© 2021 VPInstruments | MAN-VP-VP38-EN | Revision: 2100 | Date: 25-01-2021
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5
Measurement
For all parameters the update interval is 1 second. Within this second, multiple samples are taken
and averaged to provide a stable and reliable output.
5.1
Flow
The VPFlowScope In-line 3/8" flow meter uses our proprietary insertion type thermal mass flow
sensor. There is no bypass flow, which results in a high robustness and less sensitivity for dirt or
particles. The flow sensor is directly temperature compensated. The flow reading is under normalized
conditions.
The sensor response signal is directly related to
the mass flow rate and can be described by the
following formula:
Vout = k *λ* ρ * v * (Ts-Tg)
Vout = output voltage
k = sensor (geometrical) constant
λ = thermal conductivity of the gas
ρ = density of the gas
v = actual velocity in m / sec
Ts = sensor temperature
Tg = gas temperature
5.2
Totalizer
The totalizer keeps track of the total consumed amount of compressed air in normal cubic meters,
normal liters, normal centiliters or in (M)(M)SCF depending on which unit you choose to read out.
The refresh interval is 1 second. Actual totalizer data will be available on the display and via the
Modbus interface. The totalizer value is written to its internal memory with an interval of 15 minutes.
A power failure may result in maximum 15 minutes of totalizer data loss.
The totalizer can only be reset to zero. It's not possible to set it to any arbitrary value.
