How often do you calibrate your level transmitters?

Level Measuring Transmitter is a gadget giving consistent dimension estimation. An extremely normal and down to earth utilization of the transmitter is to gauge anything in bulk– fluid or solid– utilized for procedure control. Diverse dimension transmitters have distinctive working rule. In this article, we are going to connect with a couple of their sorts and investigate the point by point purpose for adjusting them.

Types of Level Transmitters

Utilizing in a bunch of uses that requires estimations of levels inside holders or tanks, Level Measurement Transmitter dependably comes helpful. These transmitters are pertinent in numerous businesses, for example, water treatment ventures, control synthetic compounds, sustenance and drink, and material dealing with. It tends to be helpful in different distinctive kinds of procedures.

Capacitance Level Transmitters– Transmitters with a dielectric medium between at least two terminals put away in a tank or holder. Capacitance level transmitters can compute the current-fill dimension of the tank or compartment.

Hydrostatic Level Transmitter– Transmitters that decide liquid substance of a compartment by estimating the nearness of a resting body of the liquid inside it. Additionally, known as weight level transmitters.

Attractive Level Transmitters– Transmitters that are suspended in a light buoy, as a rule in a thin assistant section. These utilization attractive items as transmitters and help in estimation inferable from the inclination to buoy or sink on the fluid dimension.

Ultrasonic Level Transmitters– Transmitters with ultrasonic transducers mounted at the best or close to the highest point of a compartment. They empower the transducer to send a ultrasonic heartbeat and get reflected after getting hit. The sensor computes the dimension dependent on the time among transmitted and got the reflected flag.

WHY CALIBRATE?

1.    Comply with regulations

2.    Maximize process performance

3.    Maintain safety

4.    Quality Control:

How does Radar Level Transmitter work?

RADAR (Radio Detection And Ranging) is a device which can detect the presence of faraway objects by obtaining a reflection of electromagnetic waves emitted from the device itself. Although invented much earlier, wide deployment of radar was done by Britain during the Second World War to detect oncoming German bombers. Initially, radar was deployed for military purpose and for weather forecasting. Recently radar principle is used for industrial applications also.

Measurement of the level of liquids and solids is one such application

Radar level transmitters make use of radio or electromagnetic waves of very high frequency in Gigahertz (GHz) range. There are two types of radar level transmitter  1) Guided wave radar transmitter, 2) Non-contact type radar transmitter.

1. Guided wave radar transmitter –It is based on ‘time of flight’ principle. It consists of electronics housed in an enclosure and a waveguide i.e. probe to guide the radio wave into the process media.  Low energy electromagnetic pulses of 1 GHz from the electronics are transmitted along the probe which travels down along the probe at the speed of light into the process media and their partial energy is reflected back to the sensor circuitry. The intensity of reflection depends on the dielectric constant value of media. The electronics measures the time delay between transmitted and reflected signal and calculate the distance of the surface of process media using formula –

Distance = (Speed of light x time delay) / 2, Level = (Tank height – Distance)

The transmitter is programmed with tank height and the corresponding level is calculated by microprocessor.

It is also used for liquid-liquid interface level measurement only when upper layer media is of low dielectric and difference between two dielectric constants is >10. Residual electromagnetic pulses after the first relection continue to travel down the probe through the low dielectric media and again reflected back. Second reflected signal determines the interface level.

Advantages –

Provides accurate & reliable level measurement of liquids, slurries, pastes , liquid interface & solids.

Suitable for low dielectric constant media.

Unaffected by liquid turbulence, change in density, dielectric constant, conductivity, foam, dust, temperature & pressure

Minimal maintenance as no moving parts

2. Non-contact radartransmitter  - It uses high-frequency microwave signal of 26 GHz which is transmitted via an antenna towards the product surface. Its frequency increases linearly during the measurement. The signal is reflected back to the antenna from the surface of process media and received at the time-delayed frequency. The difference is calculated from actual transmitting frequency and received frequency which is directly proportional to distance to the liquid surface from antenna.

The frequency of non- contact radar affects on the performance of the transmitter. Lower frequency increases the beam width and reduces the sensitivity due to vapor, foam, and deposition on the antenna. With higher frequency, the beam width is narrowed which minimizes the influence of nozzle, wall and tank internals.

Advantages –

Suitable for liquids, solids & granules

Reliable performance with high accuracy up to 1mm

Choice of antennas- sealed rod, horn, drop or parabolic to suit the application

Unaffected by liquid turbulence, change in density, dielectric constant, conductivity, foam, dust, temperature & pressure

How to measure water level in closed tank

Measurement of level of water in the Boiler drum is a classic example of water level measurement in a closed tank. In this case, as water in the drum gets heated, it turns into steam and builds up pressure above the water which is more than atmospheric pressure.

Closed water tanks are also made use of in high-rise buildings for domestic water supply. By providing pressurized underground water tank, the need for deep and extra strong foundation for the building can be avoided, which otherwise would have been needed in case of an overhead water storage tank. The underground tank is kept under pressure by compressed air. As compared to the “open to atmosphere” tank, in a closed tank, the pressure above water may change due to consumption of water from the tank or by addition of water into the tank.

Measurement/detection of water Level in closed tank can be done by various methods and by making use of various types of instruments.  PTPL manufactures a large variety of instruments required for this purpose.

A] Direct reading level gauges:-  Tubular  Level Gauge - TTG, Reflex Glass Level Gauge- RFG, Transparent   Glass Level Gauge – TFG, Magnetic Level gauge- MLG, These gauges are also available as IBR approved gauges for boiler drum level applications.

B] Level switches:- Float Pivoted Switch- FPS, Float Guided Switch –FGS, Displacer Switch-DS, Capacitance Switch – CPS, Conductivity Switch – CNS, Chamber Float Switch- CFS, Mobrey Type Vertical Level Control- VLC. Suitable switch can be selected from this range depending upon temperature & pressure rating