ETO ENGINEER

The SCR system (Selective Catalytic Reduction) for marine diesel engines is used to reduce nitrogen oxide (NOx) emissions in order to comply with #MARPOL Annex VI (Tier II, Tier III) requirements. How #SCR Works on Marine Engines 1. Exhaust gas formation The engine produces exhaust gases with a high concentration of #NOx, especially at high loads. 2. Reagent injection A water-based urea solution (#AUS 40 or AdBlue/AUS 32) or ammonia is injected into the exhaust stream before the catalyst. • On ships, AUS 40 (40% urea solution) is most commonly used. 3. #Urea decomposition At high temperatures (around 300–400 °C), urea decomposes and releases #ammonia (NH₃) 4. Catalytic reaction Inside the #catalyst, ammonia reacts with NOx, converting it into nitrogen (N₂) and water (H₂O): • 4NO + 4NH₃ + O₂ → 4N₂ + 6H₂O • 6NO₂ + 8NH₃ → 7N₂ + 12H₂O 5. Clean exhaust NOx emissions are reduced by 70–95%, depending on system design and operating conditions. Main Components of a Marine SCR System • Dosing system: pumps, lines, and nozzles for urea injection. • Hydrolysis/mixing unit: ensures evaporation and proper mixing of reagent with exhaust gases. • Catalyst block: ceramic or metallic honeycomb coated with #catalyst materials (V₂O₅, TiO₂, WO₃, etc.). • Control system (PLC/controller): adjusts urea dosing according to #engine load and NOx levels. • #Sensors: temperature, pressure, #NOx (before and after SCR), NH₃ slip sensor. • AUS 40 storage tank: equipped with heating and filtration system. Important Aspects of SCR Operation on Ships • Exhaust gas temperature must be at least 250–300 °C for proper urea decomposition. • At low engine loads, SCR efficiency decreases. • The quality of AUS 40 is critical—impurities can clog injectors and the catalyst. • #Ammonia slip (unreacted NH₃ passing through) must be monitored and kept within limits. • Catalyst has a limited lifetime (typically 15,000–20,000 operating hours) and requires periodic regeneration or replacement. ⚠️ More information is available in our private channel ➡️ Marine Engineering Manuals ⭐️

Deca Classic battery charger. • #Eff. (Effective) – this is the effective current value, meaning the RMS (root mean square) value. It corresponds to the real equivalent #DC current that actually charges the battery. • #Arith. (Arithmetic) – this is the average current value over time. ⚡ The difference: When charging, the current is not perfectly constant – it is pulsating, because it comes from rectified #AC after #diodes. • The Arithmetic scale shows the average charging current. • The Effective scale shows the #RMS current, which is closer to the real “useful” current that stresses the charger and affects heating. That’s why the meter has two different scales – so you can read both the average and the RMS #current. 🔹 Difference between Arith and Eff When current flows through a #rectifier, it is pulsating. • Arith (average current) = just the average value of these pulses. • Eff (effective current) = the RMS value. It is always higher than the average, because it accounts for the peaks. Example (rectified sine wave): • If the meter shows 10 A Arith, then Eff will be about 11–12 A. • If the meter shows 20 A Arith, then Eff will be about 22–24 A. (The exact ratio depends on the charger design and the waveform, but usually Eff ≈ 1.1–1.2 × Arith). 🔹 What matters when charging #batteries For the battery itself, the average charging current (Arith) is what matters, because it determines how many ampere-hours actually go into the battery. • Arith → use this as the reference for charging current (for example, 10% of battery #capacity: a 200 Ah battery should be charged at about 20 A Arith). • Eff → useful to know for understanding the real load on the charger and heat generation, but less important for the user. • For the #battery → focus on Arith (average current). • For the #charger load → Eff (RMS current) is more relevant.

Formula and Table for calculating mA for each bar (0–15 bar, step 1 bar) for a pressure transmitter: 0–15 bar = 4–20 mA 24VDC Step: 1 bar • I – current (mA) • P – actual pressure • Pmin – lower range limit • Pmax – upper range limit The exact values depend on the range set for the transmitter. For example: • For 0–10 bar → 4–20 mA, the step will be 1.6 mA per 1 bar. • For 0–15 bar → 4–20 mA, the step will be 1.067 mA per 1 bar. • For 0–25 bar → 4–20 mA, the step will be 0.64 mA per 1 bar. #transmitter #pressure

Calibration of a Pressure Transmitter Using a Pressure Calibrator Pressure transmitters are widely used on ships and in industrial applications for monitoring and controlling process parameters. Most #transmitters provide a standard output signal of 4–20 mA, corresponding to the pressure range indicated on the nameplate. Over time, due to component aging and environmental factors, the transmitter readings may drift. To maintain #accuracy, #calibration is performed using a reference pressure calibrator and a multimeter to monitor the output signal. Initial Data In this example, the transmitter is Nagano Keiki KH55, with a measuring range of 0–1.5 MPa (0–15 bar). Output signal: 4–20 mA DC. Power supply: 24 VDC. Connection Setup 1. Power is supplied from a 24 VDC source. 2. A #multimeter in current measurement mode is connected in series with the loop (+). 3. The transmitter’s pressure port is connected to a pressure #calibrator (hand pump with a reference gauge). #Calibration Procedure 1. Zero Adjustment • At atmospheric pressure (0 bar), the transmitter output was 3.68 mA instead of the required 4.00 mA. • Using the #ZERO adjustment screw on the transmitter body, the value was corrected to 4.00 mA. 2. Span Adjustment • Pressure was increased to 15 bar (upper range limit). • The transmitter output was 19.71 mA instead of the required 20.00 mA. • Using the SPAN adjustment screw, the signal was corrected to 20.00 mA. 3. Intermediate Check • After Zero and Span adjustments, it is recommended to check several intermediate points (e.g., 5 bar and 10 bar). • The output should follow a linear relationship with the #pressure range: • 0 bar → 4.00 mA • 5 bar → 9.33 mA • 10 bar → 14.67 mA • 15 bar → 20.00 mA After adjustments, the transmitter provides a correct 4–20 mA signal corresponding to the 0–15 bar range. Calibration using the Zero and #Span method eliminates both zero offset and span error, ensuring linear accuracy across the measuring range.

🪛 Why I Never Use a Test Screwdriver on a Ship Again Once, I tried to check a live contact with a #test #screwdriver. At the same time, my other hand accidentally touched the switchboard’s metal frame. In that moment, I got an electric #shock. Why did it happen? A test screwdriver only works when #current flows through your body. On shore, it might feel like nothing, but on a #ship all switchboards and metal parts are bonded to the hull. By touching the panel, I closed the #circuit: phase → screwdriver → my body → ship’s hull. The current passed straight through me. Since then, no more “neon screwdrivers” onboard. Only proper #tools — a #multimeter or a #voltage #tester with insulated probes. ⚡ Safety first at sea. #safety #SafetyFirst

The #differential in a #pressure switch or #thermostat is the difference between the cut-in point and the cut-out point. It prevents the device from switching too frequently when #pressure or #temperature fluctuates around the setpoint. Example with a pressure #switch: • Setpoint: 6 bar (compressor starts). • Differential: 1 bar. • The compressor will stop at 7 bar and will restart only when the pressure drops back to 6 bar. Example with a thermostat: • Setpoint: +5 °C (compressor starts in a cold room). • Differential: 2 °C. • The compressor will stop at +3 °C and will start again at +5 °C. Why it is needed: • Reduces the number of on/off cycles. • Extends the lifetime of the equipment. • Prevents “chattering” around the setpoint.

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The output of a #thermocouple is always a voltage in millivolts (mV), generated due to the #temperature difference between the “hot” junction (measuring point) and the “cold” junction (connection point to the measuring device). • This voltage is called the thermo-EMF (thermoelectromotive force). • Its value depends on the thermocouple type (metal alloys) and the temperature. • Typical range: from tens of microvolts per °C up to a few tens of millivolts at high temperatures. • Example: • Type K at 100 °C → ~4.1 mV • At 1000 °C → ~41 mV So, a thermocouple does not output current and does not need external power – it works like a small #generator, producing a #voltage proportional to temperature.

A pressure calibrator is a measuring device used to generate, measure, and verify pressure, as well as to calibrate #sensors, transmitters, and pressure gauges. 📌 Main functions: 1. #Pressure generation – built-in hand pump or electric pump creates pressure or vacuum. 2. Pressure measurement – it has a high-accuracy reference sensor to show the actual pressure. 3. #Calibration – compares the readings of the device under test (gauge, #sensor, or transmitter) with the reference value. 4. Multifunction capability – often provides 24 VDC power supply and can measure 4–20 mA or mV signals from pressure transmitters. 📌 Applications: • On vessels, to test #pressure, level, and flow transmitters (typically working with 4–20 mA signals). • In industry, for maintenance of pressure #transmitters, #gauges, and #switches. • In laboratories and metrology, for verification and calibration of reference instruments. Pressure #calibrator is a reference source and measurement tool for pressure, ensuring that working instruments give accurate readings.

A turbidity sensor in a #WTS #EGR (Water Treatment System for Exhaust Gas Recirculation) is a sensor that measures the cloudiness (suspended solids) in the wash water. Function: • Monitors the amount of suspended particles in the discharge water from the EGR system. • Works on an optical principle (light scattering or absorption). • Ensures compliance with #IMO requirements MEPC.307(73) and #MEPC.259(68). Purpose: • International regulations limit the amount of suspended solids allowed in wash water discharged overboard. • The turbidity sensor sends a signal to the automation system. If the turbidity exceeds the limit (typically around 25 FNU/NTU), the system triggers an alarm or switches the wash water to recirculation mode. Typical wash water monitoring sensors in WTS: 1. #pH sensor – monitors acidity/alkalinity. 2. #PAH sensor (Polycyclic Aromatic Hydrocarbons) – monitors hydrocarbons. 3. #Turbidity #sensor – monitors suspended solids.

Each #thermocouple is made of different alloys, and its thermoelectric #EMF (mV/°C) is unique. Here are some examples for comparison (reference junction at 0 °C): • Type K (Chromel–Alumel): • 100 °C → ~4.1 mV • 500 °C → ~20.6 mV • 1000 °C → ~41.3 mV • Type J (Iron–Constantan): • 100 °C → ~5.3 mV • 500 °C → ~26.4 mV • 1000 °C → ~55.0 mV • Type T (Copper–Constantan): • 100 °C → ~4.3 mV • 300 °C → ~12.1 mV (maximum operating temperature is only about 370 °C, so it is rarely used above this) • Type N (Nicrosil–Nisil): • 100 °C → ~3.8 mV • 500 °C → ~19.0 mV • 1000 °C → ~38.0 mV • Type S (Platinum–Rhodium 10% / Platinum): • 100 °C → ~0.65 mV • 500 °C → ~4.7 mV • 1000 °C → ~10.2 mV • Type R (Platinum–Rhodium 13% / Platinum): • 100 °C → ~0.65 mV • 500 °C → ~4.7 mV • 1000 °C → ~11.0 mV 📌 As you can see: • For the base-metal thermocouples (K, J, T, N), the output #voltage is higher and increases faster with #temperature. • For the platinum-based thermocouples (S, R, B), the EMF at the same temperatures is much lower (about 4–5 times less), but they are more stable at high temperatures (up to 1600 °C).

Type K #thermocouple reference table (#temperature vs. output #voltage at 0 °C reference). • At 0 °C → 0.000 mV • At 100 °C → 4.096 mV • At 200 °C → 8.138 mV • At 300 °C → 12.209 mV • At 400 °C → 16.397 mV • At 500 °C → 20.644 mV • At 600 °C → 24.905 mV • At 700 °C → 29.129 mV • At 800 °C → 33.275 mV • At 900 °C → 37.326 mV • At 1000 °C → 41.276 mV • At 1100 °C → 45.119 mV • At 1200 °C → 48.838 mV

For #Pt100 (according to #IEC 60751, α = 0.00385), the resistance increases almost linearly with temperature, with a slight deviation at higher values. Here are the values: • 100 °C → 138.51 Ω • 200 °C → 175.86 Ω • 300 °C → 212.05 Ω • 400 °C → 247.09 Ω • 500 °C → 280.98 Ω • 600 °C → 313.71 Ω • 650 °C → 329.70 Ω ⚠️ Something went wrong with the 650 °C value 🤦‍♂️ #temperature #sensors

Difference between Pt100 and Pt1000 sensors 1. Nominal #resistance • Pt100 → 100 Ω at 0 °C • Pt1000 → 1000 Ω at 0 °C Both follow #IEC 60751 (α = 0.00385). 2. Sensitivity (resistance change per 1 °C) • Pt100 → ~0.385 Ω/°C • Pt1000 → ~3.85 Ω/°C (10 times higher) ➡ Pt1000 provides a larger signal change, which makes it less sensitive to noise. 3. Influence of lead wire resistance • With Pt100, wire resistance introduces noticeable error, especially in 2-wire connection. • With Pt1000, the same wire resistance has 10× less relative effect. ➡ That’s why Pt1000 can often be used with simple 2-wire circuits, while Pt100 is usually used with 3- or 4-wire connections. 4. Application range • Pt100 → widely used in industrial applications, reliable at high temperatures. • Pt1000 → common in HVAC, household, and automotive systems, where simple wiring and good accuracy at moderate temperatures (~200–250 °C) are enough. 5. Cost and availability • Pt100 is the industry standard. • Pt1000 is cheaper and more common in mass-market devices. • #Pt100 = industrial standard, stable, wide #temperature range. • #Pt1000 = higher sensitivity, less cable influence, good for simple 2-wire circuits.

Minor maintenance #DavitWinch #winch #motors #motor

Reference #resistance tables for #Pt100 (IEC 60751, α = 0.00385) from 0 to 650 °C and from –200 to 0 °C in 50 °C steps. The #tables are universal and the same for all classes (A, B, 1/3B, 1/10B, etc.) because they show the ideal resistance values at a given #temperature.

Main Types of #Thermocouples (IEC/ANSI Classification) • Type K (Chromel – Alumel) Range: approx. –200…+1200 °C The most common, universal, inexpensive. Used in industry, furnaces, boilers. • Type J (Iron – Constantan) Range: –40…+750 °C Sensitive but less stable at high temperatures. Found in older equipment and laboratories. • Type T (Copper – Constantan) Range: –200…+350 °C Very accurate at low temperatures. Used in cryogenic systems, refrigeration. • Type E (Chromel – Constantan) Range: –200…+900 °C High sensitivity (large mV/°C signal). Good for low-temperature applications. • Type N (Nicrosil – Nisil) Range: –200…+1300 °C More resistant to oxidation than Type K. Used in power plants and metallurgy. • Noble metal thermocouples: • Type S (Platinum–Rhodium 10% / Platinum) Up to +1600 °C, used as a reference in labs. • Type R (Platinum–Rhodium 13% / Platinum) Similar to S, slightly higher sensitivity. • Type B (Platinum–Rhodium 30% / Platinum–Rhodium 6%) Up to +1800 °C, not sensitive at low T. Used in glass and metal industries. By Construction: • Insulated (in sheath, ceramic beads, mineral insulated). • Non-insulated (exposed junction for fast response). • Single or multi-junction (multiple measurement points in one sheath). • Immersion, surface, contact, gas analysis types. #thermocouple

An adapter sleeve in a #temperature calibrator is a removable metal insert (with one or multiple holes) that is placed inside the metal block of the #calibrator. Purpose: • Ensures proper thermal contact between the temperature sensor (test specimen, e.g. #Pt100 or #thermocouple) and the heated block. • Reduces air gaps, which improves the accuracy of temperature transfer. • Allows the calibrator to be used with sensors of different diameters simply by changing the sleeve. Material: According to the manual: “Only use the supplied adapter sleeves made of the appropriate material. If in doubt, contact #SIKA for clarification.” This means the sleeves are made of a special material provided by the manufacturer—typically a highly conductive metal such as aluminum, #brass, or sometimes stainless #steel. The material is selected to: • withstand a wide temperature range, • have good thermal conductivity, • resist oxidation and avoid getting stuck in the block. An adapter sleeve is a replaceable metallic insert with holes for temperature #sensors, usually made of #aluminum or a similar thermally conductive material supplied by the manufacturer.

The table, showing the nominal #resistance of #Pt100 at each #temperature and the Class B tolerance in Ohms.

Types of Pt100 Sensors #Pt100 is a platinum resistance temperature detector (#RTD) with a resistance of 100 Ω at 0 °C. Different types and designs of Pt100 sensors exist, classified as follows: 🔹 1. By sensing element construction • Wire-wound – platinum wire wound on a ceramic or glass core. ➝ More accurate and stable, but sensitive to vibration. • Thin-film – thin #platinum layer deposited on a ceramic substrate. ➝ Compact, cheaper, vibration-resistant, but less durable at very high #temperatures. 🔹 2. By #temperature range • Standard: –50…+250 °C (thin-film). • Extended: –200…+600 °C (wire-wound). • High-temperature: up to +850 °C (special designs). 🔹 3. By accuracy class (#IEC 60751) • Class AA – highest accuracy (±(0.1 + 0.0017·t) °C). • Class A – high accuracy (±(0.15 + 0.002·t) °C). • Class B – standard accuracy (±(0.3 + 0.005·t) °C). • Class C – low accuracy, rarely used. 🔹 4. By #wiring configuration • 2-wire – simplest, but least accurate due to cable resistance. • 3-wire – most common, compensates for lead wire resistance. • 4-wire – for precision measurements, eliminates cable influence. 🔹 5. By mechanical design • With protective sheath (stainless steel, Inconel, etc.). • Bare element (miniature, for integration into devices). • Cable type (flexible, with heat-resistant insulation). • Connector type (standard industrial DIN connector). • Immersion sensors (for liquids, gases). • Surface-mount sensors (for pipes or flat surfaces).