M&C TechGroup FA-1_2_3,bi Operator's manual - Manual (Page 9)

9
Gas sampling and conditioning technology 5-6.10-ME
9 DESCRIPTION
The M&C flow alarm sensor FA-1/2/3bi consists of a compact aluminium body with a fixed, open
prism and a pressure screw. This makes the positioning of the flow alarm sensors FA-1/2/3bi onto the
measuring glass of the flow meter very easy; it is not necessary to disassemble the measuring glass.
Three basic versions FA-1bi, FA-2bi and FA-3bi cover a measuring glass diameter range of 5-55 mm.
Inside the sensor’s body, a mechanically protected, high-intensity LED is mounted on the left side as
light source and two phototransistors are mounted on the opposite side as receivers. The standard
connection cable of 3 meters comes out on the left side laterally to the pressure screw. The light beam
of the LED meets the photo transistors through the flow measuring glass. As soon as the floating
particles interrupt the light beam, one or both phototransistors are blacked out.
The M&C electronic controllers series FA
® are available in 2 housing types for wall mounting or rail
mounting. Both types contain three service functions to be determined via the electrical connection:

Electronic controller for flow monitoring in bi-stable execution in combination with the flow
alarm sensors (forked light barriers) FA-1/2/3bi.

Electronic controller for flow monitoring in mono-stable execution in combination with the flow
alarm sensors FA-1/2/3bi or FA2-H.

Electronic controller for liquid sensor KS 2 or operation in combination with the external pre-
amplifier K-FA, in case the cable length between flow alarm sensor FA-1/2/3bi and electronic
FA-1.. is more than 10 meters or in case of strong straying signals influencing the evaluation
via the sensor cable.
For sure operation, a line break monitoring is integrated. For sure alarm signalling a potential-free
change-
over contact with „Safety-first“ switching is existing. In order to avoid unwanted alarm signals
in case of pulsating gas flow, the alarm switch has got a pull-in and drop-off time-
lag. Two LED’s are
signalling operational or fault status.
The electronic controllers FA-1.. are balanced in the factory relating to the flow alarm sensors FA-
1/2/3bi and the measuring glasses of the flow meter FM-40 7-70NL/h. Additionally, the luminosity of
the flow monitoring sensor FA-1/2/3bi is automatically controlled in dependence on the ambient and
operating conditions (lighting conditions, temperature, agjng of the LED’s, contamination of the flow
meter glass, etc.).
In case of operating a bi-stable flow monitoring, the identification of the set flow value adjusted by the
flow alarm sensors FA-1/2/3bi is guaranteed in case of exceeding or falling below the present value
(MIN or MAX). In case of mono-stable operation, there is only an indication given whether the floating
particle is located in the light beam of the flow alarm sensor FA-1/2/3bi or above or below it
(see figure 1).