Tecfluid SC250H - Manual (Page 3)

3
1 WORKING PRINCIPLE
The series SC250H & SC250V of variable area flowmeters
consists of a metering tube, a calibrated orifice inside it, a
conical float and a compression spring whose force is
opposed to that performed by the fluid. The fluid flow lifts the
float to an equilibrium point. The area obtained between the
float and the orifice is proportional to the flow rate.
This type of measuring principle is known as variable area.
The equilibrium point depends on :
 The float force:: Ff
 The fluid thrust : E
 The free flow area : Al
The area proportional to the flow rate will be:
Al = Ao - Af
where:
Ao = Area of calibrated orifice
Af = Float area
2 RECEPTION
The flowmeters series SC250H & SC250V are supplied tested in our calibration rigs, ready
for installation and service.
The instruments are supplied packed for their protection during transportation and storage.
Likewise they have blocking elements that should be removed before installation.
Check that the float moves freely and that the indicator needle, starting from zero, follows
the float movements over the whole scale and returns to zero.
3 INSTALLATION
The flowmeter SC250V must be installed in vertical position (upwards or downwards flow
direction). The flowmeter SC250H must be installed in horizontal position (left or right flow
direction).
The flowmeter must be installed so that the flow direction indicated on the plate of the
instrument matches the flow direction of the fluid.
The “0” of the scale indicates the entrance of the fluid into the meter, and the end of the
scale indicates the flowmeter outlet of the fluid.
It is important that the position is completely horizontal or vertical (depending on the model
of the instrument), given that deviations of about 5º can produce errors of about 8-10% of
the readings.