Using a Rotameter as Flow Transmitter

I'm takin a guess, but the float would be a material that will stick to a magnet (iron?) that moves up or down the steel tube and a magnet or magnetic pickup on the outside of the tube can move in unison with the float, but on the outside of the tube. This vertical height is linked to the pointer and other electronics to allow local indication and porbably a 4-20mA output to control room or recorder or PLC or any other indicating device.

ROK

You may have a Linear voltage differential transformer performing the sensing.As the float moves up or down, it couples the primary of a transformer to 2 secondaries.The output of these two secondaries is amplified to provide a position signal, which is converted to milliamp or digital output. IF the switch is simply off-on, then there is probably an external reed switch operated by a magnet on the float, through a non-magnetic tube of some type(SS/Plastic) -----------ShoeShineBoy-----------------------------

Hi there,

Firstly - the principle of measurement is VA (Variable Area). The VA meter is more commonly refered to as the Rotameter.

They are good choices for low-flow measurement because of cost. They are limited to vertical installationsc clean liquids, pressure and temperature ratings.

How do they work?

The flow passes through the VA pushing the metering float up to a position - indicating a ceartain flow. Important - The position of the float in the tube varies in a linear relationship with the flow rate. There is a magnet in the transmitter. As the float position varies - so will the magnet position. Now think for a moment that the magnet is coupled to a direct indicator. As the magnet position changes - so to will the indicator pointer.

The same will happen in the transmitter.

It is important to keep in mind that some VA meters can be installed in the horizontal positions, and in some apllications (liquid metal for example) the flow is from top to bottom instead of bottom to top.

for some good reading - www.khrone.com Go to manuals and VA meters. This will give you some good reading - and they make very good flow meters!

Regards,

Craig

Perhaps a telephone call to Yokogawa's local technical sales agency?

I think so .In rota meter differential is constant.Only area is varibale.so it can be measure flow and float density should be higher than measure flow.