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Product Introduction
When you are staring at a hydraulic power unit (HPU) on a dynamic positioning vessel and the pressure reading is drifting, you need a sensor that won’t lie to you. The KONGSBERG 4S12PLSH20BKM is that sensor. It is a heavy-duty pressure transmitter designed specifically for the harsh realities of the maritime industry, handling everything from seawater cooling loops to high-pressure hydraulic systems without blinking.This unit is built around a ceramic thick-film measuring cell, which is a smart design choice for resisting corrosion and abrasion compared to standard steel diaphragms. It outputs a standard 4-20 mA signal, making it plug-and-play with most PLCs and alarm monitoring systems (like K-Chief). In my experience, the “SH” designation in the model number usually implies a specific cable or housing configuration suited for wet environments, so you won’t have to worry about moisture ingress tripping your ground fault alarms.
Key Technical Specifications
| Parameter | Value |
|---|---|
| Pressure Range | 0 to 200 Bar |
| Output Signal | 4-20 mA (2-wire) |
| Accuracy | ±0.25% of Full Scale (FS) |
| Measuring Cell | Ceramic Thick-Film |
| Overpressure Limit | 2x Full Scale (400 Bar) |
| Supply Voltage | 10-30 V DC |
| Process Connection | G1/4″ or G1/2″ (Verify specific suffix) |
| Protection Class | IP65 / IP67 (Depending on connector) |
| Medium Temperature | -20°C to +80°C |
| Ambient Temperature | -40°C to +85°C |
| Material (Wetted) | Stainless Steel / Ceramic |
Application Scenarios & Pain Points
The real value of a sensor like the 4S12PLSH20BKM becomes obvious at 3 a.m. when the main engine lube oil pressure drops. If your sensor has a slow response time or drifts due to temperature changes in the engine room, the automation system might trigger a false shutdown. That costs thousands of dollars in off-hire time. This transmitter is designed to provide stable feedback to the safety system, ensuring the engine only stops when it absolutely has to.
- Marine Hydraulics: Perfect for monitoring steering gear pumps where pressure spikes are common. The ceramic cell handles the shock better than thin metal diaphragms.
- Ballast & Bilge Systems: Needs to handle dirty water and sludge without clogging or corroding the sensing element.
- Subsea Monitoring: Often used in ROV (Remotely Operated Vehicle) power packs where reliability is non-negotiable.
- What if the cable gets wet? The “SH” variant typically comes with a robust cable gland or connector, but honestly, always check the IP rating against your specific deck exposure.
Field Note: I once saw a generic pressure transmitter fail on a crane vessel because the vibration cracked the solder joints inside. The Kongsberg 4S series is potted (filled with resin) to prevent exactly that kind of vibration damage.
Quality Control Process (SOP Transparency)
We don’t just look at the box and ship it. Here is exactly what we do with a 4S12PLSH20BKM before it leaves our bench:
- Inbound Inspection: We verify the laser engraving on the stainless steel housing matches the packing list. We check for the Kongsberg hologram on the label to rule out fakes.
- Visual Check: We look for bent pins on the connector and ensure the cable jacket isn’t brittle or cracked (common in old stock).
- Live Functional Test: We mount it on our dead-weight tester. We apply 0 Bar, 100 Bar, and 200 Bar. We measure the mA output with a Fluke 754 process calibrator. It must read 4.00 mA, 12.00 mA, and 20.00 mA (±0.05 mA tolerance).
- Insulation Test: We use a 100V megger to ensure there is no leakage between the housing and the signal wires. It must read >100 MΩ.
- Final Pack: We seal it in an anti-static bag with a desiccant pack.
Installation Pitfalls Guide (“Lessons Learned” Voice)
I’ve seen too many of these come back as “defective” when they were actually installed wrong. Don’t be that guy.
- Teflon Tape in the Wrong Place: ❗ Never wrap Teflon tape over the pressure port hole. If tape gets inside the ceramic sensor, it ruins the diaphragm instantly. Wrap the threads, but leave the tip clean.
- Over-torquing: These have a specific installation torque (usually around 20-40 Nm depending on the thread). If you crank it down with a 2-foot breaker bar because “it feels loose,” you will crack the housing. Use a torque wrench.
- Ground Loops: If your 4-20 mA signal is noisy, check your grounding. The transmitter housing must be grounded, but don’t ground both ends of the cable if your PLC is already grounded. That creates a loop that looks like signal noise.
- Cable Gland Tightness: If you are using the cable version, make sure the strain relief is tight. If the cable pulls out, seawater wicks right up the copper strands into your junction box.
