How to refill a SR20-AC32 Bellomatic sensor? How to remove the electrode from the top of a Bellowmatic sensor if it is stuck?

First - when you receive a new Bellomatic sensor it is shipped with a rubber stopper inserted into the pressure port on the bottom of the sensor. You must remove this stopper before putting the sensor in service. DO NOT DISCARD THIS STOPPER! Put it in a safe place where you can find it again because you need it to refill the sensor with KCL solution. 

Second - Which KCL solution to use. 

We normally use the standard 3.3 Molar KCL in the Bellowmatic Sensor. We also offer a Thickened 3.3 Molar KCL solution for high temperature applications. This allows the KCL to flow at about the same rate at a high temperature that the normal KCL flows at room temperature. 

Third - How to refill the sensor.

Materials needed: KCL Solution, Rubber Stopper, Long object like a wooden pencil or chopstick, paper towel or tissue to dry the top of the sensor.

1. If the KCL solution is used up the bellows inside the sensor will be fully extended to near the top of the wide part of the sensor. Locate the rubber stopper and insert it into the pressure port at the bottom of the sensor:

2. Unscrew the connector from the top of the sensor and remove the Reference electrode from the top of the Bellowmatic assembly:

Occasionally the bottom part of the electrode will stick to the Bellowmatic Assembly and you will remove only the plastic cap leaving the electrode and the glass surrounding it inserted in the top of the Bellowmatic Assembly:

If this happens you need to carefully remove the electrode from the top of the Bellowmatic Assembly without breaking the glass. 

Wipe with a damp paper towel, then dry off the outside of the glass portion at the top to remove any remaining KCL from the area that makes contact with the neck. Reinsert the electrode into the plastic connector and set it aside until you are ready for reassembly. 

3. Holding the Bellowmatic over a container or sink remove the rubber stopper. If the bellows was not fully extended KCL may squirt out when the stopper is removed. Using the Pencil or Chop Stick press down on the bellows from the top until it is fully compressed, then, holding the bellows in the compressed position, install the rubber stopper sealing the Pressure Passageway at the bottom of the sensor. 

4. Pour out any remaining KCL in the Bellowmatic Assembly, and rinse a couple of times with a small amount of the new KCL solution.  Then fill the chamber just to the bottom of the neck above the bellows chamber. Dry off the top of the sensor where the electrode screws into the Bellowmatic Assembly. Reinstall the electrode slowly, making sure the KCL solution does not overflow out of the top of the sensor. If this area at the top of the sensor is wet with KCL when you reinstall the electrode it is more likely to stick the next time it is disassembled. 

5. Once the top of the assembly is sealed you can remove the rubber stopper, store it back in its safe place, and place the Bellowmatic Assembly back in service. 


Top