SA flow sensor
Setup and support
Installation guidelines

Installation guidelines for the SA flow sensor

For best performance of the SA family of sensors, please adhere to the following guidelines.

Insertion depth

As seen in the Technology section, the SA sensor monitors the difference in temperature of two RTDs - one located at the tip that reacts as the flowing medium conducts heat away and one located ~15 mm above that provides the medium reference temperature.

The position of the RTD and heater at the bottom of the sensing tip.

To accurately account for any medium temperature changes, the tip of the sensor must be located within the flowing medium. The SA4 series offer sensors with 100 mm or 200 mm probe lengths used with compression fittings for adequate insertion depth in larger pipe sizes.

SA flow sensor mounted in a pipe with proper insertion depth and chart of insertion depth vs. pipe diameter — Minimum insertion depth based on pipe diameter

Note: For very viscous or high-velocity media that exerts a strong bending force on the probe, the above insertion depth should not be exceeded.

Pipe mounting

To help ensure the sensor tip is surrounded by the medium, always mount the sensor in a vertical section of pipe with flow going up. This method guarantees the pipe is full. If horizontal mounting is the only option, mount at an angle in case the pipe may not be full.

SA flow sensor mounting recommendation — Recommended mounting

If the pipe is guaranteed to be full, the sensor may be mounted from the top.

Because of the principle of operation, build-up on the sensor tip affects heat conduction. If the medium is free from build-up, horiztonal mounting from the bottom is possible.

Be sure to thoroughly test the sensor in these situations.

Conditional mounting positions for SA flow sensor in a pipe — Conditional mounting

Two mounting situations that are not recommended in any case are:

Sensor tip in contact with the opposite pipe wall. This will adversely affect the heat conduction process.
In a pipe with downward flow that is open to atmosphere and not a closed loop system. The velocity profile in such a situation is not repeatable.

Mounting positions not recommended for the SA flow sensor — Not recommended

Straight pipe run

The SA sensor is the most reliable and repeatable when the sensor is installed in laminar flow. Valves, bends, flow constrictions, etc. all cause turbulence.

To avoid influences of turbulence, maintain a straight run of 5...10 x pipe diameter upstream of the sensor and 3...5 x pipe diameter after the sensor.

SA flow sensor installed in pipe with proper upstream and downstream straight runs — D = pipe diameter, S = source of turbulence

Alignment

The SA sensors either have a dimple on the mounting nut (on units with threads) or a large and small wrench flat (for units requiring compression fittings). The dimple and large flat indicate the side of the probe where the reference RTD is located. For best response to change in medium temperature, install the sensor with the flow hitting this reference side first.

If necessary to read the display, the sensor housing can be rotated up to 345°.

SA flow sensor installed in a pipe with callouts for reference locations — 1 = wrench flats, 2 = dimple