Kurz Instruments Inc. December 13, 2007
360210-AH Rev.A 504/534FTB Installation AH - 8
Water Ingress Protection
The leading cause of a malfunctioning flow transmitter is water penetration in to the
sensor electronics or wiring terminals. The electronics enclosures have a NEMA 4X or
IP66 rating but the transmitters are still subject to water damage if not properly installed
and maintained.
Protective measures for keeping water out of the flow transmitter components.
• Installation of conduit seals (Ex type potting Y work well) near the enclosures on
all ports.
• Most cable gland designs not only provide for shielded cable termination but an
environmental seal against dirt and water.
• Routing of conduit or cable using a water loop and drain near the enclosure ports
• Keep the enclosure lids on tight using the supplied o-rings.
• Positive pressure dry purge air to the enclosure will keep condensation out (few
PSI from a regulator).
Conformal coating of the circuit boards is standard but this only protects against
condensation of trapped water vapor which forms from cooling inside the
enclosures/conduit. Every 10 minutes a sensor and wiring leakage test is performed.
This will set an alarm (Modbus, LCD and NE-43) when excessive leakage is observed.
Flex Wiring Connection for Sensor Inspections
To support periodic and preventative maintenance, the sensor electrical connections
should be done with extra cable or flex conduit length. This allows the sensor to be
removed from the process for inspection and or cleaning without disconnecting the
wiring. The transmitter attached (TA) versions have only power and 4-20 mA wires are
being routed out and use standard electrical wring practice as shown in Figure AH-5.
However, the trouble is maintaining the EMC requirements on the wiring at the same
time. If we are using a transmitter separate (TS) version, the sensor is remote from its
electronics, we must use an approved shielding method. The 5-wire sensor connections
are described in a later section.
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