DFMEA

ITEM AND FUNCTION	POTENTIAL FAILURE MODE(S) Consequences (What would happen if we didn’t have this!!)	POTENTIALCAUSE(S) OF FAILURE	SEV	POTENTIAL EFFECT(S) OF FAILURE	OCCUR	CURRENT DESIGN CONTROLS	DETECT	RPN	RECOMMENDED ACTIONS
1. SSF
a. Sand
i. Washing	Tubid water	improper washing	6	High turbidity	5	Netting	2	60	wash thoroughly
ii. Grain Size	Turbid water,flowrate, and filtration quality	improper sieving or selection	6	Contamination	5	Proper Selection	4	120	follow instructions
iii. Depth	Turbid water, flowrate, and filtration quality	settling, improper measurement	8	Contamination	3	Weight to Volume Ratio	4	96	Induce settling, add sand
iv.  Life	Doesn't meet specifications	Prolonged use	8	Reduced Flowrate	2	NONE	9	144	Replacement
b. Gravel
i.Grain Size	Sand movement	improper sieving or selection	6	Flowrate	3	Proper Selection	4	72	selection, visual inspection
ii. Washing	Turbid water	improper washing	6	High turbidity	5	Netting	2	60	wash thoroughly
c. Barrel
i.  Wall	Barrel wall integrity	cracks, UV deteriation	8	Blowout	2	Visual Inspection	3	48	selection and barrel placement
ii. Lid	Further contamination	not using	5	further contamination	2	Visual Inspection	3	30	Fits Barrel
d. Piping
i. Clogging	Flowrate, turbidity	Sand movement	8	Reduced Flowrate, high turbidity	4	NONE	8	256	Method for checking for clogged pipe
ii. Connections	Contamination of clean water	Improper seals	8	contamination	4	Visual Inspection (leaks)	4	128	Check seal
f. Valve
i.  Clogging	Flowrate	Sand movement	8	Flowrate	4	NONE	8	256	Method for checking for clogged valve
ii. Jamming	Flowrate, Usability	Gravel movement	6	Not usable	4	NONE	8	192	Method for checking for jamming in valve
iii.  Breaking	Usability	Natural disturbance	7	Not usable	4	Visual Inspection	3	84	Visual Inspection
g. Schmutzdeke
i.  Life	Incomplete Filtration	Lack of oxygen/nutrients	9	Death of Schumtzdeke = contamination	6	Visual Inspection	6	324	Visual Inspection Method of growth
ii. Layer Thickness	Flow rate	Maintenance	9	Reduced Flowrate	6	Visual Inspection	6	324	Measurement Device
k. Diffuser Plate
i.  Clogging	Usability	Large particles	8	Increased pouring time	4	Visual Inspection	2	64	Method for checking for clean plate
ii.  Size	Poor water quality	Improper sizing	8	destroy schutzdeke	4	Selection	2	64	selection