Diesel Flow Meters

Many different techniques are used to sense the oscillation or rotation of the displacement mechanism and its elements. The purpose of the counting system is to transmit a measurement of the fluid flow in terms of total volume, or flow rate expressed in volume per unit time. Examples of totalized volume include gallons (gal), litters (lit), barrels (bbls), and cubic centimeters (cc). Examples of flow rate include gallons per minute (gpm), litters per minute (Ipm), barrels per day (bbls/ day), and cubic centimeters per second (cc/sec).

In traditional positive displacement flowmeters, the primary counting system utilizes a mechanical counter drive train directly coupled to the displacement mechanism. The counter drive train is used to transmit the internal motion of the displacement mechanism into a usable output signal. Some positive displacement flowmeters use a mechanical gear train that requires a rotary shaft seal or packing gland where the shaft penetrates the external housing. The counter drive train can be used to operate a locally mounted mechanical register or totalizer. This type of purely mechanical system is inherently intrinsically safe since there are no electrical signals. However, a potential disadvantage is the inability to retransmit the flow signal to remote instrumentation.

 

Many mechanical counting systems for positive displacement flowmeters have been upgraded to include electro-mechanical pulse generators to provide the remote signal transmission capability. These pulse generators allow electronic rate indicators, totalizers, and/or transmitters to replace traditional mechanical registers/counters.