In certain circumstances, it may not be feasible to install a GW50 or GW50PC nitrate sensor due to a lack of a suitable bore. In such scenarios, the GW50FC nitrate sensor has been devised to offer an alternative solution. The GW50FC sensor consists of a configuration that allows water to be pumped from the groundwater well and directed through pipes to the sensor. This approach enables the sensor to effectively measure nitrate levels even in instances where a standard bore cannot be utilized.
The presence of biofilms on the measurement cell of GW50 sensors due to biological activity in groundwater has been observed. To mitigate this issue, we have investigated the effectiveness of a water jet as a cleaning method. Results from our tests indicate that this technique is an efficient way to decrease the frequency of manual cleaning in most cases. In fact, our trials demonstrate that sensors that would normally require monthly cleaning can go up to 12 months without biofilm build up. It is important to note that although suspended particles of both organic and inorganic nature may enter the measurement cell, the Pump Cleaner should not be used to address elevated turbidity. Overall, this research has yielded promising results as it provides a solution to maintain GW50 sensor accuracy more effectively, while reducing labour and operational costs.
The successful operation of the GW50FC sensor is dependent on the source of water pressure, which must remain below 1 Bar to prevent damage. The water supply must either be gravity-fed or pumped to maintain appropriate pressure levels, and a pressure reduction valve is recommended if the pressure exceeds 1 Bar.Â
The sensor is equipped with a ½ inch BSP push lock fitting and a standard fitted 13mm hose tail, although other hose tail sizes may be obtained if necessary. The flow of water does not matter, but it is advised that the inlet side is positioned lower than the outlet side to prevent any long-term issues with measurement accuracy due to air bubbles. Above ground temperature conditions can fluctuate rapidly, therefore we recommend installing the sensor in a thermal enclosure with additional thermal mass to minimise temperature swings.
 Continuous water flow enables the internal logger to record N03-N readings at predetermined intervals, and an electronic solenoid valve with a suitable control circuit may be installed to activate the sensor. In the case of intermittent water supply, a third-party device configured to communicate with the sensor is advised as the GW50FC cannot detect pump operation.
Maintenance requirements for the GW50FC sensor are minimal. As the sample is flowing, biofilm or other contaminant build up are often reduced. Only occasional manual cleaning is required.
If cleaning is required, the hose attached to the push lock fitting can be removed to allow for a quick brush with Isopropyl Alcohol or 70% Ethanol to clean the measurement cell.
