What is the temperature range for the HI 2151/30WC?

Radiant heat from the sun seems to be causing the output of our HI 2151/30WC to fluctuate. This problem can be seen on our calculated flow. The flow is calculated using old data, fifteen minutes prior, minus current data multiplied by four to bring it to an hourly rate, then multiplied by one thousand to display in klbs/hr. The fluctuation is not as readily seen on the 4-20mA signal, but is definitely noticeable on the calculated flow. Does the HI 2151/30WC controllers have any history of heating problems in the electronics?

We might install a heat shield to shade the instrument with a two inch air gap and increase the air flow if this will help?

The operating temperature range for the HI 2151/30WC is from 14 to 122 degrees F (-10 to +50 C). Anything outside of this range can cause abnormal behavior. Installing a heat shield to keep the temperature within the spec's is recommended. Installing a fan to increase air flow may be an alternative solution, depending on your site specific situation.

A temperature change can affect weight readings. This will not normally cause a fluctuation in the readings. As the temperature changes, the outputs of some of the components can change, but this would be a change based on the temperature. If the temperature is constant, then the output would be constant, although possibly incorrect. To get a fluctuation caused by temperature, you would need to have the temperature constantly changing up and down.

If a system is running well at a cooler temperature and then runs erratic at a higher temperature, it could indicate a problem with the installation. With fluctuations like you are describing, this could be caused from binding, as anything attached to the load cell system can expand/contract with temperature changes. Another possible cause could be if the vessel is mounted with rubber bushings between the load and the load cells, is that as the bushings get warm, they become more flexible allowing the vessel to "sway" back and forth. This can then show up as fluctuation of the readings.