Condensation collecting inside pressure sensors is a common problem, particularly hydrostatic and process pressure transmitters in the food, beverage, pharmaceutical sectors and applications outdoors . It occurs in any environment where a warm process meets cold air, or vice-versa. Water will condense out of the air onto any surface, no matter how small. If you add temperature cycles, high humidity, regular wash downs and pressure cleaning, it is often only a matter of time before issues occur.
Problemet er, when air needs to breathe into the device to reference the measurement against atmospheric or gauge pressure, it needs to do this right down inside the measuring cell itself. But air will also carry miniscule amounts of water, ready to condense out under the right conditions even in these tiny areas where the measurements are being made. A microscopic amount is all it takes to create error and drift in sensitive electronic systems designed to detect a diaphragm deflection of only a few microns. Many designs resist condensation, but no matter how carefully it is constructed, condensation will eventually find its way inside the sensitive electronics. It may take weeks or years, starting with drifting, needing recalibration more often, then eventually failing altogether.
To overcome this, VEGA has designed a special VEGABAR pressure transmitter, which uses two high accuracy sealed ‘absolute’ measuring cells. One cell measures barometric or gauge pressure, the other for the process pressure (including gauge) they are mounted in an IP66/IP68 housing with a Gortex breather. The design completely isolates the sensitive measuring cell circuits and all other electronics are fully potted. This means that when any condensation forms, it remains in the wetted ‘process side’ of the device, not in the electronics.
VEGABAR has options for ceramic and metallic diaphragms with flush process connections from only ½” with welded and replaceable elastomer sealing arrangements. Also there are relevant approvals including FDA, EHEDG and 3A, a selection of flush, hygienic fittings and suspended versions for top mounting . These devices are part of the VEGA plics range, offering a host of useful features, such as integrated data logging, 4 communication options and back lit display, a modular build and a variety of designs on SPEED delivery.
VEGA Controls Ltd
VEGA fremstilling niveaumåling, niveaukontakt, interface, tæthed og proces pres instrumentering.