Flow and losses through the instrument do seem to be significant: logged pressures jumped from 134m to up to 139m on detaching the device. I want to know whether there's a way of back-calculating the pressure in the main whilst the instrument and pressure logger attached to the same fitting.
Setup: I have a 350mm main to which a y-shaped fitting of small diam piping is attached via a hydrant. A pressure logger is attached to one fork of the fitting and a water quality instrument containing ~2m of ~10mm ID hosing and a flow cell is attached to the other. Water discharges to waste...
