Danfoss 061B800266 MBC 8100 Thermostat 20-60 C

MBC 8100: a compact marine thermostat with fixed 3 K differential

Danfoss 061B800266 is an MBC 8100 thermostat. It belongs to the same block-design family as the MBC pressure switches and is made for severe industrial and marine conditions where space and reliability matter most. The data sheet states that the MBC 8100 carries all international marine approvals and that both MBC 8000 and MBC 8100 resist vibration strongly. The rigid 13 x 50 mm sensor sits in a pocket and the switch covers 20 to 60 C with a fixed differential of 3 K.

The fixed differential removes one adjustment and one source of error: the contact always returns 3 K after it trips, which suits alarm duty such as high jacket-water temperature or high bearing temperature.

Technical specifications

Alarm and monitoring uses

In an engine room the MBC 8100 monitors cooling-water outlet, lube-oil cooler outlet, gearbox temperature and hydraulic oil. Its housing is IP65, it connects through a DIN plug and the maximum sensor temperature is 130 C, so a fault that heats the sensor far above the 60 C limit will not destroy the element. Mounting is directly in the M 18 x 1.5 pocket connection, which saves cable and capillary runs.

The standard version offers an SPDT contact with a 0.5 A, 250 V AC15 rating, so signals are normally taken to a PLC or alarm relay rather than to a motor.

Installation and ordering notes

Use a pocket of at least 75 mm, fill it with heat-conductive paste and tighten the pocket in the process connection. Plug the DIN connector and check the contact operation with a temperature bath before commissioning.

The approvals printed for this code include DNV, GL, KRS, LR, NKK and RINA with CE and EAC; other MBC 8100 versions use capillary tubes, armoured capillaries or other ranges and have other code numbers. Seven Star LLC is an independent supplier in Muscat; send 061B800266 with the quantity for a quotation.

Projects that use 061B800266 often need related parts from the same manufacturer, such as connectors, mounting parts or spare kits. Mention them in the same enquiry so that compatibility can be checked together rather than discovered on site, when a missing part stops the work.

Before you order 061B800266, compare it with the nameplate of the unit you intend to replace. Photographs of the nameplate help us to confirm the exact code quickly, and we will tell you plainly if a different version of the same family looks like a better fit for your duty.

Choosing a set point for alarm duty

Because the MBC 8100 has a fixed differential, the main decision during selection is where inside the 20 to 60 C range the switching point should sit. Begin with the normal operating temperature of the medium and the temperature at which the plant operator wants to be warned. The set point must be far enough above normal operation that ordinary load changes do not cause nuisance alarms, yet low enough that the warning arrives while there is still time to act. Remember that the contact resets only after the temperature falls back by the differential, so a set point placed too close to normal operation can leave the alarm latched longer than expected.

• Confirm the alarm temperature lies inside the 20 to 60 C range of this code.
• Decide whether the alarm should open or close a circuit on rising temperature and wire the SPDT contact accordingly.
• Check that the receiving PLC input or alarm relay is within the contact rating listed above.
• Verify an M 18 x 1.5 pocket of suitable length exists or can be fitted at the measuring point.

Commissioning and periodic testing

A temperature switch used for alarms is often untouched for long periods, so testing matters more than for a control device that switches every day. During commissioning, record the actual switching temperature found in the bath test, the reset temperature and the tag number of the point. Mark the set point on the drawing and in the alarm list so later checks have a reference. On ships and in plants, include the thermostat in the planned maintenance routine: remove it from the pocket, repeat the bath test, inspect the DIN plug and cable entry for moisture and confirm that the alarm reaches the control room or monitoring panel.

Sensor contact with the pocket

The rigid sensor responds through the pocket wall, so response time depends on good thermal contact. Renew the heat-conductive paste whenever the sensor is withdrawn and make sure it is fully inserted before the housing is secured.

Gulf engine rooms and plant rooms

Engine rooms on vessels and generator halls in Oman and the GCC can be very hot, especially in summer, and are often humid near the coast. The thermostat’s ambient range covers these conditions, but the housing should still be placed where it is not directly exposed to radiant heat from exhaust parts or to washing spray. Keep the DIN plug properly seated and the cable entry sealed so the IP65 rating is maintained, and route cables away from hot surfaces. Where several MBC 8100 units serve one engine, label each housing clearly with its set point and function so that replacements are fitted to the correct point.

Documents and quotation

The attached Danfoss MBC 8000 / MBC 8100 thermostat data sheet AI556240522700 gives ranges and code numbers. Related items appear in temperature instrumentation. The data sheet code table also lists the pressure versions of the same block design, so a mixed order for an engine-room panel can be checked against one document before it is sent.