Riken Keiki DC-3A Slop Indicator Set

RIKEN KEIKI MODEL DC-3A SLOP INDICATOR SET

The Riken Keiki Model DC-3A Slop Indicator Set (Part Number: M-73) is a specialized, intrinsically reliable marine measurement instrument engineered for precise liquid level and oil-water interface surface detection. Primarily deployed on crude oil tankers, chemical carriers, and offshore processing units, the DC-3A facilitates accurate detection of slop tank stratification, bilge holding interface boundaries, and ballast water surface levels.

Manufactured in Japan under rigorous marine safety and quality control standards, the unit integrates heavy-duty sensing electrodes with high-visibility white measuring tape. Certified by Nippon Kaiji Kyokai (ClassNK) under Type Test Certificate 8IT639, the DC-3A is built to endure harsh marine environments, extreme vibration, salt-spray exposure, and hazardous atmospheric zones.

Key Features

1. Type-Approved Marine Reliability: Fully certified by Nippon Kaiji Kyokai (ClassNK Type Test No. 8IT639) for shipboard environmental compliance and regulatory MARPOL Annex I monitoring workflows.
2. High-Conductivity Boundary Discrimination: Rapidly differentiates between hydrocarbon phases and conductive water layers, providing instant signal feedback at the interface line.
3. Corrosion-Resistant Sensing Electrode: Constructed with specialized marine alloys and chemical-resistant insulation designed to resist sour crude, oily slops, and chemical wash solutions.
4. Graduated High-Visibility White Tape: Heavy-duty, hydrocarbon-resistant tape assembly allows direct mechanical depth reading alongside electrical signal verification.
5. Robust, Compact Deck-Ready Enclosure: Weighing 3.110 kg, the set is portable and ruggedized for rough sea handling, closed-tank sampling standpipes, and vapor-lock valves.

Applications

• Tanker Slop Tank Monitoring: Measuring settling tank oil-water interface prior to decanting or discharging overboard via the ODME system.
• Bilge Water Holding Tanks: Real-time level and separation surface checks to safeguard 15 ppm bilge separator operation.
• Ballast & Void Space Inspection: Detecting unexpected hydrocarbon ingress or sea-chest flooding in double-hull structures.
• Offshore FPSO & Platform Storage Cells: Tracking hydrocarbon emulsion layers in separation vessels and storage skids.
• Industrial Marine Waste Processing: Wastewater collection, skimmer sumps, and refinery holding tanks.

Compatible Systems

• Riken Keiki Marine Gas & Tank Level Monitoring Frameworks
• Standard Marine Vapor Lock Valves (1-inch, 2-inch standard flange adapters)
• ODME (Oil Discharge Monitoring & Control) associated slop settling tanks
• Deck Standpipe & Ullage Port sounding setups

Part Number Cross-References

• Riken Keiki: DC-3A, DC3A
• Sato Parts: M-73
• Marine Inventory Ref / SKU: 79786, 8IT639

Chief Engineer’s Operational Notes:

Electrode Cleaning & Hydrocarbon Film Buildup:

Heavy fuel oil (HFO) and crude oil residues will eventually coat the sensing head, causing an insulating barrier that prevents water conductivity detection. Always flush the probe head with an approved solvent (electro-cleaner or light distillate) after each sounding routine. Never use abrasive metal wire brushes on the electrode tip.

Grounding & Static Discharge Precaution:

When lowering the DC-3A probe through an open ullage port or vapor lock on an un-inerted or volatile tank, ensure the bonding lead is firmly clamped to the vessel’s bare steel hull/tank structure before opening the valve. This dissipates any static charge generated along the sounding tape.

Verification Before Discharge:

Prior to starting slop tank decanting through the ODME, take three separate interface soundings across forward, middle, and aft deck ports (or correct for ship’s trim/list using the tank calibration table). A 10 cm sounding error on a large tanker slop tank can cause significant oil carry-over and trigger an emergency ODME overboard shutdown.

Frequently Asked Questions

How does the Riken Keiki DC-3A detect the oil-water interface?

The DC-3A utilizes the differential electrical conductivity between water and oil. When the electrode encounters the water layer beneath the non-conductive hydrocarbon layer, the circuit completes, immediately providing an audible/visual signal on the indicator unit, allowing the operator to read the exact depth on the graduated tape.

Is the Riken Keiki DC-3A approved for use under ClassNK rules?

Yes. The DC-3A Slop Indicator Set holds Nippon Kaiji Kyokai (ClassNK) certification under Type Test Number 8IT639, meeting standard international maritime safety requirements for liquid level surface detection on ships.

Can this unit be used with corrosive chemicals or solvent tanks?

The sensor head and tape materials are rated for standard hydrocarbon slop mixtures, seawater ballast, and routine tank-cleaning wash waters. For aggressive acids or specialized chemical tankers (IBC Code cargoes), material chemical compatibility must be verified prior to immersion.

What maintenance is required for reconditioned DC-3A units?

Routine maintenance involves checking tape graduations for mechanical wear, inspecting the terminal connections at the reel hub, verifying ground wire continuity, and performing zero-point continuity checks with saline solution before critical soundings.