacement optical assembly enclosure — the photocell-side counterpart to this light source assembly
Graviner Mark 5 Solenoid Valve (Part No. 27481-953) — Refurbished replacement electromechanical airflow control valve for MK-5 sampling and reference circuit switching
Graviner Mark 5 Fan Assembly — Refurbished replacement centrifugal blower unit restoring active crankcase atmosphere sampling
Graviner Mark 5 Power Supply Select Card (Part No. 39832-704) — Refurbished replacement power supply PCB with 115V/220V/230V/240V voltage selection
Graviner Mark 5 Toroid (Part No. 44211-115) — Refurbished replacement inductive signal processing component for MK-5 detection circuit
Graviner Mark 5 Locating Spigot (Part No. 23617-403) — Refurbished replacement precision locating component for MK-5 detector assembly alignment
Get in Touch
If you need to source the Graviner Mark 5 Light Source Assembly (Part No. 45626-120) for an optical fault repair, planned overhaul, or fleet spare parts programme — contact Alright Engineering Solutions to confirm availability and request a formal quotation.
Our team can also support sourcing of a complete MK-5 optical system spare parts list — light source assemblies, photocell housings, and associated optical components — for comprehensive detector overhaul programmes across single vessels or managed fleets.
📍 3791 Jalan Bukit Merah #06-01, E-Centre @ Redhill, Singapore 159471
