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2800i High Accuracy Servo Tank Gauge

Motherwell Control Systems 2800i High Accuracy Servo Tank Gauge is designed specifically for use in Custody Transfer and Inventory Management applications across the full range of modern storage tank designs.

2800i measures product level, water interface and product density in a single micro-processor based unit.

Connecting the gauge to one of the Motherwell Control Systems range of MCS 3780 Series temperature probes provides measurement of both product and vapour temperature.

2800i Level Measurement

  • Dynamic product level measurement – accurate to ±1mm.
  • Self referencing – the gauge can be commanded to self check by returning to the tank top reference point.
  • Bottom referencing – measures sediment accumulation and/or tank base.
  • Turbulence filtering eliminates the effect of ripples to give continuous true level measurement.
  • Tank deformation compensation.
  • Up to four level alarm contacts.

2800i Temperature Measurement

  • Temperature measurement – accurate to ±0.1 ºC
  • Accepts Single Spot, Multiple Spot or averaging Temperature Probes
  • All elements of Multiple and Averaging Probes are read continuously.
  • Temperature profiling illustrates thermal product stratification and provides vapour temperature measurement.

2800i Interface and Density Measurement

  • Water Interface measurement – accurate to ±2mm.
  • Density profile measurement
  • Density profiling illustrates product stratification

2800i Principle of Operation:

Motherwell Control Systems 2800i measures liquid level based on the principle of liquid displacement. A displacer is suspended on a stainless steel wire payed out from a grooved drum housed in the gauge enclosure.

A highly sensitive torque measurement device continuously measures the effective weight of the displacer which, under steady state level conditions, is half immersed in the liquid. Should the level change, the displacer undergoes an apparent change of weight. The gauge microprocessor senses this change in weight and causes a servo motor to rotate the measuring drum until balance is restored.

Density is determined by measuring the effective weight of the displacer when completely immersed. Sample readings, recorded at configurable intervals as the displacer travels down through the liquid, provide density profiling.

Water Interface level and tank base measurement are achieved by recording the point at which the gauge recognises the effective displacer weight in water and at the tank base respectively.


Key Benefits of Motherwell Control Systems 2800i Servo Gauge :

  • Intrinsically Safe (Eex ia IIB T4) with the added benefit of no electronics exposed to the tank atmosphere.

  • Low power requirements enable both power and communications to be safely distributed via one 4-wire cable running around the tank farm.

  • High Visibility large Liquid Crystal Display provides selectable Level, Temperature, Interface or Density readings at all times.

  • Optional display for mounting at tank base.

  • Non-volatile memory: 2800I will restore itself to full operation in the event of a power loss.

  • Operates across a wide range of process and environmental conditions.

  • Range of installation options to suit all tanks, including high pressure applications; and a flexible coupling installation for tanks with undefined deformation characteristics.

  • Local control by single push-button: user friendly.

  • Remote control and monitoring via industry standard multi-dropped serial communications, including extensive diagnostic information.

  • Lightning Protection through galvanic isolation.

  • Excellent track record – proven in a wide variety of applications.

  • Low maintenance.

Why Intrinsically Safe?

Many people have asked the question WHY is 2800I certified Intrinsically Safe when all other Tank Gauge manufacturers have chosen Explosion Proof protection.

The answer is quite simple. Whilst Intrinsic Safety requires specialist skills in design, there are tremendous benefits to be gained in terms of operation and maintenance.

Intrinsic Safety (IS) Means:

High operational safety –
‘PREVENTION RATHER THAN CURE TECHNOLOGY’ means that the gauge is safe in all circumstances, even when the integrity of the electronic enclosure is compromised.

High reliability – the electronic components are operating at extremely low current levels and consequently 2800I is considerably less prone to component failure than non-IS circuitry.

Other Points for Consideration

2800I electronics are certified for use in Zone O (inside the tank). 2800I electronics are not however, exposed to the tank atmosphere – the drum enclosure is magnetically coupled to the enclosure containing the motor and electronics.

The 2800I therefore far exceeds the requirements of hazardous area approvals.

Current consumption

2800I is certified Ex ia IIB T4.

People occasionally ask how 2800I has been certified IS when the current quoted on the gauge display label reads what might, in instrument terms, be considered a high figure at 276mA.

The answer lies in the criteria utilised for approval. The test report from the UK Health & Safety Executive, BASEEFA, discusses the input / output parameters of each section of the gauge. As you can see, the current is only one parameter considered when granting IS certification – the voltage, power, current and particularly the capacitance and inductance of the unit are all used together in assessing the IS rating – which revolves around energy storage. 2800I has extremely low capacitance and inductance and is simply incapable of causing ignition in the IIB T4 environment.

Maintenance and Service

Simple maintenance – 2800I can be maintained in service. IS certification means that the electronics can be worked upon to allow verification and fault finding whilst installed on the tank. Eliminating the costly and time-consuming task of removing the gauge, to a safe working area for service and testing. A tremendous advantage over explosion proof equipment where the fault conditions may ‘disappear’ in the workshop environment.

These advantages of the MCS Servo Gauge as you will appreciate can give a significant reduction to the gauge “Out of commission” time, during the period of service. It will also reduce the required level of servicing manpower. Since the removal and transportation of the gauge from the storage tank is no longer a requirement, the task can now be easily accomplished by one Service Engineer.

Then, in addition to operational safety offered by the MCS Servo Gauge, the risk of danger to servicing personnel is reduced by it’s “Intrinsic safety,” permitting improved and much safer working practices at the tank top. In fact the intrinsic safety of the gauge not only diminishes potential risk of damage to personnel but also the equipment.

With an MCS 2800i Servo Tank Level Gauge, installation to the storage tank is a one off event at the time of initial installation and commissioning. Further, with its proven track record of service and reliability, it is by far the best solution to our client’s level gauging requirements.