Safety notice on digital dosing pumps
Important safety notice for dosing pump systems: Regular inspection of the complete system and proper maintenance of all components is mandatory
Dear Grundfos customer,
This safety warning informs you about the risk of chemical leakage in a dosing system. Please share this notice with your customers (if you have resold Grundfos dosing products) and ensure these points and guidelines are followed.
The notice has become necessary after several site visits where pipework arrangement was of a poor design (e.g. too long and/or too narrow piping, material incompatibility, temperature issues) leaving the potential for chemicals to start leaking. Leaking chemicals on the dosing pump head and/or pipework could be a sign of acceleration head pressure and overtime the chemical could be forced behind the diaphragm, penetrating the assembly between the dosing head and the pump housing and potentially entering the gearbox.
This must be avoided as there is a possibility of an undesired and potentially hazardous chemical reaction inside the motor housing. In this event the pump will be damaged, and the dosing system could possibly become dangerous at worst case leading to an explosion (as already stated in the Installation and Operation instructions). The level and type of hazard is very much dependent on certain criteria being met and which chemical is being dosed.
Regular inspection and maintenance.
We would like to stress the importance of regular maintenance and inspection of your dosing pumps in accordance with the Installation and Operating Instructions, replacing the recommended spares and checking the diaphragm for wear to avoid chemicals getting behind the diaphragm. Visual inspection of the drain of the dosing head, needs to be checked and cleaned if necessary (especially when dosing crystallising media).
These procedures are clearly described in our Installation and Operating Instructions which may be downloaded from Grundfos Product Center.
Detect leakages at an early stage.
To help detect leakage at an early stage, the SMART Digital dosing pump range is available in the FCM (Flow Control Monitor) variant which will detect changes in head pressure. Moreover, for DDA-AR 60, 120 and 200 l/h variants, the option for a diaphragm leakage sensor is available: alarms on the pump will be triggered in case of leakage, warning the operator.
For the DME 3 and 4 ranges (DME 60, 150, 375 and 940 sizes), a leakage sensor safety accessory (PN 96534443) is available that can be fitted in the drain of the DME 3 and 4 -AR and -AP versions and can be retrofitted on existing pumps. This sensor will assist in detecting leakage at an early stage. It will stop the pump if liquid is detected behind the diaphragm and generate an alarm to warn the operator.
The DME 3 and 4 -B variant does not support the leakage sensor. Please refer to the Installation and Operation Instructions for the correct use of these pumps and applicable media.
Grundfos advises and recommends all users of dosing pumps to:
- Make sure, by way of regular inspections, that the pipework installation and the dosing pump is clean and there are no leaks. The source and cause of the leaks must be found and corrected.
- Make sure the dosing pump is serviced in accordance with the Installation and Operating Instructions, especially when it comes to regular replacement of the diaphragm.
- Regularly inspect the pump, and immediately disconnect the pump from power supply if a leakage from the back of the dosing pump head or from the drain is detected. Do not operate the pump again until the cause is determined and corrected. Request Grundfos Service Support if necessary.
- As an added safety precaution Grundfos offers the option of the leakage sensor, PN 96534443, for the DME 3 and 4 -AR and -AP variants (DME 60, 150, 375 and 940 sizes). In case the analogue input is already used, an M12 T-splitter is needed to fit both the sensor and the existing input. Please contact your local Grundfos sales company.
To further help you in preventing leakages in your systems, Grundfos will issue guidelines on best practice for dosing pump installations in pipework systems.
If you have any questions regarding this communication, please contact your local sales company.