Cart (
Overview
The Graviner MK-5 oil mist detector is a cornerstone of crankcase safety on merchant vessels worldwide — installed on main engines and auxiliary diesels across tankers, bulk carriers, container ships, and offshore platforms to provide continuous monitoring of crankcase oil mist concentrations. It remains one of the most widely recognised oil mist detection systems in the marine industry, and for vessels where the MK-5 is still the installed system, keeping it operational is not optional. Class societies require it. Flag states enforce it. And chief engineers depend on it to protect against one of the most catastrophic failure modes in marine engine operations: a crankcase explosion.
The Graviner MK-5 Oil Mist Detector Main PCB Assembly is a refurbished replacement main printed circuit board for the MK-5 oil mist detection system. As the central processing and control board of the MK-5, the main PCB is the component that receives input signals from the detector’s sampling circuit, processes oil mist concentration data from each sample point, drives the alarm relay outputs, and manages the system’s operational logic. When the main PCB fails, the entire MK-5 system fails — the detector can no longer process sample data, generate alarms, or communicate fault status. The vessel is left without functional crankcase oil mist protection until the PCB is restored or replaced.
What distinguishes this component from generic alternatives is the combination of manufacturer-referenced compatibility and tested refurbished condition. The MK-5 main PCB is a precision assembly — the relay configurations, input channel assignments, alarm threshold logic, and output characteristics are specific to the MK-5 platform and cannot be replicated by a generic substitute board. For marine superintendents, chief engineers, and procurement teams who need to restore a failed MK-5 system with confidence in component integrity and system compatibility, this refurbished OEM-referenced main PCB assembly is the correct procurement choice.
Key Features
Central Processing and Control for the Graviner MK-5 System
The main PCB is the operational brain of the MK-5 oil mist detector — the board that processes oil mist concentration signals from the sampling circuit, evaluates alarm thresholds across multiple sample channels, and activates the alarm relay outputs that trigger engine slowdown or shutdown responses. Every function the MK-5 performs passes through this board. A failed main PCB does not produce a degraded system — it produces a non-functional system. Replacing it with the correct OEM-referenced assembly is the only reliable path to restoring full MK-5 system operation.
Multi-Channel Sample Point Management
The MK-5 main PCB manages the sequential sampling of multiple crankcase sample points — rotating through each detector position in sequence to monitor oil mist concentration levels across the entire engine crankcase. The “SAMPLE NUMBER” indicator visible on the board’s integrated display panel confirms active sample channel cycling during operation. This multi-channel management function is what allows the MK-5 to provide comprehensive crankcase monitoring across all engine bays from a single detector unit, and it is governed entirely by the main PCB’s control logic.
Integrated Alarm Level Display and Relay Logic
The main PCB incorporates the alarm level display and relay output logic visible in the board’s integrated panel section — the “HIGH/CAUTION OIL ALARM LEVEL” indicator array and associated relay board. This section of the PCB manages the graduated alarm response: caution level alarms that alert the crew to an elevated oil mist condition, and high-level alarms that trigger automatic engine protection responses. The relay outputs connect to the vessel’s engine control and alarm systems, making the main PCB the link between the MK-5 detector and the engine’s automated safety response chain.
Capacitor and Power Supply Circuit Array
The main PCB carries a substantial array of electrolytic capacitors and power conditioning components — visible across the left section of the board in the product image. These components maintain stable power supply to the MK-5’s processing circuits and protect the detector’s signal processing from voltage transients and power fluctuations common in engine room electrical environments. Capacitor degradation is one of the most common causes of MK-5 main PCB failure in long-service installations, making a refurbished board with inspected and replaced capacitors a more reliable maintenance outcome than attempting individual component-level repair on a degraded original board.
Direct Plug-In Replacement for MK-5 Systems
The main PCB assembly is designed as a direct replacement for the MK-5 system’s existing main board — retaining the same connector layout, mounting configuration, and interface architecture as the original. This means the replacement board installs into the existing MK-5 enclosure without modification to the system wiring, sampling circuit connections, or alarm relay outputs. For vessels carrying out an MK-5 main PCB replacement during a port call or drydock maintenance window, a direct-fit replacement board minimises the time the system spends out of service during maintenance.
Refurbished Condition — Inspected, Repaired, and Tested
The assembly is supplied in refurbished condition — inspected, component-checked, and functionally tested before supply. For the main PCB of a safety-critical oil mist detection system, the distinction between tested refurbished and untested used condition carries real operational weight. An untested used main PCB of unknown history may carry latent faults in its capacitors, relay contacts, or signal processing circuits that only manifest under operating conditions — after installation. A tested refurbished board provides documented functional assurance appropriate for the central control component of a marine crankcase safety system.
Technical Specifications
Component: Main PCB Assembly
Compatible System: Graviner MK-5 Oil Mist Detector
Manufacturer: Graviner (Kidde / UTC Fire & Security)
Model: MK-5
Description: MK-5 Oil Mist Detector Main PCB Assembly
Board Type: Main control and processing PCB with integrated alarm relay section
Key Functions: Sample channel management, oil mist alarm processing, relay output control
Category: PCBs & Electrical Components
Condition: Refurbished
Benefits
Restores complete MK-5 system functionality after main PCB failure. A failed main PCB takes the entire MK-5 system offline — not just a single function. There is no partial operation with a failed main board; the system cannot sample, process, alarm, or communicate until the PCB is restored. Replacing the main PCB assembly with the correct OEM-referenced refurbished board returns the MK-5 to full operational status: active sample cycling, graduated alarm outputs, and connected engine protection relay responses — all restored in a single component replacement.
Maintains class survey compliance for crankcase oil mist detection requirements. Classification society surveyors verify that crankcase oil mist detection systems are operational and correctly configured during machinery surveys. An MK-5 system with a failed main PCB — or one that has been bypassed or isolated to manage a persistent fault condition — will not satisfy survey requirements. Having the main PCB restored before a scheduled survey removes a deficiency risk that could result in a class condition, a port state control observation, or a required rectification before the vessel can sail.
Eliminates the risk of operating with bypassed crankcase protection. When the MK-5 main PCB fails and no replacement is immediately available, the practical pressure to bypass or isolate the system to clear the fault alarm from the engine control panel is real — and the safety consequence of doing so is equally real. A vessel operating with a bypassed oil mist detector has no early warning capability for a developing crankcase oil mist condition. Maintaining a correctly functioning main PCB is the only reliable alternative to that situation.
Cost-effective restoration for long-service MK-5 installations where new OEM boards may be unavailable. The MK-5 has been in service for decades, and new OEM main PCB assemblies for older system variants are not always available through standard distribution at a practical price and lead time. A tested refurbished main PCB assembly sourced through a specialist marine safety equipment supplier provides a functionally equivalent restoration at a cost and availability profile that supports active vessel maintenance planning rather than extended system downtime.
Who It’s For
The Chief Engineer Facing a Failed MK-5 Before a Class Survey
The MK-5 on your main engine has gone offline — the system is showing a persistent fault that your diagnostic check has traced to the main PCB. You’ve got a class machinery survey scheduled in the next port and the last thing you need is the surveyor finding your crankcase oil mist detector non-operational or bypassed. You need the correct main PCB assembly confirmed compatible with your MK-5 variant, available on a lead time that fits your port call window, and supplied in tested condition so you’re not troubleshooting a second fault after installation.
The Technical Superintendent Managing Fleet MK-5 Spare Parts Inventory
You manage a fleet with multiple vessels carrying Graviner MK-5 oil mist detectors — some of them 15 or 20 years into their service life. Main PCB failures are an eventuality you plan for, not a surprise, and maintaining a spare main PCB assembly in the vessel’s onboard spare parts inventory — or a centrally held fleet spare — is a straightforward way to ensure that when a failure occurs, restoration is measured in hours, not weeks of procurement lead time. A refurbished OEM-referenced main PCB assembly sourced through a reliable specialist supplier is the right component for that inventory position.
Possible Applications
- Main engine crankcase protection on ocean-going vessels — Main PCB replacement for MK-5 systems installed on two-stroke slow-speed and four-stroke medium-speed main propulsion engines aboard tankers, bulk carriers, container ships, and general cargo vessels
- Auxiliary diesel generator engine rooms — MK-5 system restoration on generator engine installations where crankcase oil mist detection is required by class rules on engines above the applicable bore diameter threshold
- Offshore platform and FPSO machinery spaces — Main PCB spare parts sourcing for MK-5 installations on offshore diesel power generation and propulsion systems where system downtime has direct operational cost consequences
- Drydock and class renewal survey preparation — Pre-survey MK-5 main PCB replacement during planned drydocking to restore systems that have developed faults during the preceding service period and need to be survey-ready before the class inspection
- Fleet onboard spare parts provisioning — Held spare main PCB assembly for ship management companies maintaining MK-5 spare parts inventories across managed fleets, ensuring fast onboard restoration capability without waiting for international courier procurement
- Naval and coast guard vessel engine room maintenance — Main PCB sourcing for naval vessel propulsion and auxiliary diesel installations where Graviner MK-5 systems are part of the installed machinery protection suite
- Marine engineering service companies — Component sourcing for MK-5 system overhaul, repair, and maintenance contracts carried out on behalf of vessel owners and ship managers under service agreement
Trust and Certifications
Graviner MK-5 — Decades of Marine Engine Safety
Graviner (now operating under Kidde / UTC Fire & Security) developed the MK-5 oil mist detector as part of a product line that has been at the centre of marine crankcase safety for over 40 years. The MK-5 platform’s longevity in service — still actively maintained on thousands of vessels worldwide — is a reflection of its established reliability and the continued classification society recognition of the system as a compliant crankcase oil mist detection solution. Sourcing spare components for the MK-5 from a specialist marine safety equipment supplier with confirmed access to OEM-referenced refurbished stock is the appropriate maintenance standard for a system of this safety significance.
IMO Resolution A.1050(27) — Crankcase Oil Mist Detector Performance Standards
IMO Resolution A.1050(27) establishes performance and installation requirements for crankcase oil mist detectors on seagoing vessels. Vessels where the MK-5 is installed under this resolution are required to maintain the system in operational condition — a requirement that applies regardless of the system’s age. Main PCB replacement that restores the MK-5 to full operational status supports the vessel’s continued compliance with the IMO resolution requirements that form the regulatory basis for the oil mist detection installation obligation.
Classification Society Machinery Survey Requirements
All major classification societies — including Lloyd’s Register, DNV, Bureau Veritas, ClassNK, and ABS — require crankcase oil mist detectors on engines above specified bore diameters to be maintained in operational condition and verified during periodic machinery surveys. A non-operational MK-5 system due to a failed main PCB is a class deficiency. Restoring the system with the correct OEM-referenced main PCB assembly supports the vessel’s ability to present the oil mist detection system in survey-ready condition.
Refurbished and Tested — Functional Verification Before Supply
The main PCB assembly is supplied in refurbished condition, inspected and functionally tested before supply. Given that the main PCB carries the MK-5 system’s entire alarm processing and relay output logic, functional testing before supply is the minimum acceptable assurance standard for this component. A board supplied without functional verification introduces the risk of a second failure event during installation — extending system downtime and adding unnecessary troubleshooting complexity to what should be a straightforward component replacement.
Supplied by Alright Engineering Solutions
The Graviner MK-5 Main PCB Assembly is supplied through Alright Engineering Solutions Pte. Ltd., a specialist distributor of marine safety equipment, gas detection systems, and engine room safety components based in Singapore. Alright Engineering Solutions provides spare parts sourcing and procurement support for marine oil mist detection, gas detection, and fire safety systems across the Singapore and regional market.
Accessories and Variants
Additional Graviner MK-5 System Spare Components
Alright Engineering Solutions can assist with sourcing a full range of Graviner MK-5 system spare parts — pressure switch assemblies, detector sampling heads, relay boards, power supply components, and associated MK-5 system spares — for vessel maintenance programmes and fleet spare parts provisioning. Contact our team with your MK-5 system spare parts requirements for availability enquiry and quotation.
Graviner MK-4 and MK-6 System Components
For vessels equipped with related Graviner oil mist detector variants — including the MK-4 and the later MK-6 — Alright Engineering Solutions can provide guidance on available spare parts and refurbished component options for related Graviner system platforms.
Related Marine Engine Room Safety Products
Graviner MK-5 Pressure Switch Assembly — Refurbished pressure switch for the MK-5 oil mist detector sampling circuit airflow monitoring function
GTYQ-DX 102 Fixed Combustible Gas Detector — Fixed gas detection point with 4–20mA and RS485 output for engine room hydrocarbon monitoring
GX-8000 Sample Draw Multi Gas Monitor — Portable marine sample draw multi-gas monitor for confined space entry and engine room gas surveys
Salwico CS3000 System Spare Parts — Refurbished display LCD PCBs and system components for Salwico CS3000 fixed gas and fire detection systems
Get in Touch
If you need to source the Graviner MK-5 Oil Mist Detector Main PCB Assembly for a vessel maintenance requirement — whether for an immediate system restoration, an upcoming drydock programme, or fleet spare parts provisioning — contact Alright Engineering Solutions to confirm availability and request a formal quotation.
Our team can also assist with sourcing additional MK-5 system spare parts and related marine engine room safety components for your vessel or fleet maintenance programme.
📍 3791 Jalan Bukit Merah #06-01, E-Centre @ Redhill, Singapore 159471
