Contrec 515 series with FA01 application pack is an add or subtract flow computer that is tailored specifically for volume measurement. It can perform either addition or subtraction on two frequency inputs or two analogue inputs.
The flow computer is suitable for accepting signals directly from flowmeters or for collecting retransmitted signals from other flow computers providing a resultant rate and total. The instrument displays the flow rate and total for each channel as well as a result.
The frequency input is compatible with a wide range of frequency signals, including millivolt signals, reed switches, Namur proximity switches and pulse trains via its smart front panel program selection. The analogue input can be scaled and have filtering, non-linear correction and cutoff points applied to the signal.
For frequency inputs, the calculation of totals is exact as the instrument collects all pulses detected on each channel.
Channel total = pulses/k-factor
The flow rates are derived from an accurately measured frequency:
Channel flow = frequency/k-factor
For analogue inputs, to derive the flow rate, the analogue input is normalised to a value (A) between 0 and 1.
Channel flow = (Vfmax – Vfmin) A + Vfmin
Channel total = (channelflow. Δt)
The resultant values are then:
ADD result = channel 1 + channel 2
SUB result = channel 1 – channel 2