Wet‐pipe fire sprinklers and water quality

Abstract

Class 2 wet-pipe fire sprinkler system s. Th is in vestigation evalu ated th e water qu ality in Class 1 an d Class 2 wet-pipe fire sprin kler system s to determ in e wh eth er firesprin kler system s pose a pu blic h ealth h azard an d evalu ated th e effectiven ess of retrofittin g th ese system s with backflow preven tion assem blies based on cost-ben efit an d risk con sideration s. Previous studies have answered some questionsHave fire sprinklers caused cross-connections? Alth ou gh th ere are n u m erou s, well-docu m en ted in stan ces in wh ich cross-con n ection s h ave con tam in ated drin kin g water an d produ ced illn ess, fire sprin kler system s h ave n ot been clearly im plicated. 1 Docum en ted cross-con n ection effects of fire services date back to 1903, wh en backflow occu rred in Lowell, Mass., du rin g a firefigh tin g operation ; th e crosscon n ection cau sed an ou tbreak of disease an d death s resu lted. 2 Preven tive m easu res developed to safegu ard again st fire crosscon n ection s in clu de th e u se of addition al ch eck valves on fire sprin kler lin es to preven t th e in trodu ction of con tam in an ts in to th e drin kin g water su pply. Of 398 backflow in ciden ts reported sin ce 1900, 4.3 percen t (17) are assu m ed to h ave in volved backflow of wetpipe fire sprin kler system s in to potable water lin es. 3,4 Is water in fire sprinkler systems potable? Man y stu dies of th e qu ality of fire sprin kler water h ave been perform ed by variou s m u n icipal water pu rveyors, bu t few are form ally pu blish ed or docu m en ted. As an example, in 1975 th e City of Portlan d (Ore.) Bu reau of Water Works an alyzed th e water in eigh t sprin kler system s th at h ad been in stalled between 1926 an d 1964. 5 Sam ples were collected from th e in spector's test con n ection . All samples exceeded drin kin g water stan dards for lead (Pb), iron (Fe), an d tu rbidity. Som e of th e sam ples exceeded Charlotte-Mecklenburg

Determining vulnerability and occurrence of residential backflow

“…The use of backflow preventers such as nontestable double check valves on residences may be considered. However, the authors believe these may give utilities a false sense of security, given an annual failure rate of 8.7% (Duranceau et al, 1998). If backflow prevention assemblies cannot be tested, they should be assumed to be nonfunctioning.…”

Corrosion Control Inside Water-filled Steel Fire Sprinkler Piping

“…Freshly expelled ferrous iron ions, iron(II), can transform electrochemically to ferric iron ions, iron(III), via the acid-oxygen corrosion process and also via metabolic activities of iron-oxidizing bacteria that extract an electron from iron(II). Concentrations of dissolved iron ranging from 10 to 494 mg/L have been measured in pipe water drained from operating steel fire sprinkler piping systems [15]. Comparing these concentrations with the dissolved iron concentration of 0.3 mg/L or less in water charged into fire sprinkler piping from public water supplies [16] shows that corrosion can increase dissolved iron concentrations in closed steel piping systems by about 10-1000 times.…”

Development of performance indicators for small Quebec drinking water utilities

“…Periodical flushing may be an efficient way to ensure overall distribution system healthiness, since it makes it possible to remove biofilm and corrosion tubercles, both favoring drinking water microbiological quality deterioration within distribution lines (Antoun et al, 1999;Duranceau et al, 1999). Therefore, the distribution system flushing variable was retained for the utility performance indicator development.…”