With the constant growth of science and technology different types of measuring instruments are invented by human, one of them are flow meters. Flow meters help to measure the flow rate of certain type of liquid and gas. Flow meters are available in different types like oil flow meter or air flow meter , they also vary in the measurement amount that means how much amount passes through a flow meter during a specific time spam. Low flow meters are those which measures very low flow rates of liquid application. Low flow meters are used both for domestic and industrial purposes. Low flow meters as name suggested measure very low amount of water so it is beneficial to know the quantity of the water in homes, industries and at public places which helps in planning to conserve the water for future use. Flow meters are basically of two types depending upon the measuring the flow of the water, these are positive displacement flow meter and the velocity water flow meter. In the first type of flow meter the mechanism which is used to measure the flow is compare with the previous flow of the water. Number of times that chamber is filled is the quantity of water. In second type of flow meters the volume of water is measured by measuring the velocity. The main features of a Low flow meter are:-Ads by Google Low flow meter helps in measuring the very less amount of the liquid which makes it good for home use and small industry use. Low flow meters far less costly as compare to other flow meters Low flow meters are very easy to access, clean, assemble and disassemble in the field, which makes it user friendly. Low flow meters are relatively small in size which helps to reduce the relative velocity. Though these Low flow meters are small in size so it is very easy to maintain them. Low flow meters are very useful in homes, apartments and offices as they are considered to be more accurate, along with that it is very easy to install these low flow meters and having all the attractive features. Low flow water meters are also becoming popular as they helps to prevent unnecessary wastage of water which we can use later on. These Low flow meters are usually able to measure the low flow rates of water which makes it more useful in homes and small industries. Measuring an engine oil flow rate is one of the most difficult flow measures. Low flow meters are helpful in these as well. Automotive engineer uses low flow meter to measure less quantity and that too with a very slow rate of flow under certain operative conditions. So low flow meters are actually very helpful in almost all the industries as well as home uses, which is making it more popular among the people. All in all it will be a wise decision to choose a low flow meter rather than going for some sewage flow meter.

Using the principle of ultrasound, ultrasonic flow meter is used to measure the velocity of a liquid or gas. They don't use moving parts and thus are inexpensive to use and need very less maintenance. They are highly affected by density, velocity and temperature of the flowing medium. There are three kinds of ultrasonic flow meters; transmission, reflection and open channel flow meters. Transmission flow meters can be divided into intrusive and non-intrusive varieties. Flow meters that use Doppler shift are reflection or Doppler flow meters. Ultrasonic flow meter works on the principle that measures the difference of the transit time of ultrasonic pulses that transmit signals through the flow. Also, the difference between the two transmit times is used to calculate the flow rate. They are also more accurate and reliable than any other system. Ultrasonic flow measurement technology consists of transit-time technology, where the two transducers both as an ultrasonic transmitter and receiver; Ultrasonic Doppler technology, in which two ultrasonic transducers are employed in the system and lastly cross- correlation measurement, in which turbulence at a certain distance are correlated. Let us now talk about Hand hold Ultrasonic Flow Meter and ultrasonic portable flow meter in detail.