HCOTEG174270 - Flow meters - other information: What can make flow meters inaccurate?

The type of flow meter used is a function not just of the accuracy of the meter itself,but also of its suitability to cope in the conditions in which it is used.

The factors that affect meters are:

  • Turbulence caused by bends in pipe work before the meter 바카라 사이트“ this can affect all types of meter 바카라 사이트“ indeed, some types of meter work by measuring turbulence caused by a fixed obstruction 바카라 사이트“ so that any additional turbulence will make the meter inaccurate.
  • Bubbles 바카라 사이트“ anything that allows air or gas into the pipe could again cause most meters to be inaccurate, by changing the volume.
  • Viscosity of the fluid 바카라 사이트“ may be illustrated by the difference in viscosities between lubricating oil and white spirit. Thicker lubricating oil has to be heated to thin it and then pumped and stored in heated or insulated pipes and tanks. Thinner white spirit has 2 adverse effects: it has no lubricating properties to protect the meter through which it is flowing, and its 바카라 사이트˜thinness바카라 사이트™ means that the meter has to maintain a very tight seal where there are moving parts 바카라 사이트“ accordingly they tend to wear out quickly.
  • Temperature 바카라 사이트“ the density of the oil reduces the hotter it becomes 바카라 사이트“ plus some flow meters work by measuring temperature variation.
  • Vibration 바카라 사이트“ 바카라 사이트˜Coriolis바카라 사이트™ meters in particular are affected by vibration because they use vibration in order to produce a measurement, so mounting them on a vibrating jetty as has happened, will render the meter inaccurate.
  • Small amounts 바카라 사이트“ a meter should be able to measure less than 2 litres for revenue accounting but some find it difficult to measure flows that stop and start 바카라 사이트“ (also see 바카라 사이트˜linearity)
  • Changing flow rates 바카라 사이트“ flow meters used for loading have to be accurate from a standing start, and initially the loading of tankers is at a low flow rate. If the loading were done at a high flow rate, the fuel sloshing round an empty tank could generate enough static electricity to cause a spark. After sufficient fuel is in the tank, the flow rate is turned up to finish the load as quickly as is practical and safe.
  • Electromagnetic interference 바카라 사이트“ (possibly generated by electrical equipment, transformers, microwave aerials such as mobile phone masts) can affect meters that work by measuring magnetic interference and might affect computers and transmission equipment built into the meter. They could cause extra current to be induced into a wire or flaws/pulses to be generated. They may also interfere with microwave transmission, where meter readings are wireless, and are transmitted instead to a control room.
  • Non oil products 바카라 사이트“ Meter systems should include suitable filters upstream so that any particles or solids do not enter the meter and cause interference with the measurement device.