The industrial line includes instruments for the measurement and control of fluids, liquids or gaseous, to be used in the pipelines of the plants or on the machines.
The various types of flow indicators are divided into:
Flow switches, Electronic flow switches, Digital flow switches, Atex flow switches, Flow meters, Visual flow indicators.
Electronic flow switches are two-state devices (open or closed of a switch) used to detect a specific flow rate value of a fluid.
Unlike the flow meter, the flow switch is unable to perform any measurement. The device actually has an activation threshold value, normally spaced from the deactivation value by a suitable hysteresis, designed to limit the unwanted effects of switching around the threshold value. In order to carry out instantaneous flow measurements, a digital flow switch is used.
Unlike a flow meter, a flow switch does not perform measurements: in effect, the device has an activation threshold value that is usually distanced from the deactivation value by a suitable hysteresis, so as to limit the undesired effects of switching round the threshold value.A flow switch, is used in control systems where a planned level is useful or necessary to obtain a change of state for a specific flow value, for example, in heating systems where the temperature sensors are not positioned close to the heating element, it prevents the damage caused by a sudden cut off of circulation.The most common flow switch models are electromechanical , where the mechanical part immersed in the fluid acts as a switch by means of levers. These models have an intervention threshold that can be changed varying the length of the lever arm (paddle) or contrast spring. Depending on the applications, an Atex flow switch is also available and is ideal for places with an explosion hazard.Flow meters are instant flow gauges suitable for measuring low, medium and high flows of any type of fluid being piped (even corrosive or acidic), with temperature and pressure conditions contained within the resistance limits of the glass tube.In the flow meters, the measuring of the flow can be read with great precision on the graduated scale recorded directly on the measuring tube; upon a customer's request, the reference scale of a specific fluid can be produced.The connections can be threaded or flanged and the manufacturing materials carbon steel, AISI 316L, PVDF, PP (upon request: Hastelloy C, Monel, Titanium). Depending on the required executions, there are accessories available such as Plexiglas or polycarbonate protection for the measuring tube, a guided float, a minimum and maximum flow alarm signal (inductive Namur type, CENELEC approved, intrinsically safe EEx ib IIC T6), Reed alarm contact.
The range of flow meters includes the metal tube flow meters (more widely used than those with the glass tube) can measure opaque and chemically aggressive fluids, at high temperatures and high working pressures. These flow meters are fitted with a microprocessor for electrical transmission of the signal which has the Hart protocol and they have an 8-letter LCD display for the instantaneous, total and percentage flow.
They are also available for low pressures and when there are fluid hammers and in the certified versions ATEX, intrinsically safe EEx ia and explosion proof EEx d for applications in potentially explosive areas.
Visual flow indicators are instruments suitable for an instantaneous control of fluids in all industrial processes.
Produced with instantaneous flow indication for horizontal pipelines using either a floating paddle with a scale that can be read on a backlit graduated double disc in toughened glass, or, a pointer with a magnetic gear the scale of which is read on an external dial. Visual flow indicators can be built just for one version of the fluid, also free flowing.
Other special features include: executions in different types of material depending on the fluid to control; execution with threaded or flanged connections.