Water Well Impeller Damage
Water Well Impeller Damage
(OP)
Anyone out there hear of damage to bronze impellers in water wells due to chlorinated pre-lube water? Or leaking check valves allowing chlorinated distribution water to enter the well and corrode the impeller?





RE: Water Well Impeller Damage
RE: Water Well Impeller Damage
RE: Water Well Impeller Damage
Copper alloys corrosion
S.
Metal Corrosion
RE: Water Well Impeller Damage
Chlorine will attack and dissolve the zinc thereby pitting and eroding the bronze impeller.
I've not seen it on raw water well impellers; but, I have seen it numerous times on high service pump impellers and also on solenoid valves for chemical feed piping. The chlorine levels don't have to be that high depending on the TDS content of the water.
I've made recommendations to several clients and changed my specifications to include cast iron impellers where I think this could be a problem. Some manufacturers have different bronze alloys for this reason as well; but, it isn't always easy to find in their literature.
RE: Water Well Impeller Damage
RE: Water Well Impeller Damage
I would suggest getting an analysis of the ground water you are pumping.
RE: Water Well Impeller Damage
There are impellers available for use where the liquid medium has harsh effects on the normal bronze alloys. They are made of a composite fibre material and are resistant to the usual scouring and cavitation. I do not have the info to hand but an internet search should produce a result.
Offshore Engineering&Design
RE: Water Well Impeller Damage
RE: Water Well Impeller Damage
RE: Water Well Impeller Damage
RE: Water Well Impeller Damage
Graphitization is a process where iron leaches from cast iron and weakening the cast iron.
http://www.hghouston.com/coppers/brass75.htm
Bronze is an alloy of copper, tin, zinc, phosphorus, and sometimes small amounts of other elements. Bronzes are harder than brasses. Brass is an alloy having copper (55%–90%) and zinc (10%–45%) as its essential components. The properties of brass vary with the proportion of copper and zinc and with the addition of small amounts of other elements, such as aluminum, lead, tin, or nickel.
In talking to a well driller today, it is more common to experience corrosion of the stainless shaft of the well pump rather than with the bronze impeller. This would be pitting of the stainless steel.
Wells are annually disinfected for a period of 8-24 hours with a solution of 200 to 400 mg/l of chlorine. Again, this is just one time per year disinfection. After 7-8 years of annual disinfections, there will be evidence of corrosion on the pump shaft, not the bronze impeller.
The chlorination of the water supply would consist of approximately 2 mg/l of chlorine and it would be difficult to see how this would affect the bronze when the 200-400 mg/l of chlorine does not corrode the bronze.