Monitoring the health of large marine propulsion engines is critical for ensuring operational safety, efficiency, and longevity. Two key indicators of engine condition are the internal crankcase pressure and the temperature of the lubricating oil. An engineering firm specializing in marine propulsion systems required a single, robust instrument capable of measuring both of these parameters simultaneously within the harsh environment of an engine room. The solution needed to be sensitive enough to detect very small changes in pressure while being durable enough to withstand constant vibration and exposure to hot oil.
- Application: Marine engine crankcase monitoring
- Parameters: Low-range gauge pressure and splash oil temperature
- Challenge: Combining two measurements into one instrument for a harsh, high-vibration environment
- Solution: ATM/T dual pressure and temperature transmitter
A customer involved with the automation systems for marine propulsion units was tasked with finding a reliable method for monitoring the crankcase conditions of large diesel engines. The primary requirements were to measure both the crankcase pressure, which is a critical indicator of piston ring “blow-by,” and the temperature of the splash oil, which reflects the health of the lubrication system. A significant challenge was the low operating pressure, specified as a gauge range of 0 to 500 mbar. An increase in this pressure can signal excessive wear and potential engine damage, making accurate and sensitive measurement essential.
The environment itself presented further challenges. The sensor would be mounted directly onto the engine crankcase, exposing it to significant vibration, high ambient temperatures, and direct contact with lubricating oil. Furthermore, to simplify installation and reduce the number of potential failure points, the customer strongly preferred a single instrument that could provide separate, independent outputs for both pressure and temperature to their automation system. This dual-measurement capability in one compact device would save space and reduce wiring complexity in an already crowded engine room.
The proposed solution was the ATM/T series dual output transmitter. This multiparameter probe is specifically designed to address such applications by integrating both a piezoresistive pressure sensing element and a Pt100 temperature sensor into a single, compact assembly. Its modular design allows for customization to meet the precise needs of the application, including the customer’s required low-pressure range of 0-500 mbar gauge. The sensor’s high-sensitivity electronics and excellent thermal stability ensure accurate pressure readings despite the temperature fluctuations inside the crankcase.
To withstand the demanding marine environment, the ATM/T features a robust housing and process connection machined from 316L stainless steel, offering high resistance to corrosion and mechanical stress. The wetted parts, including the frontal diaphragm and standard Viton seals, provide excellent compatibility with engine oils. The frontal diaphragm design is particularly advantageous as it sits flush with the process connection, minimizing the risk of clogging from oil contaminants. For signal reliability in an electrically noisy engine room, the transmitter complies with EMC directive 89/336/EEC for immunity to electrostatic discharge and radiated radio frequencies from nearby equipment. The specified DIN 43650 electrical connector is a proven, rugged industrial interface that provides a secure, vibration-resistant connection, ensuring uninterrupted data transmission to the ship’s control system.
ATM/T Pressure and Temperature Dual Output Transmitter
- Pressure Range: 0 – 500mbar G
- Output Signal: 4-20mA / 2-wire (shared GND with temperature sensor)
- Temperature Range: 0 to 100°C
- Output: 4-20mA / 2-wire (shared GND with pressure sensor)
- Accuracy: <±0.5% FS
- Electrical Connection: DIN 43650 with metal threaded part, demountable
- Process Connection: G 1/2 male, frontal diaphragm
- Seals: Viton (standard)