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HS Sensors

Marine: machine vibration monitoring

At sea, access to spare parts and service is limited, and a failure of a pump, generator set or gearbox directly affects the safety and operation of the ship. Vibration monitoring helps to plan maintenance work on board and on quayside equipment based on the actual condition of the machines.

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Marine
Photo: William William / Unsplash

What fails most often

The engine room crew has a limited stock of parts and tools, and major repairs have to be planned for a stay in port or at a shipyard. Early detection of a cooling pump bearing fault, generator set misalignment or gearbox wear gives time to order parts and prepare the repair, instead of working in emergency mode at sea.

Sensor operating environment

Salt-laden air, high humidity and condensation promote corrosion of housings and connectors, and the engine room adds oil mist and high temperatures near the engines and turbochargers. The hull transmits vibration from the main engine and the propeller; this vibration appears in the spectra of auxiliary machines and must be taken into account in the analysis. Electrical installations on ships often operate as insulated networks, so it is important that the sensor’s measurement loop does not form a connection to the hull.

On tankers and gas carriers, some equipment — including cargo pumps — operates in hazardous areas. Quayside equipment, in turn, is exposed to rain, salt mist and large temperature variations.

Typical machines

Ballast, cooling and bilge pumps
unbalance, cavitation, mechanical looseness
Engine room and HVAC fans
bearing damage, misalignment
Reduction and drive gearboxes
gear tooth damage, bearing wear
Generator sets and generators
misalignment, unbalance, bearing damage
Propulsion systems: engines, couplings and shaft lines
misalignment, premature wear of components
Turbochargers
rotor unbalance and changes in bearing condition at high temperature
Cargo pumps on tankers and gas carriers
bearing damage, cavitation, unbalance

From the machine to the monitoring system

  1. 01Machines in this industry

    Ballast, cooling and bilge pumps, engine room and HVAC fans, reduction and drive gearboxes and others — measuring point on the bearing housing.

  2. HS-104R — Low-power triaxial accelerometer, top exit, PUR cable

    02Sensor

    An IEPE accelerometer or a 4–20 mA sensor converts vibration (and often temperature) into an electrical signal.

    Industrial IEPE accelerometers
  3. HS-AA018 — Inline adaptor

    03Signal

    A cable with the right connector and a junction box carry the signal from many measuring points to the system.

    Cables and connectors
  4. HS-570-60 — Power supply module

    04Monitoring

    PLC, DCS, an online system or a data collector: trends, alarm thresholds and diagnostics before a failure happens.

    Vibration systems and switches

How to choose the measurement

Measurements from hard-to-reach places

The HS-100 accelerometers with a 100 mV/g output are permanently mounted at the bearings of machines hidden under engine room floor plates or in tight compartments, and their cables are run to an HS-SE switch box. Measurements are then taken with a standard data collector from one accessible place, always at the same points.

Integration with the ship’s alarm system

The HS-420 sensor provides a 4–20 mA signal proportional to vibration velocity, which can be fed to the onboard PLC or the alarm and monitoring system. This way, the crew on watch can see the vibration trend of selected machines together with other operating parameters — see 4–20 mA vibration sensors.

Turbochargers and hot spots

The HS-105 is intended for turbochargers and other high-temperature locations. It is an accelerometer that operates at up to 250 °C with an external charge amplifier. The signal can be routed to a local connection box or via a multi-core cable to the higher-level system. You will find the versions in the high-temperature accelerometers category.

Hazardous areas

Intrinsically safe HS-100I accelerometers with ATEX and IECEx certificates are intended for cargo pumps on tankers and gas carriers — see accelerometers for Ex zones. The manufacturer designs its marine sensors for operation in unearthed circuits; even so, when selecting a sensor, check the datasheet for the isolation of the signal circuit from the housing and the parameters required for the barrier.

Enclosures and cables

HS-JE junction boxes and HS-SE switch boxes are available in stainless steel, painted steel and polycarbonate enclosures; on deck and in places exposed to salt mist, stainless steel works best. Halogen-free cables are often required in the ship’s enclosed spaces — the catalogue includes sensor versions with HFFR cable.

Recommended versions

All products for this industry (44)

Product groups for marine

Industry questions

Does hull vibration interfere with measurements on auxiliary machinery?

Vibration from the main engine and the propeller is transmitted through the structure and appears in the spectrum as components at their characteristic frequencies. Spectrum analysis makes it possible to separate them from the symptoms of faults in the machine itself. It is important to compare measurements taken under similar operating conditions, e.g. at a similar main engine load.

Which cable should I choose for sensors in the engine room?

The choice depends on the location. Near engines, resistance to oils and temperature matters; on routes exposed to damage, a braid or protective conduit; and in enclosed spaces, a halogen-free cable is often required. The permissible temperature and chemical resistance vary with the cable type, so check them in the datasheet of the selected version.

Is an intrinsically safe sensor alone enough on a tanker?

No. The entire measurement chain must be intrinsically safe: the sensor, the cable, and the barrier or isolator located outside the hazardous area. Their parameters must be compatible with each other. The HS-100I has ATEX and IECEx certificates, but before installation, check that its marking matches the zone and gas group at the location. The classification society may impose additional requirements.

Sensors for a ship or quayside

Send us a list of equipment, a description of the conditions at the mounting location and the requirements of the shipowner or classification society. We will help you select sensors, cables and enclosures.

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