How are the housings for refillable pressurized pH / ORP sensors such as the ChemoTrode actually pressurized?
The ChemoTrode requires a pressurized housing such as the MasterFit or RetractoMaster for proper installation. These housings use a Dunlap valve (bicycle tube valve) which permits pressurizing the chamber with the sensor up to 6 Bar. A simple bicycle pump with a Presta or Dunlap pump head can be used for this purpose.