EHS-61 and EHS-62 Electric Heating Systems

EHS-61 and EHS-62 Electric Heating Systems

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The HEATPAC Electric Heating Systems are specifically designed for the heating of mineral oils in booster systems and prior to centrifugal cleaning.

The HEATPAC Systems are type-approved by ABS, BV, DnV, GL, LR, NK, RINA, RMRS.


The HEATPAC EHS System (Fig. 2) comprises:

  • Heater EHM.
  • HEATPAC control unit (EHS-61 only).
  • HEATPAC power unit (EHS-62 only).
  • Ancillary equipment including PT-100 temperature sensor, high temperature sensor and safety valve.


The unique features of the HEATPAC System are:

  • Compact and lightweight design.
  • Incremental electronic temperature control.
  • Specially designed heating elements for high-efficiency heat transfer.
  • Fully automatic operation.


The main benefits include:

  • Ease of installation.
  • Instant temperature control. Temperature accuracy to within ±1°C.
  • Gentle treatment. No deterioration of heated oil.
  • Start-and-forget operation.
  • Optimum heating of all types of mineral oils, particularly high-density, high-viscosity fuel oils, sensitive lubricating oils and turbine oils.

Fig. 2. Basic concept of the HEATPAC EHS System.

System working principle

The fuel or lubricating oil is fed continuously to the HEATPAC heater. A signal from the Pt-100 temperature sensor at the oil outlet is transmitted to the HEATPAC control unit (EHS-61) or external controller, such as an EPC-41/400 or EPC 50 (EHS-62) which regulates the amount of electric power to the heating elements. Heat is transferred to the oil through the corrugated aluminium surface. (Fig. 3).

Overall incremental operation is automatically controlled by the HEATPAC control unit or the external controller. The HEATPAC control unit and power unit features specially designed thyristor modules which perform the incremental feeding of power and prevent any interference with other shipboard electric and electronic equipment. A unique characteristic of the cast aluminium heating elements is the rapid response to any load change. This feature, in combination with the specially designed control system, ensures outstanding control performance, independent from any fluctuations in flow rate or oil temperature.

Standard safety equipment comprises a high temperature sensor located in close proximity to the aluminium heating element. (The high temperature sensor cooperates with an independent temperature guard in the control unit / power unit to ensure protection from overheating.) Further the heater automatically turns off if the pump starter is turned off. This feature ensures that the heater is fully protected from overheating in the event of a systems operations failure.


Fig. 3. Working principle of the HEATPAC System.

Heater capacity

The actual capacity depends on temperature increase and flow rate. Six sizes are available, from 7 to 72 kW. The power loads for each size are shown in Fig. 4.


Fig. 4. Size chart and power loads based on temperature and flow rate (not for dimensioning).

Main system components

HEATPAC EHM Heater, standard design

The heater comprises rectangular diecast aluminium heating elements mounted on a flange to form a compact heating block which is inserted in a pressure vessel made of mild steel. A baffle inside the vessel divides the flow into two passes. The oil inlet and outlet are located opposite each other on the same level, enabling installation in a series.

The terminal box housing at the top of the heater is separated from the hot pressure vessel to maintain a low temperature in the box. The hot side of the pressure vessel is adequately insulated with 25-mm mineral wool wrapped in aluminium sheet.

Technical data

Design pressure:1.5 MPa (15 bar)
Test pressure:2.25 MPa (22 bar)
Max. temperature:160°C
Power supply:230, 400, 440, 480, 690 VAC, 50/60 Hz

HEATPAC control unit (EHS-61 systems), standard design

The control unit, housed in a robust cabinet, comprises a control module, two thyristor modules and contactors for feeding electric power to the heater. The control module containes the essential plant-dependent parameters and a PI regulating function.

The front panel is equipped with power switch and modeselection switch, alarm lamp push button, three push buttons for setting of parameters, and a sectional display window indicating current temperature. Six light-emitting diodes behind the display window clearly indicate mode of operation and alarm signals. Values and codes for alarm identification are shown on the panel. The control unit can be linked to a remote computer in the control room through a current-loop interface.

Technical data

EPC 50
Operating voltage:24 VAC
Power supply:400, 440, 480, 690 VAC
50/60 Hz
Dimensions:_24 kW: H/540, W/550, D/260
36-72 kW: H/730, W/550, D/320
Max. ambient temperature:55°C
Protection class:IP65
Weight:40 kg
EPC 41/400
Operating voltage:48 VAC
Power supply:230, 400, 440, 480 VAC
50/60 Hz
Dimensions:_24 kW: H/540, W/550, D/260
36-72 kW: H/730, W/550, D/320
Max. ambient temperature:55°C
Protection class:IP65
Weight:40 kg

Fig. 5. HEATPAC EHM Heater.

HEATPAC power unit (EHS-62 systems)

The power unit, housed in a robust cabinet, comprises two thyristor modules, contactors and overcurrent protection for feeding electric power to the heater.

For operation it depends on an external controller, i.e., the separation systems EPC.

There are two cabinet sizes, one up to 24 kW and the other for 36